# Slant-Bed CNC Lathe Build



## barnbwt

I have no idea if this is the right place for the build thread, but my home is above my shop, and this CNC project will be in it 

I'll say up front this is a big, big project.  Especially for something that's only the size of an oven.  This first post will be a sort of rolling summary (so long as I remain able to edit it) of milestones passed & yet to be completed.  I will try to mention all the questions I've had to find answers to in order to progress, so that someone embarking on a similar adventure might take a short cut.  If it looks like I'm missing anything, or especially if anything needs clarification or is outright wrong, by all means speak up!  My starting point is as a total ignoramus who only has a couple years' experience with a small manual lathe, and a degree in aerospace engineering.  Having seen what a *well made* machine can do --even a small one-- and the near-limitless capabilities of even simple automation compared to my own abilities, I think it's worth reaching for the stars a bit.

I will have a lot of questions I'll ask here, every step of the way to be sure .  I'm not posting on CNCZone since that place is lousy with abandoned machine-build threads, and it's depressing.  It seems like plenty of ambitious projects happen here, and will way less pretense.  Thanks in advance for tagging along, and of course for any help or advice.

So away we go...

*Overall Concept:*
-Benchtop size, trying to keep it inside a 3ft cube
-Workpiece size 2" x 7.5" (with boring capacity to that depth)
-CNC lathe profiling capability, including threading/rigid tapping
-Light milling capability with a live tool (engraving, slots, helices --real word)
-4000rpm spindle (well over 1000sfm for a 1.25" 'average size' profile)
-Capable of good results on all commonly machined metals (steels, aluminum, brasses, Delrin)
-5C Collet/Closer spindle, with D1-4 mount for chucks
-Design for future; tool changer, tailstock, flood coolant, full closed loop axes, chip auger




That last one (growth capability) is why the machine isn't about 1/3 shorter.

*Design Constraints: All Good Designs Have Restrictions*
-Residential 110VDC/60Hz 1-PH @ 15A, grounded GFCI outlet
-3ft cube external envelope (again)
-500lb weight limit (this is flexible within reason)
-"Easily" moved; it won't be on casters, but I plan for it to have lifting points for a hoist
-Bench top; heavy wooden workbench, but no 'proper' machine platform to stiffen it (also flexible)

*Design Criteria: Brass Tacks by Category*
Complete Parts List (with Purchase Price):
-Used Baldor BSM80C-375AF servo motor (135$ with extra 10:1 gearing) & pulley
-Used Baldor FMH2A09TR-EN43 (267$) & cables
-Nema 23, bipolar, 381 oz-in, 3.5A steppers (tentative) & mount @40$/ea
-Galil DMC-2813 motion controller, 8 axis, ethernet interface (350$)
--Galil SDM-20640 daughter board stepper drivers, 4 axis, 3A & 50V (300$)
-Used Cherokee International QT6A1D 24VDC @ 5A, 5VDC @ 20A Power Supply (24.99$)
-48VDC @ 8A stepper driver power supply (tentative)
-12/24VDC ducted cooling fans (tentative, for servo driver & power supplies)
-16mm OD, 4mm pitch SFU1604 ballscrew & nut, 300mm X axis (30.58$)
-16mm OD, 5mm pitch SFU1605 ballscrew & nut, 500mm Z axis (76.89$)
--BK/BF12 ballscrew bearing mounts qty(2) (0$ part of Z axis order)
--Stainless steel spring coupler 1/4"-10mm, qty(2) (0$ part of Z axis order)
-28mm steel ballnut mounts for 1604/1605 ballnuts qty(2) (20.52$)
-25mm x 400mm linear guideways qty(2) & HSR20CA carraiges qty(4) , X axis (238$)
--25mm x 600mm linear guideways qty(2) & HSR20CA carraiges qty(4) , X axis (0$ part of X axis order)

-1.5" box tubing, 1/4" and 3/16" thicknesses (tentative)
-3/8" or 1/2" steel plate (tentative)
-1" steel plate for carriage & slide table surfaces (tentative)
-1" square cold roll steel bar for spacers (tentative)
-2" square aluminum bar for stepper motor mounts (tentative)
-Spindle assembly (ball bearings, spindle shaft, spindle casing, pulley)
-45x85x19mm Barden 7209/209HCDUL paired P4/ABEC7 angular contact bearings (130$)
-45x85x19mm Fafnir 6209/MM209K P4/ABEC7 deep groove bearing (80$)

Machining Envelope:
-Intended part size is 2"OD x 7.5" stickout (min cutter travel 1")
-Spindle bore pass through 1.25" diameter
-No tail stock at this time, but room to add
-Ability to move to tool changer docking position along X-axis; total travel must be 6"
-Boring depth capacity of 7.5", means Z-travel of carriage must be 15" total
Machining Capability (Forces/Power):
-Capable of machining steels, aluminums, plastics, brasses, and irons
-Carbide cutter speeds (>1000sfm, for a ~1.25" OD part is 3000rpm, so spindle = 4000rpm)
-Shallower/faster cuts acceptable so long as surface finish is not compromised (if possible)
Optimizing Rigidity:
-Beefy, welded truss frame, with several hundred pounds minimum weight
-Optional attachment of mass/dampening material later (iron plate or epoxy granite)
-Heavy gauge plate steel motor & spindle mounting plates at headstock
-Thinner gauge sheet closeout bolted to exterior
-Direct-driven stepper motors
-25mm timing belt drives spindle
-16mm ballscrews, 25mm linear guideways both have far higher load capacity than needed
Optimizing Accuracy:
-Use of linear guideways to constrain axis motion with very little off-axis backlash
-Use of ballscrew drive for axes to reduce backlash (also friction)
-Use of servo motor on spindle to precisely track its position & speed for threading & milling
--May ultimately add a secondary encoder to the spindle to even more precisely monitor position
-May eventually add a second ball nut to either/both axis if the lost cut envelope is acceptable
-Addition of friction brake to spindle to hold it steady during stopped moves (slotting/side drilling)
Minimizing Size:
-Work envelope and machine travel kept to minimum practical size
-Simple single-belt spindle drivetrain
-Z-axis carriage and X-axis cross slide made from 1" steel plate with inset mounting surfaces
-45deg bed slope is the best compromise between height & depth, and a short load path down

Electrical Components:
-Baldor BSM80C-375AF Servo motor is ~1kW, with max RPM of 4000rpm, 2500 pulse/rev encoder, generating 3.6N-m continuous force, and operating at rated 6.29A & 300VAC.  The power figures triple at maximum, but for a lathe such violent power moves are generally unnecessary and indicate more serious problems (crash).  That, and the 1kW resultant power draw make me confident this motor won't blow my breaker in operation (inrush, perhaps).  The way these AC servos operate, is a fancy VFD called a servo driver feeds them a continuous current across the whole speed range, but increases voltage to drive it harder, while increasing frequency to keep time with its spinning (greatly simplified).  This constant torque quality manifests as a nearly flat torque curve across the operating range of speeds.  While the motor is not hugely different from any other induction unit apart from its low inertia, the real magic of servos stems from their precise control; an encoder tracks the exact angular position & feeds that data to the servo driver in real time, where high performance control systems adjust power delivery to quickly react to applied loads on the motor or commands from the controller.
-Servo driver is a 9A unit set up for analog command signals, but digital on the inside so it is also capable of accepting step/direction inputs just like a stepper motor (which are then parsed by a computer & sent to the motor, then adjusted as the encoder reports the response).  The driver actually replicates & outputs the encoder signal, so it can be sent back to the motion controller itself for a complete closed-loop of feedback for all components.  The controlling input pulse is a low level signal, and the computer must be isolated from the enormous & variable motor current, so a separate 24VDC supply is necessary
Component Block Diagram:
http://hobby-machinist.com/attachments/block-diagram-png.239021/
Controls Block Diagram:
-Laptop running Mach3 CAM software -> ethernet -> motion controller
-Motion controller -> servo & stepper drivers -> servo & steppers
-24VDC power supply->motion controller, servo drive
-48VDC power supply->stepper drive
Power Consumption:
-15A 120VAC available, 16A total peak demand (dang, no tunes!)
-9A continuous draw by servo motor drive (at max power)
-2A/120VAC continuous draw by 5A-24VDC/10A-5VDC power supply
--motion controller requires 1A 5VDC
--stepper driver fans require .5A 5VDC
--servo driver requires 1A 24VDC
--servo controller cooling fan requires .25A 24VDC
-5A/120VAC max draw, I think, from 8A 48VDC power supply
--3.5A steppers (3.5*2*.67) comes to 4.7A 48VDC
Mechanical Components:
-25mm linear rails; these carriages are large enough to have zerk lube fittings, and also have external flanges that broaden their mounting footprint.  They also seem to be made to a slightly higher standard than budget smaller rail sizes.
-16mm ballscrew; the 5mm pitch is plenty for my needs and the screw itself is far, far, far, far stronger than any load I'll be applying to it via the stepper motors or cutter.  I wanted more control & resolution in the radial/X direction so I found a rolled 4mm screw.  The balls are smaller so the load capacity is lower, but the greater number of points of contact is ultimately more rigid.
-Ballnut mounts are an off the shelf steel variety paired with my ballnuts
-Stepper motors will be mounted directly to the ballscrews on machined standoffs, the shafts connected by helical couplers
Spindle Construction:
-The spindle assy is a 'cartridge' type that is mounted into the frame in alignment with the axis rails
-The casing will be a simple hollow cylinder bored for the bearing races, with a large square mounting flange welded at each end that will bolt to the frame for mounting
-The spindle will be a 5C collet bore with space for a tubular closer, and D1-4 faceplate for chucks
-Two opposed & preloaded roller or angular contact bearings support the business end, one set of deep groove bearings support the side load of the pulley on the tail end.  All are P4/ABEC7 super precision grade, and 45IDx85ODx19mmW
-All bearings will be labyrinth sealed against debris and will have lube points nearby in the casing
Tooling:
-At least initially, there will be an AXA quick change post mounted on the slide that holds the cutters
-I plan to add a quick-change capability to the surface of the slide itself, of a wedge type similar to the Aloris system, that will be operate as part of the automatic tool change system

Frame Construction:
Maintaining Alignment:
Mechanical Assembly:
Electrical Assembly:
Function Testing & Adjustment:


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## Boswell

Barnbwt,   This looks like it is going to be an interesting build. Looking forward to following your build.
what makes a Slant Bed lathe special? In other words, what can you do on a Slant bed lathe that you can't do on a flat bet?  Just curious


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## barnbwt

The slant bed is cool for a number of reasons, but only one really has to do with the slant itself; the spindle rotates 'backerds' what we manual guys are used to, so the chips fall down off the upside-down cutter on the back side of the spindle, and fall straight down, below the ways.  Chip clearing at the cut is improved, and machine cleanliness in general is improved.

The slant also makes for a slightly more compact machine volume, front to back, because of the incline and because the carriage is on the back side where the motor is already taking up space, and not sticking out the front where your hands can reach the handwheels on an apron 

The other advantages, which have nothing to do with the slant layout, involve the use of linear guideways as opposed to V-ways.  This is just more a modern high tech development, basically extending the rolling vs. sliding concept behind ballscrews to the surfaces that constrain the linear motion of the axes.  The result is incredibly low friction (basically none compared to motor forces) and extremely low backlash/play in non-axis directions (which you only get from V-ways on larger/heavier machines with tuned up gibs).  With the unpredictable friction out of the way, it's now far easier to control the machine, especially at really fast travel speeds, which is how the modern fancy tooling centers can run hundreds of ipm cutting moves while dynamically playing with ballscrew forces to compensate for chatter or other cutting forces and achieve a perfect finish.

For the home builder (or commercial builder, I suppose) the advantage of these rails is that it's much easier & more straightforward to build a machine that is square & in alignment.  All I need to do is provide two roughly-correct sturdy surfaces to bolt the rails two in my frame, then face those contact areas in a larger mill or grinding setup, and then scrape or shim the rails to final tram upon installation.  No more pain in the butt V-ways that require lots of material removal in gigantic grinders followed by induction hardening, that also can't be replaced when they wear out much faster than the hardened ballbearing races.

The disadvantage, is that between the carriage and tool position, you really couldn't run one manually if you wanted to.  At best, it'd be a fly-by-wire system with no feedback, where you couldn't see what you are doing very well.  So it's really a dedicated/optimized CNC only kind of deal.  I already have a manual Chinese lathe for those jobs, and I learned a lot about what I can do with it, what I can't do, what I'd like to do going forward, and what capabilities I'll need to do that.  I want to be able to make Glock barrels from blanks & AR15 bolts from raw stock (not those exact parts necessarily, but those kinds of mostly-round widgets)

TCB


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## Eddyde

Wow, an awesome, ambitious project! I look forward to following this one, Thanks!


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## barnbwt

The current candidates for the stepper motors.  I could actually use some advice, or at least confirmation of my assumptions here;
-23HS33-4008D: 400 oz-in NEMA23 stepper, 5.66A bipolar parallel (2.83A serial), and 7.2mH/1.8mH inductance
-KL23H286-20-88-ALY:  same thing, but rated at 425 oz-in, 2.8A bipolar parallel (1.4A serial), and  6.8mH/27.2mH inductance

The vastly different inductance figures for each in parallel/series configuration suggests they are wound quite differently inside, despite the identical external profile.  From what I understand, the higher-current draw & much lower serial inductance figures of the first one suggest it's meant to run stronger at higher speeds than the second.  Now, seeing as I have limited current/power to work with, and the moving carriage is only ~50lb (20lb for slide), and the axis travel is not very large, I am looking at the second KL stepper in series configuration.  If I understand correctly, it may lack in power at speed (during rapids at hundreds of rpms), but would be just as powerful when resisting cutting forces & directing the cutter during turning moves, which require far lower speeds (tens of rpms).  I think this may be one of those cases where the greater serves for the lesser.

And the 24VDC power supply (ya'll be sure to let me know if I should run independent PS's for the stepper drivers & control boards);
-used Siemens 20A 24VDC power supply.

By my calcs I should never be running more than 13-14A 24VDC, and that's for the worst-case bipolar parallel stepper configuration.  This power supply, in addition to being overbuilt for the task as well as German in origin, is also much more efficient in how it uses its source power than the claimed figures I've seen from the only alternative; the Meanwell clones that are visibly 'lesser' in every way.  I figure the extra saved .5A is worth an extra 20$ or so for the used unit (even if I end up having to replace some ancient capacitors upon first powerup).  I'm told the greater _always_ serves for the greater when it comes to power supplies 

Servo drive showed up today.  It also looks like I'll need to add a cooling fan to the servo driver for sure, and probably also the stepper drives for good measure.  I figure if I'm gonna bother adding a 12VDC step-down line for the fans (there aren't a lot of cheap options for 24VDC) I might as well work up something for the motors themselves while I'm at it.  Maybe attach or integrate a heat sink & fan into the aluminum standoff the steppers mount to?  Maybe make that giant 3/8"-1/2" end-plate the servo motor bolts to out of aluminum?  The stationary items are easier to cool, just put a draw-fan nearby to suck the heat away.

TCB


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## barnbwt

I have decided to split the stepper drivers off into their own independent power supply for isolation reasons, since even steppers can dump current into the control devices when slowing down.  This also gives me the ability to run higher voltages for the drivers, for better high speed performance & torque control.

I have a proposal for my stepper driver setup for each axis I'd like to get some thoughts on;
For the Z-axis, use a nice Gecko-type driver that has both a high microstep count (my carriage travel is .001/full step) with smoothing, and high speed morphing to single-step so the longer axis has full rapid speeds.  Unless it breaks the bank, this drive would feature closed-loop encoder input capability for a later upgrade (not sure how important this is since the motion controller board will also have this feature for sure)

For the X-axis, use a much cheaper Chinese two-phase driver with minimum 16 division microstepping, but no fancy smoothing or high speed morphing functions, or even idle-current cutoff.  My thinking is the X-axis is always going to be nearly stationary for any lathe or milling operation, so the fancy motion control features won't be that useful, and the lack of 'sleep mode' will keep the stationary stepper fully energized to resist X-axis cutter forces at full holding torque (since the X won't be sent pulses at all during a simple profile move, for example).  I also found out they make cheaper rolled 4mm ballscrews, so I may go with the slower speed for this shorter axis vs. a more precise motor/control setup (though I'm torn since it is also the higher-stressed axis, and a 4mm screw is 1/4 weaker, 9.2kN vs 13kN, but still over 2000lbs capacity)

TCB


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## barnbwt

Another question that has occurred to me;
Besides the convenience of using ready-made ballscrews with their journal profiles already completed, is there any advantage to placing the preloaded/fixed end of the ballscrew at the opposite end from the motor-coupling?  It seems to me, that by placing this end at the lower end of the table, the loaded length of the screw is greatly shortened, resulting in a more rigid system (albeit only slightly compared to other factors).  The more common approach with the motor right at the fixed end seems tailored for CNC mill/lathe conversions, where the motor uses the space previously occupied by the handwheels, where there is also the structure to solidly mount the fixed-end screw support.  The slant bed is kind of backwards, in this regard.

TCB


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## cmantunes

If your budget permits, consider replacing the steppers with integrated servo motors, such as ClearPath. Not only will you get 6400 steps/rev if desired (w/ enhanced version) but the quietness, the smoothness of movement and lack of vibration will considerably enhance the build.


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## barnbwt

Of course a full servo-controlled closed-loop system on every axis would be nice, but that is far out of the budget for this project (hoping to keep it under $1500 for starters).  For now, I mainly want to make sure I am not boxing myself out of such an upgrade at some future date.  If I have problems with threading or engraving, I'd consider it.  A friend is running steppers & getting good results with engraving on his mill, but they are geared down 1:3 or so; it is possible the direct drive's reduced resolution & holding torque could be a limiting factor, in which case a precise/sensitive servo is a good solution.  I do think that simply going with a tighter ballscrew would get me most of what I'm looking for, for the time being, for not much money, though.

I spent today re-tweeking the frame a bit more; now the slide is 1.5" wider (basically 8" square), but I was able to tuck the ballscrew supports between the linear guide carriages, reducing the length of the carriage about 1.5" up where the stepper mounts, and bringing the lower edge of the carriage in by an inch.  Also added a horizontal stiffener bar to the upper end of the carriage (a section of 1.5" box tube) since the trench I had to mill for the X ball nut clearance left it U-shaped in a structural sense.  End result, the ballscrews are a bit shorter and now hidden, the linear rails didn't change much at all.




This means the depth of the machine can be reduced about 1.5", and now that I've also updated the models of the servo and stepper motors to be more accurate, I have a much better route to stiffening the headstock area to support the spindle.  Two X-braces three inches away from each other & filled by two thick shear plates should be crazy stout.

I'm pretty happy with the structural layout at this point, with only one possible, but unlikely modification; I think there is just enough room to put flip the stepper motors around and place them beneath the ball screws.  Instead of a fat block mounted to the ballscrew supports that mounts the motor, there would be a thick plate that hangs below for the motor face to bolt onto.  The idea of fully hidden motors is very appealing, and this would allow for some degree of gearing to a different ratio (namely on the X-axis).  However, I also believe it wouldn't be quite as rigid, both due to the belts and the cantilevered motor mount.  I'll have to think on it some more, and decide if it's enough to matter to the ballscrew.

TCB


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## barnbwt

Next round of stuff bought, pretty much everything but the bulk steel & electronics;
2X 400mm linear rails (X)
2X 600mm linear rails (Z)
300mm 1604 ballscrew & nut (unfinished) (X)
500mm 1605 ballscrew & nut (Z)
24VDC & 5VDC power supply
2X BK/BF12 ballscrew mounts
2X stainless steel 1/4"-10mm couplers

The cost this time was 408$.  Provided I don't go crazy with the motion controller, I'm on pace to squeak by under 1500$ in materials.  The first post will be updated with the particulars of these latest items.

TCB


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## rowbare

You have a great start here but I think there is some room for improvement. Note that I am not writing from practical build experience but from having followed dozens of build threads and absorbing comments from people who know more about this than I ever will. So take what I say with a grain of thought but please understand that I hope my comments will help shorten your path to success.

I think you need to bring up the stepper voltage considerably. Performance at 24 volts will be poor. Anyone who, like me, bought a Taig mill with an Allegro based controller running high inductance steppers should be able to attest to that. According to Gecko Drives stepper voltage should be 32 * sqrt(inductance) for best performance. Thus the first motor you listed wants about 43 volts and the second one about 83 volts (in parallel, series is much higher). I don't know what drives you are planning to use but the first motor draws a fair chunk of current so something like the Gecko G540 would be out of the question. On microstepping: its main purpose is to smooth out the motor at low speeds. It isn't the greatest way to increase resolution since the distance between microsteps isn't always even. There is a point of diminishing returns with microstepping. That is around 10 microsteps according to Gecko Drives.  See:  https://www.geckodrive.com/gecko/images/cms_files/Step Motor Basics Guide.pdf

As for the relationship between the motor, support block and screw, one of the roles of the support block is to isolate the motor from the violence of the screw. Support blocks have robust preloaded angular contact bearings while motors have comparatively wimpy deep groove bearings. With the mounting arrangement you are proposing, the motor will be subjected to all kinds of stress as the screw expands as it gets warm or if it starts to whip. In any case for short screws like you will here, you don't need to support both ends providing the screws are a sufficient diameter. The 16mm screws you are specifying are more than adequate. Look for the Critical Speed calculator on this page: http://www.nookindustries.com/EngineeringTool/Index to figure out what will work. It is interesting to note in their fixity examples, none has the motor opposite a bearing block.

I don't know where Mach 4 is at but Mach 3 has well documented issues with threading and dealing with index pulses (it can only deal with 1 per rev so it doesn't track very well). You might want to consider Linux CNC. It is more work to get going but is more robust than Mach 3.

If you have access to FEA software, run an analysis of your design. I think you will find that very little of the material above the spindle/bed plane contributes to rigidity. Take that part of your weight budget and put it where it will do more good and build up the enclosure. For instance, extra mass around the spindle and the spindle/bed interface is rarely wasted. 

Have you see this build? It is similar to yours: http://www.cnczone.com/forums/vertical-mill-lathe-project-log/281738-cnc-cad.html

bob


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## barnbwt

Absolutely right on the stepper voltage; I'm learning a lot and thought the drivers had a step up switch in them vs. just being a high-tech Morse code switch that passes current/voltage straight through when pulsing.  I think my servo drive is similar (really hard to tell what all it does, what with the multiphase conversion, voltage/current regulation, and pwm; I just know it's recommended for this motor).  I'm looking at some 60-80vdc supplies for servos, and possibly the 220 transformer I was hoping to avoid for the servo motor.

This really begs the question; why aren't there voltage step-up stepper drives?  Seems like it'd be nice to have the same adaptability you have for your output (current & voltage selection for different motors) on the input side, so you only need one big nice/regulated 24vdc supply unit, for instance.

I know what you mean about the screw mounts always being fixed at the motor end.  I suppose thermal growth is a very valid point, especially in big machines where they could get toasty.  My X is only 10" long, though, plus there's a spring on the end of it at the motor.  But by this same logic, there's no advantage to mounting the thrust bearing at one end or the other.  I suspect the wider footprint of the fixed mount may be a bigger factor for rigidity in supporting a cantilevered motor than anything.

The upper frame is intentionally overbuilt, but is 3/16" vs 1/4" thick tube.  I won't go thinner since I'm not a great MIG artist.  I plan to mount a tool carousel in there, and at this point I may be putting some/all of the electronics in a cabinet/hutch up there, possibly on a thick aluminum slab for heat conduction (servo drive requires a fan *and* a cold plate).  The lower frame will likely get heavier though; I am contemplating another tube along Z across the rail supports to better secure that critical plane against warp caused by the rest of the structure.  I only want to mill the rail seats planar once 

TCB


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## barnbwt

I'm sure my beer budget will dictate some changes, but at this point I'm thinking;
-Gecko G214 high-res stepper drive for X and Z axes (plenty of growth room for stronger steppers & closed loop in the future)
-80VDC unregulated linear power supply, 4A capacity qty(2)
-23HS33-4008D: 400 oz-in NEMA23 stepper (lower current usage for peak holding torque; speed is not so important)

Is the higher voltage itself an advantage?  I guess perhaps better second-order motor response due to electrons being pushed harder?  Neither velocity nor acceleration are as important for turning jobs, at least compared to static holding torque and smoothness (which is why servos would be ideal, if only they were affordable)


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## barnbwt

"Have you see this build? It is similar to yours: http://www.cnczone.com/forums/vertical-mill-lathe-project-log/281738-cnc-cad.html"
That build & dumpsterCNC were my inspiration (that poor guy lost everything to the tornado near Emory, Texas just a few weeks ago as I was first diving into this, otherwise I'd probably be pestering him with these questions, lol).  My hope is to scale that design down slightly, but not having that big box structure beneath the bed supports & above the bench top, and to make more efficient use of a small envelope with a stationary tool carousel (the tool holder will spin to index, and the carriage/slide will 'dock' with it to load & unload tools).  The servo spindle is more of an added capability than an improvement over the original design, meant to make this thing way, way, waaaay more useful than my manual lathe is.

TCB


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## barnbwt

A few more odds & ends, in anticipation of the servo motor's arrival & testing;
-High voltage connections, 8-pin & qty(2) 2-pin Molex connector terminal blocks; $5.78, $10.16
-Low voltage connections, 14-pin mini-Molex connector terminal block, 
-Encoder feedback connector, 15-pin D-sub; $18.87
-Encoder feedback connector, Fancy-pants mil spec 15-pin round bayonet connector; $46
-Computer interface, RS485 cable; $6
-Servo power cable; $52.98

The power cable is Keb brand, but the 8-pin round connector & insert arrangement appears identical to the Baldor.  I will probably end up buying a short length of shielded cable with 8 twisted pairs for the encoder line; while their prices are insane, Baldor was nice enough to clearly explain what is needed as far as the cable requirements in their installation manual.  Once I have the RS485 cable in hand I should be able to put 24VDC into the servo drive to turn it on, and talk to a computer via the (apparently crummy & poorly supported) Baldor Mint Workbench software, which is where I can play with step/dir gearing settings and so on.

One lame thing about this servo driver is the input pulse speed of only 1 MHz; with the 2500 line encoder on the motor, that's like 400rpm tops at 1:1.  Cost of doing business in 1998.  Through this software, I believe I can increase the encoder pulse/drive pulse ratio by a factor of ten (250 steps/turn) or greater and reach the top speeds desired.  I need to learn some more to find out if this is a setting that can be modified dynamically via M-code during a program; if that is the case, step/dir would definitely let me have my slow & precise cake and eat the high speed stuff, too.

Should I wish to run the motor in velocity (or even torque) mode via the analog signal, I may have some problems.  This drive responds to -10VDC to +10VDC signals, but all the motion controllers out there seem to be 0-+10VDC outputs, with relays that reverse the output poles for the opposite rotation.  Chapter 5.2 (no page numbers, Baldor?) of the manual linked below shows that the inputs can be set up as differential or single-ended.  I think that even if I reversed the polarity of the motion controller board output, I would have problems with the single-ended configuration, since the +10V lead would be hooked straight to a grounded terminal.  What I don't know is if putting +10V on that same ungrounded terminal for the differential configuration would actually work, or if its circuitry is still looking for a negative-to-ground voltage, albeit an unreferenced one.   There's an "internal reference" resistor on the circuit diagram in this area that could still be going to ground for all I can tell.

http://www.baldor.com/Shared/manuals/1919-803.pdf

I know enough about circuits to know some simple MOSFETery can pass-thru a 0-10VDC signal, or turn it into a -10-0VDC equivalent depending on a binary direction signal voltage & power supply, but I didn't see such a ready-made device amongst the other spindle-control doohickeys at the usual vendors.  If anyone has any suggestions I'm all ears, since I *suspect* interacting with driver settings via Mint Workbench as little as possible vs. external solutions is a good approach.

TCB


----------



## barnbwt

When I'm not torturing my mind with electrical/programming stuff, I'm working out the spindle for the next parts order.  Originally I'd planned to use a pair of opposed angular contact bearings at the business end, but I'm leaning more toward a single-race dual-row angular contact setup for a couple reasons;
-takes up less space & is simpler
-is more available in a shielded configuration
-50mm seems to be a very common size for HVAC uses (so much cheaper)
-plenty strong for any cutting loads the ballscrews can resist without damage themselves
-No PITA preload adjustment necessary once assembled

That last one is where I'm not so sure.  Not needing to squeeze the two halves of the support is nice, but I also worry that the loss of this ability is a bad idea for a lathe spindle.  It seems to work fine for A/C compressors, but who knows whether that has anything to do with the loads I'm contemplating?  Would the standard light pre-load bearing be rigid enough to prevent obnoxious acoustic patterns from fouling all parts turned at speed?  I suppose another solution would be to use two of these two-row bearings, and lightly tension them against each other similar to how we normally do the single-row jobs (possibly one at each end of the spindle)

https://www.vxb.com/3210-2RS-Bearing-Angular-Contact-Sealed-50x90x30-2-p/kit16655.htm

TCB


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## jbolt

http://www.practicalmachinist.com/vb/general/lathe-spindle-bearings-design-163580/


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## JimDawson

barnbwt said:


> This drive responds to -10VDC to +10VDC signals, but all the motion controllers out there seem to be 0-+10VDC outputs, with relays that reverse the output poles for the opposite rotation. Chapter 5.2 (no page numbers, Baldor?) of the manual linked below shows that the inputs can be set up as differential or single-ended. I think that even if I reversed the polarity of the motion controller board output, I would have problems with the single-ended configuration, since the +10V lead would be hooked straight to a grounded terminal. What I don't know is if putting +10V on that same ungrounded terminal for the differential configuration would actually work, or if its circuitry is still looking for a negative-to-ground voltage, albeit an unreferenced one. There's an "internal reference" resistor on the circuit diagram in this area that could still be going to ground for all I can tell.



Depends on the motion controller.  When you have a motion controller that will output a +/- 10 V signal, it is normally setup as single ended output, with the command signal going to the drive command input and then the controller ground going to the drive signal ground.  I have never done it, but setting up as a differential input might be the way to go in your case.

I would not think a relay switching the command signal polarity would be very fast system, but maybe it works.  I guess for the spindle, it wouldn't really matter.


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## barnbwt

Well, it is for velocity/torque control & not position; I can't imagine needing to rapidly vary the speed instruction at speeds beyond the step/dir regime.  I also think the negative values are for reversing the spindle (not simply slowing it) which would be an even odder command for an already-turning machine.


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## barnbwt

Thanks for the link, jbolt, lotta material to go over there


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## JimDawson

barnbwt said:


> Well, it is for velocity/torque control & not position



While you are correct it is for velocity/torque control, but it positions quite well also in velocity mode.  Just requires a closed loop and a motion controller designed for that system.  Up until the new digital ModBus systems were recently developed, it was the defacto standard for most industrial CNC systems.  It is still shipping on new machines today.  With the proper stepper drive it is also possible to drive a stepper in velocity mode with an analog signal.


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## cmantunes

barnbwt said:


> This drive responds to -10VDC to +10VDC signals, but all the motion controllers out there seem to be 0-+10VDC outputs



Have a look at ADCGAIN and ADCOFFSET on Mint Workbench help file. Together with a digital I/O pin, you may be able to adjust these on the fly. Depending on the state of the digital I/O, you would set ADCGAIN equal to 100 or -100, for example.


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## barnbwt

Just wanted to post something useful for anyone else hoping to cobble together a servo system: M23 connectors.  Apparently this is the standard 'servo cable' standard connector in the industrial world, as opposed to something that's mil-standard and searchable.  These have 23mm x 1mm cap threads, hence the name.  What's nice about these, unlike the mil-std connectors, is there are only a handful of insert arrangements, which made it really easy to figure out which one I needed (the 16-pin one).

Moreover, these connectors are widely available on places like ebay or alibaba, some already in cable assemblies, for a fraction of the cost of even used "name brand" harnesses.  So in summary; if you need a circular plug for a servo motor, PLC, or other industry-type automation, check out the M23 series along with whatever other hunches you suspect it might be.

TCB


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## Karl_T

Great project.I will follow your construction with great interest.


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## barnbwt

I see Karl_T tracked me down here as well...I hear from yet another forum's ancient posts, that you know about Galil motion controllers..?

Just some updates on the design's progress:

I've settled on my spindle bearings; working end will be a pair of 50x80x16mm 7010 P4 angular contact bearings, tail end will be a more pedestrian single 6010 deep groove bearing (a lower tolerance variety, since super-precision DG bearings are crazy expensive for some reason).  Total cost seems to be about 250$ for all these, so a bit higher than I'd hoped, but probably worth it.

I think I've also figured out my spindle cartridge assembly (I want it to be easily serviceable since I predict fixing/tweaking will be needed at least once); AC bearings will press in from the working end against an internal shoulder & be captured by a bolt-on cover plate, two spacers (with integral grease shields) will insert from the rear against each set of bearing races and the sealed DG tail bearing will cap them off.  At that point, the spindle shaft can be pressed through all three bearings with their inner races supported from the tail by the coaxial spacer, and the rear of the D1-4 mounting flange will nest into the cover plate to form a labyrinth seal.  Once fully seated, the drive pulley can be keyed into place, and a jam nut will compress it against all the inner races.  To disassemble, the outer race is pressed from the tail, the coaxial spacer pushing the AC pair out the front.  Once they are freed, the jam nut is removed and the pulley & shaft slipped out.  From there, the outer coaxial spacer can push the tail bearing back out the rear (likely not a tight press as with the AC bearings in any case).

It seems like it's simple & easy, but I dunno.  My other thought was to have a simple single-diameter thru-bore, and have the AC bearings come up against a spacer sleeve that's fixed in the outer casing by set screw(s).  At that point the whole mess could be pressed in/out from either direction before the shaft components are dissected by bearing pullers.  Both seem equally non-adjustable for pre-load between the AC & DG bearings, but my thought is it may be unnecessary by virtue of the matched AC pair (at which point the spacers are simply there to aid in assembly/disassembly and to act as grease seals)

I've also been doing (a ton of) research into the electrical side of things; it appears I am at a fairly significant crossroads that will determine how I proceed.  What I know for sure, is that I'll be running my servo amp in +/-10V analog "Velocity" or "Torque" mode (as opposed to step/direction, since those use different outputs on the controller & would require a physical switch & software reconfiguration every time I need to switch from spindle mode to axis mode)

Open-Source Solution: 575$
-Laptop PC (2.6GHz i7, ethernet E100 connection to controller)
-Linux OS
-LinuxCNC interface/G-code interpreter
-One of several open source GUI's
-Mesa 7i92 main board
-Mesa 7i76 stepper drive interface
-Mesa 7i77 servo drive interface

Junkyard Solution A.1: 575$
-Laptop PC (2.6GHz i7, ethernet E100 connection to controller)
-Windows XP (do emulators work?)
-Mach3, with Galil driver/G-code interpreter
-Used Galil 21xx motion controller
-Phoenix labs terminal block/breakout board

Junkyard Solution A.2: 1000$
-Laptop PC (2.6GHz i7, ethernet E100 connection to controller)
-Windows 10
-Mach4, with Galil driver/G-code interpreter
-Used Galil 41xx motion controller
-Phoenix labs terminal block/breakout board

Junkyard Solution B: 1000$
-Laptop PC (2.6GHz i7, ethernet E100 connection to controller)
-Windows OS/Linux OS
-LabWindows interface (and theoretical G-code interpreter)
-NI Motion GUI
-National Instruments FW-73xx motion controller
-NI Breakout panel

Pro/Cons:
Open Source Pro: likely to be supported & receive future development, highly modifiable/configurable
Open Source Con: laptop may have latency issues, does not appear to support articulated spindle-servo at this time (maybe)
Junkyard A.1 Pro: community knowledge of Mach3, Galil driver/interpreter is available but no longer supported
Junkyard A.1 Con: Galil driver is a bit antiquated, Mach3 company support is ending, I'm not sure if it supports articulated spindle
Junkyard A.2 Pro: Mach4 has more capability, Galil driver/interpreter is available & supported/developed, modern contour cutting mode
Junkyard A.2 Con: Cost, mostly, the added capability may also be totally unnecessary for my machine
Junkyard B Pro: currently supported, likely will continue to be since Labview is fairly common in universities, I think is highly programmable/configurable
Junkyard B Con: the motion-control side of NI seems surprisingly obscure, not much info out there to help set up a new system (let alone designing one), also cost

I welcome anyone's experience with any/all of these servo control solutions!

TCB


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## Karl_T

I just read your thread over on CNCzone...  I've been a member there for more than ten years but don't go there often any more. Just found out my log in is no longer valid.

I've used Galil controllers exclusively on my CNC machines since about 2002, Mach2 before that, a DOS based stepper control (AHHA) before that. I certainly agree with Jim Dawson that a Galil controller is by far your best option. My understanding, Mach 3 over Galil just does not work well. I've only scanned the topic but mach 4 over Galil is not quite ready for prime time. Maybe you would like to be on the bleeding edge of technology here?

This is an overall comment from scanning the other thread:
Galil will run that servo spindle at 4000 RPM and index the spindle to the correct orientation. BUT your holding torque will be totally inadequate for milling. You could install a large brake. Maybe I'm missing something here on your project.


As an aside, I use Camsoft CNC controller. Its designed from the ground up to work with Galil. Its out of your price range at about $4K for the software. Worth every penny for challenging applications.


----------



## barnbwt

> I certainly agree with Jim Dawson that a Galil controller is by far your best option. My understanding, Mach 3 over Galil just does not work well. I've only scanned the topic but mach 4 over Galil is not quite ready for prime time. Maybe you would like to be on the bleeding edge of technology here?


I think I'm doomed to being a bit bloody regardless, since I don't think anything but the 4000$ software jobs like Camsoft are turn-key.  My understanding is that Mach 4 will be/is extensively developed for newer Galil controllers, but older ones are basically being left SOL since neither Mach3 nor the drivers will have continued support apart from hobbyists (who will trend more toward Mach4 in the coming the years).  Apparently the ability to rapidly feed-forward large numbers of moves (the real meat of the 'contour mode' technology in newer drives) is a real dividing line between new & old equipment, and it appears the world is moving on from the legacy way of doing things.  So I think I'll pass on the Junkyard A.1 Mach3 configuration, I think it will end up being too constraining (the fact I'd have to run XP is already pretty ridiculous, frankly)

"Galil will run that servo spindle at 4000 RPM and index the spindle to the correct orientation. BUT your holding torque will be totally inadequate for milling. You could install a large brake. Maybe I'm missing something here on your project."
My first goal is to get engraving working, and maybe small keyways; I'm really not capable of running a strong enough servo *and* live tool to do real milling in any case, simply due to my electrical supply constraints.  If I can engrave/follow a complex surface with the tool I'll be happy (think a pyramidal form, or a shaft with a 'Pringle' surface on its end).  I never planned on having anything bigger than 1/8" cutters in the mix, and probably ball-ends at that.

Once I get a better 30A power supply, then I'd be more interested in upgrading to a tougher motor, and a real live tool setup (as opposed to a Foredom or Dremel).  I've seen some folks run a second worm-drive spindle "bull gear" that can be engaged along with spindle encoder or indicator, but the complexity & bulk associated with that is really something I'd rather avoid if possible.

If I'm going to the trouble of doing a single servo, it's not that much harder to also run a closed loop on the X & Z axes (and it looks like the prices on the encoder "servo-stepper" kits from China have come down a good bit).  Or even real servos with a reducer gear (since they're about 1/4 the torque of similar-wattage steppers).  Once again, it's really easy to add expense to this project, but with closed-axes, I wonder if one could actually program a "soft feed" that allows the spindle to stall a bit while cutting, but adjusts the other axes forward/backward along the toolpath until metal is removed & it can proceed?

TCB


----------



## JimDawson

barnbwt said:


> Once again, it's really easy to add expense to this project, but with closed-axes, I wonder if one could actually program a "soft feed" that allows the spindle to stall a bit while cutting, but adjusts the other axes forward/backward along the toolpath until metal is removed & it can proceed?




I think that could be done with a closed loop system by gearing the axes together.  Might require some experimenting. Mach3 will not do it, even with a closed loop system, Mach3 is still open loop.  Mach3 has no idea what the machine is doing or where the axes are actually at.   I'm not sure about Mach4, but I suspect that it works the same way.  If the table is not where Mach3 expects it to be at a given time, Mach3 just plows ahead with the next commanded position anyway.  Any error correction programming would have to be done at the controller level.


----------



## barnbwt

Ah, very good point; in that case something like LinuxCNC should have the edge, since the HAL or whatever is in direct (two-way?) communication with the I/O boards with no middle-man if I'm not mistaken.  A cursory search suggests even Mach4 cannot close the loop at the software-interface level, because Windows is not a real-time OS (but LinuxCNC is)

I do wonder if the Galil could lend some aid in this area, since it's where the real-time synchronizing occurs.  The box is in direct contact with the drivers/encoders so it knows where the axes are, and could report back to the controller software whether or not it has reached the desired waypoint, prompting the controller to send the next line or to wait for it to recover (or even walk backward through the code if pushed back to the previous waypoint along the current vector, instead of sending the next destination).  Not unlike a software download manager doing checksums & handshakes if you think about it.

EDIT: Apparently that badass Vital System DSPMC supports fully closed-loop operation.  They say for backlash comp, but I suppose that's essentially what I'm describing as far as a non-rigid spindle axis (it'd be gear lash in a worm-driven 4th axis arrangement as opposed to servo-stall)


----------



## rtp_burnsville

Thanks for posting......  My next project is going to be a CNC lathe so your timing is great.  I was thinking about the typical Chinese conversion as there is an extra 7x10 sitting on the bench, but your approach looks more interesting.  I have looked many times at the Tormach lathe (while I like my 1100 mill) but think it is vastly over priced so the DIY approach appeals to me.

Thanks,
Robert


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## rtp_burnsville

You mention LinuxCNC.....  I have been rather impressed with the operation of LinuxCNC on the Tormach mill over the past couple of years.  I would certainly think it would be worth a look.  It takes some messing around to get a non-supported machine up and running but their forum has some great followers that would get you pointed in the the right direction.  

Robert


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## Karl_T

My two cents. The work you are considering is duck soup for a fourth axis on a mill. Any of your four routes would work. For hardware just add an indexer with a drive belt to a servo or stepper motor.  Pic of mine attached, its plenty robust to run a 1/2 endmill in steel.

If you drop lthis from the lathe project, now it becomes simple also, any of your choices would work.

Lots of people have done both these projects, you won't be breaking any new ground.


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## barnbwt

I already have a manual lathe, but no mill in which to cut keyways/splines, or even do engraving.  It'd be nice to make candle holders & chamber reamer profiles, but I can do that already more or less on the manual.

Call me greedy, but given the difficulty, uncertainty, and expense of a homebuild, I'd like a significant addition to my capabilities.  Even if the servo isn't strong enough now due to power restrictions, the capacity to swap in a bigger unit & have it work within the system at a future date is desirable.

Checking into it, it sounds like any worm arrangement I am likely to make will have a lot of backlash, unless there's some trick to that.  I'm not seeing how it would be superior to a servo spindle.  Swapping in a bigger/faster drive & gearing it down seems like a better move (even though the gearing complicates some things)

TCB


----------



## barnbwt

Alrighty, next series of major purchases has been made;

Galil DMC-2183 8-axis motion controller
Galil SDM-20640 4-axis stepper motor driver daughter board

So while the wallet charges back up, I am now looking at the next link in the chain; stepper motors!

My design constraints are at least well-defined since I have a driver circuit to work within, which is kind of backwards from how you're supposed to approach this.  The Galil driver is certain to be 'good enough' for my rather modest means, so it's down to milking the most I can out of it for the money --same as everything else so far.

1) Driver current is 3A maximum:
This effectively puts a cap on the amount of torque I can get from my motors.  Every motor winding design has a different torque:current ratio, but peak torque is always attained at peak current (and at slow speeds).  According to materials on Gecko's site about sizing servo power supplies, the bipolar-parallel winding configuration my steppers will use can only draw at most 2/3 of the rated current in practice (I think the rated value is for a *stalled* motor condition, which a good machine design won't operate them in).  Unless I'm mistaken *--please tell me if I'm mistaken-- *that means my 3A driver circuits can run 4A steppers at most, and I'd need a +8A power supply to feed them.

2) Driver voltage is 50V maximum:
Voltage limits put a cap on how fast you can go, and also what types of motor windings can be used.  Current is held to a fixed level during the peak/constant torque portion of the motor's performance so the windings don't fry, and since torque & speed correspond to power, a higher operating voltage capability means higher speed before torque falls off (i.e. current drops due to impedance effects at high speed).  To get the most from my drivers, I need power supply that can operate at around 48V (50V isn't as common, is all)

48V isn't super energetic, but it is high enough that it can damage certain stepper motors (it can drive current too hard into a coil that isn't build with enough inductance to resist it) or at least cause them to run poorly, and hot (more likely with only 3A to play with). Going by the voltage-rating formula out there in many places (Vmax = 32*sqrt(inductance)), it appears that if I wish to use the full 50V capacity of my driver for power output, I must use motors with impedance near 2.44mH, or slightly higher.  If much lower, the motors will cook at 50V, if impedance is much higher the stepper driver's voltage won't drive the motor aggressively enough to operate at higher speeds (torque falls off badly)

3) Motor wiring is bipolar-parallel:
There's three ways the two sets of coils inside the motor can be hooked up to power and driven; bipolar series, unipolar, and bipolar parallel (in rough order of increasing torque rating).  From what I gather, unipolar is an archaic configuration that older drivers were designed around, before more modern switching circuits became available; they can still be wired as series, or as parallel (but only using half their coil turns), but we generally can't drive stuff in unipolar wiring anymore.  That leaves series and parallel, and is basically a function of how much speed you need; series can be driven at low current, but has very high inductance so lots of voltage is needed to spin the motor quickly (more than any driver can supply).  The trade off is not equal, so unless you don't have much current *and* don't need speed, bi-polar is more efficient all around.  For simplicity, this is the only motor configuration I'm looking to use.

I've already found a reasonably-priced 48VDC power supply that can deliver up to 9A.  *So, I'm looking for bipolar-parallel motors in the 3-4A range with impedance around 2.5mH.*  *Not* looking at torque figures except for comparison (like I said, I'm having to do this a little backwards  ).  If any of you know of some vendors that have a good selection, I'd like to hear about them; checking out the OMC/StepperOnline catalog, there are a plethora of NEMA23-size stepper motors in all manner of power levels, but I'm not seeing that 'perfect' combination of my design requirements that will let me get the most out of my machine.  If I have to compromise on anything, I think it should be high impedance since that mostly affects high speed operation, and as I've mentioned, lathes don't gain as much from rapid traverse moves as do mills and routers.  My target rapid speed of 420rpm is less than half the 1000rpm that the inductance figures are measured at, but I don't know how much lower they would be.

Here's my list of hopefuls;
(I'm also listing inertia to get an idea of the 'agility' of these motors)
24HS34-4004D; 35$, 4A, 3.5mH, 325.7oz-in, 840g/cm^2 **NEMA24** my understanding is these still roughly fit the NEMA23 form-factor, which is fine)
23HS45-3004D; 75$, 3A, 9.0mH, 354.0oz-in, 810g/cm^2 (inductance is rather high, by my 'rapid speed' rpm is only 420rpm, so maybe OK...price is silly)
23HS45-4208D; 75$, 4.2A, 2.3mH, 276.1oz-in, 810g/cm^2 (would have to run at slightly-lower torque at all speeds, but curve is flatter...price is silly)
23HS33-4008D; 25$, 4A, 1.8mH, 283.2oz-in, 530g/cm^2 (I'm limited to around 42V and less power, but torque/inertia ratio is much higher)
*this last one is the front-runner, unless my assumptions are bad or there's a better option

There's lots of others, but this 4A/3mH region seems to be a bit sparse.  Tons of options one amp higher, or if I had 80V to drive a higher-inductance motor with, but these are the only options I have unless I want to step down to <250oz-in torque ouput (probably still okay, but why not get more if it's available?)

TCB


----------



## barnbwt

I found a fifth motor, I think it may be 'the one'
23H2100-35-4B; 40$, 3.5A, 2.8mH, 381oz-in.  Seems just about perfect; near full-rated current, very close impedance match to 50V, and not insanely expensive.  These also appear to be a favorite of the G540 Gecko users (which makes sense because that also has a 3A limit, but at 80V)

I've also started putting my electrical block diagram together, in advance of firing up some of these components for testing (see attached).  One slight hiccup that I decided to take on is that the Galil controller & daughter board do not hook up as they are currently configured.  The secondary board is meant to snap onto the top of the main one via a 96pin DIN connector as well as some secondary pin blocks, but the DIN on my 2183 unit is the right-angle variety; no va.  So now I'm looking into connecting the two via ribbon cables (which seems noise prone) or going all out & removing/replacing the right angle connector with a straight variety (which costs like 3$ for five pieces).  Seems like both routes will cost me ~60$ in either wires or soldering tools




While that copper-based mess is percolating, I'm also finalizing the spindle cartridge design.  I had been planning to use 50mm ID bearings, but I've decided to go with smaller 45's since they are apparently half the price for a marginal reduction in spindle thickness (still about .19" thick walls).  This has enabled me to acquire proper P4/ABEC7 super precision spindle bearings for both the nose and tail sets, unfortunately neither are sealed so I am working out how best to protect them from swarf & coolant.  My plan is to have a labyrinth seal at each end of the cartridge (more complex at the nose-end), and two internal grease baffles/slingers near the bearings to help keep the grease stay put in operation.  Also one Zerk fitting next to each bearing set for the occasional squirt.




The cam-lock spindle complicates the seal arrangement since the mounting cam holes are so big, but at least with the narrower bearings there is now room for a small series of labyrinth ribs.  In practice those holes will be filled, but they will still allow debris to ingress to some extent during chuck changes/etc.  To be honest, I'm having second thoughts about the D1-4 capability altogether; it makes the spindle large & expensive, eats some precious bed length, and most worrisome, I'm having doubts about its utility.  Being inside the machine, manipulating the cam-locks chuck jaws will be highly annoying, and I'm not sure that the ability to mount 3 or 4 jaw chucks is all that useful in a CNC slant bed like this, where the vast majority of jobs will be single-setup operations held in a collet/closer.  You can even mount ER40 collets in a 5C with an adapter, so my need for that ability is satisfied.  Still, the ability to use all my current D1-4 accessories (3-jaw, 4-jaw, ER40 collet chuck, face plate [which may not even fit through the door, lol]) is somehow tempting.


TCB


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## barnbwt

Another paycheck, another step toward completion...

Today I ordered the spindle bearings;
-Barden 209HCDUL matched P4/ABEC7 angular contact bearings
-Fafnir MM209K CR P4/ABEC7 deep groove ball bearings

Both are wildy in excess of what I need as far as load capacity & especially rated speed, but only cost about 50$ than the less-precise P5/ABEC5 equivalent on the new-old-stock market (eBay).  From what I can tell, class 5 is about as low as you ever want to go for a spindle, since the rated speed and service life fall drastically; unless you are running at car-tire speeds of several hundred rpms, they simply generate too much heat & introduce too much variation at the cutter.

I had what I thought was an interesting idea regarding Karl's comment about weak holding torque for milling operations.  Obviously a brake of some kind is the logical solution, but I was concerned its creation would add significant complexity to this already ambitious project.  Then I remembered those little disc-brakes that have taken over the bicycle industry the last several years; they come in sizes from 140mm to 203mm and it's only a couple dozen dollars for a rotor/caliper setup that is ready to bolt-on as you wish.  More expensive hydraulic versions are out there, but the simple pivoting-clamp type pulled by a cable would be sufficient for my needs, and would be very simple to control with a solenoid (that, or mount a bicycle hand lever on the machine, lol).  So I may end up adding a brake disc rotor next to the drive pulley for this purpose.  I would think this direct-brake approach would be more rigid than a brake mounted at the motor shaft, too.

And thinking about it some more, since these pads/rotors are designed to actually work while in motion (unlike most servo brakes) and the replacement wear parts are so cheap, this could potentially work as a generic spindle brake so the inertia doesn't have to be dissipated through a braking resistor (I'm guessing this requires some more development on the programming side)

The next major acquisition is likely the 48VDC power supply and stepper motors; after that it's all steel (finally).  In the mean time I will be designing & building the wire harnesses I need to begin testing the electrical components.

TCB


----------



## Karl_T

You won't need this for a while, but I'll offer it now. The attached program would work real slick to jog your machine. I mention it now cause it uses inputs on the Galil card. You would need seven to do three axis. I'd suggest keeping two or three more inputs and a spare axis to do your MPG handwheel entirely inside Galil.  FWIW, a top quality JOG and handwheel really improves setup quality and time.

I'm a fairly accomplished galil programmer, if you ever need help.


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## barnbwt

Talk about putting the cart before the horse (or is it pearls before swine, lol)!  Thank you regardless; at least as far as the logic side for the jog script, it's comforting to more or less understand what I'm looking at.  I need to study up on Galil machine code a lot more before the homing routine will mean anything to me.  At least this language doesn't require a labyrinth of GOTO commands to do anything (a crusty old prof made us learn FORTRAN for his class --in 2010!)

A buddy has his CNC mill outfitted with an XBOX controller for simple positioning/indicating during setup, and I agree it makes things a lot easier than driving the table strictly by numbers in Mach.

TCB


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## Karl_T

I considered Fortran an advanced language in 1972. the prof made us learn machine code and assembly language first. I was an early programmer of automation robots, where GOTO meant move the robot to a certain position or point in 3D space.

The homing function does not work with steppers, you need a "Z" index pulse. Just one of the reasons i never use steppers any more. Main reason is no feedback, but Mach won't accept feedback anyway. And that's why I don't use Mach.


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## barnbwt

By index pulse do you mean an actual encoder feedback, or just a once-per-rev deal?  I plan to use dual-shaft steppers so that encoders may eventually be added, or maybe even NEMA23 servos if I ever get enough electric capacity and the funds to buy them & the necessary gearboxes.  Z-axis could actually run a NEMA34, but it'd be a bit much to hang on of those off the back of the poor saddle, lol (maybe with a right-angle worm drive I could pull that off)


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## Karl_T

Z or index pulse is part of the encoder. Its a pulse once per revolution.  I think, but not sure, that you could home the machine with encoders attached to steppers.  Homing is a three step process - rapid to home switch - slew speed to Z index mark on encoder - creep back off index mark.


----------



## barnbwt

I've decided to ditch the D1-4 spindle flange feature, and do a 5C only.  I was really tempted to do a 2J collet system since there's a lot of stuff that needs just a tiny bit more capacity than what fits through a 5C, but I have to draw the line somewhere.  Plus this way I get to use much cheaper 45mm bearings and a far smaller spindle profile.  Compare;



The spindle shaft goes from 4.5" diameter to 2.0" diameter, and 9" length to 7.5" length (all 1.5" shifting the collet taper closer to the bearings, and out of the work envelope).  I also changed the square mounting flanges on the casing to round ones so I could add more mounting bolts and true them up on the manual lathe once welded.

I still not entirely happy with the tail-end labyrinth closeout plate, since I feel its thin profile and large diameter are a recipe for vibration.  It's not meant to be a proper fly-wheel, but I am considering the benefits of making it one to help dampen cutting vibrations and function as a brake rotor.  The added inertia seems to be both a blessing and a curse in certain ways.

I now plan to mount the future 4-5 position tool turret directly to the YZ table since there is more room in the cutting area.  With a max 5" swing radius available, I'll mount a double ball nut on Y to reduce backlash/chatter in that direction & lose the extra inch of motion that I'd planned on using to dock with a fixed tool changer.  Except for really long boring tools or large parts, there should be ample Z travel to move the carousel out of the way of the workpiece to spin.

The spindle bearings and 48VDC power supply have been acquired, so the only thing left is steel and cabling, and lots of work.  There was a change of plans on the AC bearings; they are now a medium-preload NSK7209A5TYDUMP4 because of a somewhat misleading ad (the previous part was pictured as a complete matched pair, but was being sold in halves for some dumb reason).  The NSK's seem just as nice if not moreso on the exterior, and were the same price as the 'half' Barden set.  The medium pre-load is overkill on my machine, but even if I do pre-load them to spec the top speed is still within my limits (I'll probably under-load them simply to reduce friction load on the spindle motor)

So, lesson learned on bargain AC bearings; since there's lots of orphaned bearing halves out there that sellers will list with the original box, it's easy to get fooled unless you look/read closely.  I got lucky & am only out return shipping, so no harm no foul.

TCB


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## barnbwt

NVM


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## Karl_T

Your headstock design is now virtually identical to a hardinge lathe headstock. These are built solid as a brick sh*t house with a brake and 5C collet closer. The headstock bolts right on to the lathe ways, so it could bolt right up to a slant bed. The ground spindle also takes hardinge lathe chucks - 3 jaw, 4 jaw, step 5c chuck adaptors.  I have one - someplace - but scrapped hardinge chuckers are common.

The listing shows the headstock
http://www.ebay.com/itm/Hardinge-DV...ardinge-Turret-Tool-Cross-Slide-/132236584966

same headstock on a dozen models


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## barnbwt

Okay, back on this project after a long absence, new town, new career...

As I reexamine the progress I had made, it looks like one of the more obvious 'gaps' in the plan is the leap between the software I will be using to generate my G-code commands (Fusion 360) and the Galil motion controller (DMC 2183).  Galil uses DMC language rather than G-Code, so something is needed to bridge that gap, unless I'm missing something.

A compiler & post processor native to Fusion that outputs DMC would be the most direct option, but I'm positive nothing like that exists.  Which is a shame since older affordable Galil controllers are so plentiful, but still capable of impressive control.  Seems right up the alley of the Fusion user base, which are basically cheap bastards willing to put in some elbow grease to get the job done for a lot less money


----------



## JimDawson

barnbwt said:


> A compiler & post processor native to Fusion that outputs DMC would be the most direct option, but I'm positive nothing like that exists.



Nope, and it would be almost impossible.  You need a translator and user interface between the G code and the controller.  There is a lot of stuff going on behind the scenes.  

You took a break from this project at about the same time I picked up the Hardinge CNC.  That was actually good timing.  I now have my software running on the Hardinge.


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## barnbwt

(continuing the conversation from CNCzone) I think I've read some of the thread(s) on that build, but somehow I'd missed the more recent updates; I'll peruse those next in the coming days.

So I guess for Fusion to talk directly to the Galil, you'd need a ridiculously sophisticated post-processor to handle all the setting & configuration options defined locally in the controller?  Maybe I'm still a little confused about exactly what data is being sent to the controller and how it differs from the G & M code commands put out by the post-processor.

Oh, another question I just had; do these controllers (the 21X3 series anyway) run commands near-real time as they are fed to them via ethernet & a small local buffer, or are they preloading large chunks or entire programs to local memory and only running standalone?  Does the computer with your CNC interface hooked up to the controller "do" anything while the controller is executing DMC code?


----------



## JimDawson

barnbwt said:


> (continuing the conversation from CNCzone) I think I've read some of the thread(s) on that build, but somehow I'd missed the more recent updates; I'll peruse those next in the coming days.



That was an interesting project. 



> So I guess for Fusion to talk directly to the Galil, you'd need a ridiculously sophisticated post-processor to handle all the setting & configuration options defined locally in the controller?  Maybe I'm still a little confused about exactly what data is being sent to the controller and how it differs from the G & M code commands put out by the post-processor.



There is a lot of configuration and other functions going on in the CNC program.  Assuming it was possible to create a post processor that would output DMC code directly, it still would not run the machine.  You still have to deal with the tool offset tables, cutter comp, and a number of other things that the Galil does not do.

Each of the G and M functions have a corresponding sub-program in the Galil non-volatile memory.  To do a tool change for instance requires about 50 lines of DMC code.  But it is called by sending single line command, giving it the new tool number and telling it to execute that sub-program.  ''NEWTOOL=5;XQ#M6,3''



> Oh, another question I just had; do these controllers (the 21X3 series anyway) run commands near-real time as they are fed to them via ethernet & a small local buffer, or are they preloading large chunks or entire programs to local memory and only running standalone?



There is a 512 line x 80 character buffer that streams the linear interpolation commands to the Galil.  It will keep going as long as there is data in the buffer.  It's the CNC program job to keep the buffer full for smooth operation of the machine.



> Does the computer with your CNC interface hooked up to the controller "do" anything while the controller is executing DMC code?



It monitors a lot of housekeeping activities, keeps the DRO updated, provides needed messages to the operator, and of course keeps the command buffer full, and sends commands as needed.

EDIT:  I might add that unlike any other CNC program that I'm aware of, you can also surf the net, or work on drawings while the machine is making parts.


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## Karl_T

There is one GREAT, but expensive option. Camsoft is designed from the ground up to use CAM generated gcode and run Galil cards. It is the only thing I use on two CNC lathes and two CNC mills.


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## barnbwt

JimDawson said:


> That was an interesting project.
> 
> 
> 
> There is a lot of configuration and other functions going on in the CNC program.  Assuming it was possible to create a post processor that would output DMC code directly, it still would not run the machine.  You still have to deal with the tool offset tables, cutter comp, and a number of other things that the Galil does not do.
> 
> Each of the G and M functions have a corresponding sub-program in the Galil non-volatile memory.  To do a tool change for instance requires about 50 lines of DMC code.  But it is called by sending single line command, giving it the new tool number and telling it to execute that sub-program.  ''NEWTOOL=5;XQ#M6,3''
> 
> 
> 
> There is a 512 line x 80 character buffer that streams the linear interpolation commands to the Galil.  It will keep going as long as there is data in the buffer.  It's the CNC program job to keep the buffer full for smooth operation of the machine.
> 
> 
> 
> It monitors a lot of housekeeping activities, keeps the DRO updated, provides needed messages to the operator, and of course keeps the command buffer full, and sends commands as needed.
> 
> EDIT:  I might add that unlike any other CNC program that I'm aware of, you can also surf the net, or work on drawings while the machine is making parts.



Okay, I think I get it now; I was a little soft-headed there, I think.  Most of my experience is in CAD and CAM, not machine operation.  Obviously a post can't perform the control, monitoring, and display functions that the operator panel does.  Can't indicate a tool via CAM software output


----------



## barnbwt

Karl_T said:


> There is one GREAT, but expensive option. Camsoft is designed from the ground up to use CAM generated gcode and run Galil cards. It is the only thing I use on two CNC lathes and two CNC mills.


So, what's the relationship between Camsoft & Galil?  Are they simply designed to work together, Camsoft the software side, Galil the hardware side, of machines built by the same folks?  Or is Camsoft ported to a bunch of machines, including Galil (hence the cost, I imagine)?

I'm aware that Camsoft is very powerful (not that users don't still complain about it) but I don't know why they seem to have such exclusivity with the Galil controllers, which are after all fairly common and a good all around option for high quality budget jobs --except for the incredibly expensive software control.


----------



## JimDawson

barnbwt said:


> ............ but I don't know why they seem to have such exclusivity with the Galil controllers



I think I can answer that.  They could have chosen to go with Delta Tau, G&L, Rexroth, Dynomotion, or any number of other motion control products.  They probably had experience with Galil so went that direction.  Each of the motion controllers that I mentioned would require a whole different set of software interface modules to be developed.  Since this is the core of the system, it would be a major and time consuming effort to write software for each controller.  Of the ones I mentioned, Galil is the easiest to work with, and I have written software for all of those.  From a programmer perspective there is a long learning curve (months at best) associated with each controller.

My software would not work with any controller other than Galil products without a major rewrite.


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## Karl_T

Camsoft is optimized for use with Galil and servos. They do have a stepper box - stupid to go this way IMHO - no closed loop control. They also have their own proprietary servo card. It is less expensive than galil. I have not used it, but think a lot of functionality is lost. 

Camsoft's other strength is interfacing with a number of I/O products and logic programming. Makes a PLC look like a toy. Galil is somewhat limited here. The real time motion control of galil and the logic control of camsoft is a powerful combination.

At one time there was another company with a PC host interface for Galil similar to what Jim has done. But they went out of business.


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## barnbwt

I understand the significant commitment of resources needed to get one of these interfaces programmed & running; it just seems like Galil has limited itself by operating sole-source through Camsoft.  It's not like they would sell fewer motion controls --new or used-- if they'd developed an in-house alternative that functions off of standard post-code like DC_CNC can.  I suppose it just wouldn't be any cheaper than CamSoft, is all.

I scored a rather good deal (by my estimation) on a controller to replace my mis-matched set; another Galil 2183, but fitted with the 20640 stepper board as well as a 4-axis servo drive board.  All for less than I'd paid for the first 2183 with the incorrect daughter board connector.  Evidently the daughter boards must be connected & configured at the factory, it's not something that can be done through Galil's publicly available configuration utilities.  They really need to be more clear about that in their marketing, since they so strongly hyped the modular aspect of the 21X3 controller & daughter boards.  I think the breakout board options can possibly be mixed & matched, but these driver boards cannot.

The 2183 board is still fine in its own right, it would just need external stepper or servo amplifiers to control.  I think I'll hang onto the extra 20640 card in the (hopefully) unlikely event it's needed as a spare.

So at this point servos & steppers are *theoretically* equally viable options since no additional amplifiers for them would be needed.  Now, whether they are financially viable is another question, not to mention whether the requisite down-gearing needed to get useful torque is something I have room for (physically or financially).  Servos would definitely be cool, but I've also seen impressive results using steppers with micro-step drives.


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## JimDawson

barnbwt said:


> I understand the significant commitment of resources needed to get one of these interfaces programmed & running; it just seems like Galil has limited itself by operating sole-source through Camsoft. It's not like they would sell fewer motion controls --new or used-- if they'd developed an in-house alternative that functions off of standard post-code like DC_CNC can. I suppose it just wouldn't be any cheaper than CamSoft, is all.



Many years ago I think they had a G code to DMC translator, but there are so many flavors of G code I can see that it would have been a monumental task to keep up with it, no two machines are exactly alike.  That's why there is a special post processor for each machine manufacturer, and many times different posts for different models within a product line.  The CNC machine market is a very small slice of the Galil total market and as far as I know there are no machine tool manufacturers that are using Galil products.  I have installed about 70 Galil controllers in various machines only 5 of which are CNC machine tools.  You'll find Galil products in everything from high speed factory automation machines, to medical systems, to missile tracking/targeting systems for the military.  They are very adaptable devices.


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## barnbwt

Ah, so they don't actually market to the CNC crowd at all, but generalized automation applications; that makes a little more sense, though it does seem like a missed opportunity (granted, for a competitive market).  You'd still think they would want to eventually base their interface around what is *today* a pretty standardized and stable machine programming language that many professionals are trained in.  But I can see that for most of their applications you wouldn't be swapping programs to the same degree as a CNC mill; just program a a single routine for the task manually through GalilTools and its set up for (potentially) years.  So the ease of programming aspect isn't as critical.


----------



## JimDawson

barnbwt said:


> You'd still think they would want to eventually base their interface around what is *today* a pretty standardized and stable machine programming language that many professionals are trained in.



If you are referencing G code here, that is only used in CNC machine tools.  G code is very limited in scope, and not very useful for most applications, but great for controlling a tool position.


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## Karl_T

Jim, you didn't start with that DMC translator for your project???

It was written in visual basic. source code popped right out of a decompiler.  DAMHIKT  camsoft is also largely written in visual basic but it has a large number of macros written in assembly language - those do not decompile.


Just another data point - Mach 4 tried to do Galil - they gave up. I was surprised here. I had thought the hobby crowd would have helped make this happen. But then Mach lost all its steam when the original author moved on.

I doubt Jim has plans to market his software to the general public. They would kill him with complaints. Getting a pc with HMI (human machine interface) and Galil card to make a machine with all sorts of hardware options  work correctly is over the ability of most people. AND then they complain to the vendor.


----------



## JimDawson

Karl_T said:


> Jim, you didn't start with that DMC translator for your project???



No, I wrote my own translator.  Easier that way, not locked into someone else's idea of the way the world should work.



> I doubt Jim has plans to market his software to the general public. They would kill him with complaints. Getting a pc with HMI (human machine interface) and Galil card to make a machine with all sorts of hardware options  work correctly is over the ability of most people. AND then they complain to the vendor.



You are correct.  That would make it a full time job and then some and there isn't enough money in it to make it worthwhile.  I would rather give it away to a select few and just have some fun and make a few friends.    I have sold software to the general public and I'll never do it again.  Industrial customers are hard enough to deal with, and they pay well.


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## Karl_T

You are a better man than I am. Every time I help, they either are not happy or ask for more. In other words, no good deed goes unpunished.


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## macardoso

Karl_T said:


> These are built solid as a brick sh*t house


 Love it!


----------



## barnbwt

So my controller showed up, and now I'm going to try to get it energized this weekend, and hopefully not myself in the process.  First order of business is a bunch of document research to double-check-re-verify that it runs on 24VDC the way I think it does.  Apparently the servo & stepper drive boards can be configured to share power with the main board so only one power connection is necessary, but at 48V rather than 24V.

Board looks really good, btw; even came with some expensive-looking tape connectors that combine all the Dsub encoder & i/o plugs back into a single unhelpful 50-pin bus plug (I think it's the same style used in the big Galil breakout panels, but I won't be using them).  Price was very good, so if the boards aren't toasted, I assume it's because the seller didn't quite know what he had (the daughter boards cover up most of the markings)

I've been looking back into motors, trying to remember what all was lost.  These guys look to be sized about right for use with a 3A, 48V driver (though mine goes up to 60V);
https://www.ebay.com/itm/NEMA23-381...2100-35-4B&_from=R40&rt=nc&_trksid=m570.l1313

I would be only running them to about 700rpm before their fall-off; this gets me minimum torque of 10.6 in-lbs per my calculations and their torque-chart.  That rpm would traverse the Z-axis in 5 seconds at a 1:1 ratio, and the X-axis in the same 5 seconds at a 3:2 ratio.  More phoney-baloney calculations suggest this would only apply around 300lbs in the Z axis; I'm not sure that's quite enough to be rigid, even on a machine this light.

So now I'm looking at servos, since they appear to generate about twice the torque at that rapid speed, and still a good 50% more even at low speeds.  Plus I know they're generally more efficient all around.  What I'm still unsure about are my options in the 200W 60V range, and exactly what types of servos I can run.  It seems like everyone is calling every kind of digitally-controlled motor a servo now, which isn't helping.

It looks like Animatics makes a line of NEMA23-sized 48V servo motors that seem like a logical (if not economical) choice.  Any other brands or product lines out there I should look into?


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## JimDawson

Exactly what Galil board did you get?


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## barnbwt

Tis a DMC-2183, with SDM-20640 and AMP-20440 daughter cards


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## macardoso

Here are my thoughts on the stepper/servo debate. 

Steppers remain king in the hobby world because they are cheap and easy to apply.  Their moderate speeds suit us hobbyists who will likely crash a machine moving 1000+ ipm (at least i would  ). 

However, servos are truly better in every aspect except for price.  And when I say servos, I am talking specifically about modern AC servo motors.  They maintain a fairly flat torque curve out to their rated speed and have a peak output of somewhere around 300% of the rates torque.  What this means for you is that you only need a servo that produces a rated torque of 1/2 or 1/3 of the size of stepper you would buy.   I would aim for the 200-400W range of servo for a mini mill to a bench top mill or lathe, and 750W for a machine the size of a tormach, however you can push that in either direction.  

There are DC fed drives for AC servos (Look at the DMM technology DYN2 drive) but a vast majority are fed from the AC line.  Expect single phase input up to 2kW and 3 phase input after that. I’ve used the DYN2 before and was quite happy with it.  Not too if the line, but the price can’t be beat. Remember you need a beefy DC supply to feed them at at least 60VDC.  

I personally would stay away from DC servos unless you want an electronics project. Closed loop steppers sound like a nice mid point but I’ve never tried them.  They cost nearly as much as a low end AC servo.


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## Karl_T

You most certainly want servos. Don't skimp on size. Jim bought from a really good servo vendor on his recent build.  I am a fan of DC servos on ebay - they go for a song if you watch a while. Then use AMC servo amps which also go for nothing.

You might consider more I/O with a DB 28040 card. An operator panel with lots of I/O really makes the machine


----------



## barnbwt

macardoso said:


> Here are my thoughts on the stepper/servo debate.
> 
> Steppers remain king in the hobby world because they are cheap and easy to apply.  Their moderate speeds suit us hobbyists who will likely crash a machine moving 1000+ ipm (at least i would  ).
> 
> However, servos are truly better in every aspect except for price.  And when I say servos, I am talking specifically about modern AC servo motors.  They maintain a fairly flat torque curve out to their rated speed and have a peak output of somewhere around 300% of the rates torque.  What this means for you is that you only need a servo that produces a rated torque of 1/2 or 1/3 of the size of stepper you would buy.   I would aim for the 200-400W range of servo for a mini mill to a bench top mill or lathe, and 750W for a machine the size of a tormach, however you can push that in either direction.
> 
> There are DC fed drives for AC servos (Look at the DMM technology DYN2 drive) but a vast majority are fed from the AC line.  Expect single phase input up to 2kW and 3 phase input after that. I’ve used the DYN2 before and was quite happy with it.  Not too if the line, but the price can’t be beat. Remember you need a beefy DC supply to feed them at at least 60VDC.
> 
> I personally would stay away from DC servos unless you want an electronics project. Closed loop steppers sound like a nice mid point but I’ve never tried them.  They cost nearly as much as a low end AC servo.



Agreed, servos are definitely the more optimum solution.  I maintain that if they were simply easier to deal with they'd be far more popular in this retrofit/diy/hobby field; the cost is honestly a tiny mole-hill compared with the trouble of implementation (and the difficulty in implementation makes the cost a far riskier gamble)

Well after some more research, it looks like my servo amplifier board (I'm not going to go down the rabbit hole of dealing with more external drives at this time) is feeding power to the motion controller, and since it appears my unit has the 24V-range voltage converter installed for that job, it means my servos are limited to 36V maximum* (@3.3A, therefore ~100W max output).  This board also only drives 2-conductor brushed motors.  So I think that puts the kibosh on going with servos for now; I'd have to invest in additional drivers & power supplies to run them, and that's beyond my scope for the moment.  Hopefully I learn enough from the servo spindle aspect to implement servos at some later date.  For now, I was simply looking into it since the amplifier board came 'free' which may have helped offset the cost of the servos.  It sounds like biigger, AC servos are what I'd want in any case.

*Now, if that shared-power supply feature can be disabled --and it perhaps can be by removing a jumper-- the servo board can be fed up to 60V, for the full 200W at 3.3A.  That's *barely* enough for it to be worthwhile from what I've seen, though I'd be limited to a rather limited and expensive selection of used motors (mostly Fanuc or similarly high-end)


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## JimDawson

So at least for now you are planning on using stepper motors with the onboard amps?


----------



## barnbwt

Karl_T said:


> You most certainly want servos. Don't skimp on size. Jim bought from a really good servo vendor on his recent build.  I am a fan of DC servos on ebay - they go for a song if you watch a while. Then use AMC servo amps which also go for nothing.
> 
> You might consider more I/O with a DB 28040 card. An operator panel with lots of I/O really makes the machine


Impressive, those used breakout boards are more expensive than the controller assembly, lol.  I'll keep an eye out, though; I agree that whichever --servo or stepper-- board I end up not using would be better replaced with an I/O panel.

I did find what *appears* to be a series of quality servo motors that fit the power & voltage envelope (assuming I can decouple the power supply of the servo board from the controller)
http://www.animatics.com/products/smartmotor
These run at 48V as best I can tell, and when geared down 10:1 or so for the rapid speeds I'm looking at the torque values are very powerful.  Now they're kind of a fully-integrated setup designed to be run by RS232 if I read correctly, but it does still appear to have the usual motor & encoder outputs to run it like a 'dumb' motor/encoder pair synched up by the driver board.


----------



## barnbwt

JimDawson said:


> So at least for now you are planning on using stepper motor with the onboard amps?


It's certainly the most clear-cut path.  I will do some more research on servos to see if I can pull them off at this time, but I suspect it won't be practical.  For sure I have to find out if that 24V pass through from the servo board to the controller can be disconnected without help from Galil (assuming they haven't already blocked my phone number, lol)

The path forward with servos would be;
1) Energizing the servo board with 48V without frying anything
2) A good deal on a used ~200W, 3A servo that can be geared down to about 30 in-lbs @ 500RPM (lets say <150$ per motor)
3) Nema23 interface and a <8" length envelope
4) The ability to tune this particular set of servos (I have no idea how realistic this is for the Galil driver board)

The path for steppers is;
1) Figure out how much slower my rapids have to be to swing a 60V stepper @ 3A (though it's not like rapids have to be 'rigid' in practice)
2) Find a Chinese stepper variant that matches these specs & buy one from one of a jillion identical vendors


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## JimDawson

All of the newer boards can have isolation option for the drives, and in reading through the documentation for the AMP-20440 documentation it looks like the motor power is isolated from the board power by default.  The board requires separate power from what I can see.


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## JimDawson

I think your better options might be to: 1) save your nickels & dimes until you can afford at least 400W AC servos & drives (about 300/set), or 2) to get running for now, buy some cheap NEMA 34 steppers & drives (about 90/set).  You would need 60V power supplies in either case.

I read back through the thread and maybe I missed what you are going to use for a spindle motor.


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## barnbwt

The spindle is a just over 1kW @ 4000RPM Baldor, driven off a 10A Parker amplifier.  Is 400W per axis really needed for a 1" swing lathe slide?  A friend has 570oz-in NEMA23 steppers moving his 100lb mill table around against a 3hp spindle; I figure this shouldn't be anywhere near as demanding as that (40lb table, 1.3HP spindle).  My goal is also keeping the power consumption well below 20A @ 110VAC, which I'm aware is rather limiting.  The machine needs to be 'oven' sized, not refrigerator sized, too.

I would like to stick with NEMA23 form factor for steppers if possible, and 381oz-in appears to be about as good as I can get through my amp board for that size.  It appears NEMA34 gets me to 465oz-in, but with faster fall-off.  Part of the issue, which has been an issue since the start, is knowing how much holding force my tools actually need for this task, since that is what actually drives the motor sizing.  I believe I ended up with 400lbs minimum motive force being my goal through some questionable calculations last year.  Feel free to weigh in on whether that seems realistic or not.

May I request a quick sanity check from someone here?  Is 3A at 48V yielding 381oz-in correct, or are the spec sheets giving parallel-wired torque figures and series-wired current draw?  There's a lot of misleading or outright incorrect information in many listings

Second sanity check would be servos delivering just over double the torque of a same voltage/amperage stepper at their operating speed (a little over half way to max rated in both cases).  As I see it, servos have 1/3 the torque, but run over 6 times faster.
My references are;
http://www.animatics.com/products/smartmotor/sm23305d  (being run at a 1/3 lower-than-rated amperage of 3.3A, 40Oz-in @ 4500rpm)
Stepper Motor (being run at a 1/7 lower-than-rated amperage of 3A, 120Oz-in @ 700rpm)

Those servos appear to gin up about as much torque as my buddy's 5A 570oz-in steppers, even at a lower-than-rated amperage (assuming linear torque response).  But with much less juice, less heat, and presumably much smoother operation.  Once again interested in making servos work (darnit)


----------



## JimDawson

I'm running my mill 750W servos on a 120V, 20A circuit and have never had a problem.  Actually that circuit is running the lighting in that area, the mill controls (two 750W servos, one 1200 oz/in stepper, NEMA 23 stepper for the 4th axis, and the computer), my various grinders, the lathe computer, and anything else I may plug into that system.  No problems so far.  Most of the time the various motors are using a small fraction of their rated power, so the power system does not have to be sized as if everything was running at 100% power at all times.

Given the small mass that you need to move, NEMA 23 steppers will probably work fine.  Worst case using the NEMA 23 motors is that you lose some rapid speed and you have to keep the acceleration down to a reasonable level, they should have plenty of power at normal cutting speeds.  Unless you are trying to maximize production, who cares if it takes an extra second or so to move the next tool into position.  If power does become a problem, then gearing down 1.5:1 might be an option.  The problem is that when using steppers that may be a bit underpowered it is possible to lose steps without encoder feedback.  The good news is that encoder feedback can be added at any time, and is not required to get you up and running.  It needs to be noted that without encoder feedback, the DRO display will only be able to read where the tool should be rather than where it actually is.  So if steps are lost, the DRO will not reflect that.

My theory on steppers is to run them in the lower RPM range to keep them in the higher torque band.  This means high lead leadscrews, 0.250 or even 0.500 lead.  The leads on my router screws were 25 and 40 mm for the X & Y axes using 1200 oz/in NEMA 34 steppers, moving loads in the 700 lb range and capable of 600 IPM rapids.

I think you will be OK to start, and you can upgrade the system later if needed.


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## barnbwt

The plan was to add some el cheapo magnetic scales fairly early once the steppers were running open-loop, to at least mitigate issues with any step skipping.  I already have ballscrews (5mm Z pitch and 4mm X) but peak rapid speed isn't really a critical factor here.  The X moves only 6" and the Z 12".  It would be 'nice' for the machine to run to limits in only five seconds, but so long as I can cut fast thread pitches at proper surface speeds without losing steps I'm a happy man.

Those Animatics servos are a pretty cool architecture, kinda wish I'd known about them before diving in since it's an interesting alternative to a centralized motion controller.  From what I gather, a computer generating motion commands instructs the servos, which each contain their own controller, driver, motor, and encoder, so the first control loop never leaves the motor housing.  At that point, the only additional feedback needed are limit/home switches to the relevant motors, and scale outputs to go back to the controlling machine.  All done via RS232 which is apparently scalable to over 100 coordinated axes, lol.  The onboard brains are apparently smart enough to run their own stored programs, even while being sent external data (macros called up by the controller program data, or pre-planned moves in response to I/O conditions).  I believe the RS232 is also what keeps them all synced up with each other in real time?  Very decentralized approach to automation, doesn't even need a central 'brain' really.

I'm not sure they're useful for my particular needs, since I've already got the driver & controller parts handled by the Galil & it'd just be redundant and potentially incompatible.  If I could find a standalone servo (motor/encoder only) with the same motor specs I think that might work really nicely.


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## JimDawson

I think you still have to have a motion controller connected to the Animatics motors.  Normally the communication protocol would be DeviceNET or CANOpen, and there are also Ethernet motion controllers.  Something like this http://www.galilmc.com/motion-controllers/multi-axis/dmc-52xx0

Rockwell Automation, Rexroth, and many others make controllers that use the CAN protocols
https://en.wikipedia.org/wiki/CAN_bus
https://en.wikipedia.org/wiki/DeviceNet

It might be possible to write your own motion control software using the CAN protocols and maybe even get it to run on a Windows computer, but it really requires a real time dedicated operating system to do this properly, and would require a lot of development time to really produce anything useful.  Not something I would want to tackle   I'll stick to the high level languages.  The thought of coordinating 8 axes makes my head hurt.   That's why they invented motion controllers, just tell it what you want it to do and let the controller figure out how to do it.

One system that perhaps you haven't looked at is the ClearPath motors.  They are a self contained servo and are relatively inexpensive.  But still require a motion controller.  https://www.teknic.com/products/cle...ervo-motors/clearpath-sd-stepper-replacement/


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## Karl_T

My two cents here. You got a Ferrari control and you are planning to use it to drive a Hyundai. You should either go steppers with Mach, or get quality servos.

A bit of history. When my Bandit control died in '95, I went to the only PC control available at that time (AHHA). had to go from servos to steppers. Started ruining parts due to lost steps. Went to huge steppers at high cost, still had trouble. Then I re-upgraded back to the servos just like what I took off - problems solved.

IMHO, the only reason for steppers is to build a low cost machine. Steppers with mach cost maybe 10% of my servos with camsoft control.


<EDIT>

Just one option here. Like I said I like DC servos => lots of bang/buck

30 seconds of shopping found this servo: (you can do better - get all servos the same)
https://www.ebay.com/itm/Dynetic-Sy...m=112955618697&_trksid=p2047675.c100005.m1851

An AMC drive will cost less than $50.

You'll need an encoder - US digital has them for about $75 each. Or go real top end with linear strips. many servo offers include the encoder.

You need a DC power supply  - one for the whole system.

If you decide to go this route, I can hold your hand. I don't think its terribly difficult.


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## barnbwt

JimDawson said:


> I think you still have to have a motion controller connected to the Animatics motors.  Normally the communication protocol would be DeviceNET or CANOpen, and there are also Ethernet motion controllers.  Something like this http://www.galilmc.com/motion-controllers/multi-axis/dmc-52xx0
> 
> Rockwell Automation, Rexroth, and many others make controllers that use the CAN protocols
> https://en.wikipedia.org/wiki/CAN_bus
> https://en.wikipedia.org/wiki/DeviceNet
> 
> It might be possible to write your own motion control software using the CAN protocols and maybe even get it to run on a Windows computer, but it really requires a real time dedicated operating system to do this properly, and would require a lot of development time to really produce anything useful.  Not something I would want to tackle   I'll stick to the high level languages.  The thought of coordinating 8 axes makes my head hurt.   That's why they invented motion controllers, just tell it what you want it to do and let the controller figure out how to do it.
> 
> One system that perhaps you haven't looked at is the ClearPath motors.  They are a self contained servo and are relatively inexpensive.  But still require a motion controller.  https://www.teknic.com/products/cle...ervo-motors/clearpath-sd-stepper-replacement/


I'll make one last attempt & ask the Aminatics folks if the brains can be bypassed, and run like a motor/encoder pair.  There's a pair on Ebay that look really good for this application.  Those Clearpaths look nice as well.  In either case I'd have to bypass the servo (or stepper) amp boards and run them directly off my controller & an external amplifier since they are brushless.


Karl_T said:


> My two cents here. You got a Ferrari control and you are planning to use it to drive a Hyundai. You should either go steppers with Mach, or get quality servos.
> 
> A bit of history. When my Bandit control died in '95, I went to the only PC control available at that time (AHHA). had to go from servos to steppers. Started ruining parts due to lost steps. Went to huge steppers at high cost, still had trouble. Then I re-upgraded back to the servos just like what I took off - problems solved.
> 
> IMHO, the only reason for steppers is to build a low cost machine. Steppers with mach cost maybe 10% of my servos with camsoft control.
> 
> 
> <EDIT>
> 
> Just one option here. Like I said I like DC servos => lots of bang/buck
> 
> 30 seconds of shopping found this servo: (you can do better - get all servos the same)
> https://www.ebay.com/itm/Dynetic-Systems-D-C-Servo-Motor-230091/112955618697?_trkparms=aid=222007&algo=SIM.MBE&ao=2&asc=53210&meid=1293ba83eed64c169a584bc9970a9deb&pid=100005&rk=1&rkt=3&sd=141869370410&itm=112955618697&_trksid=p2047675.c100005.m1851
> 
> An AMC drive will cost less than $50.
> 
> You'll need an encoder - US digital has them for about $75 each. Or go real top end with linear strips. many servo offers include the encoder.
> 
> You need a DC power supply  - one for the whole system.
> 
> If you decide to go this route, I can hold your hand. I don't think its terribly difficult.


I was looking at those motors, actually. My board controller only does brush motors, which are much rarer for servos as I can tell.  So I'd just need motors & encoders (and a 60V power supply to get the most power from them).


----------



## JimDawson

barnbwt said:


> Those Clearpaths look nice as well. In either case I'd have to bypass the servo (or stepper) amp boards and run them directly off my controller & an external amplifier since they are brushless.



The ClearPath motors have the amp built in to the motor.  You only need to supply power and a step & direction signal.  The downside is that there is no provision for encoder feedback directly from the motor, for feedback an external encoder would need to be used.

The Animatics also have the amps built in, so you would need to supply power and the control seems to be some derivative of CAN or EtherCat


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## barnbwt

Man, Clearpath has some cool videos of their stuff.  I always thought servos were annoyingly whiny; those things are dead silent, especially with their acceleration damping algorithm.  I think it'd be like $700 for a two-axis system using those things, but that actually seems like a good deal for what you get.  I still need to look into their service life/reliability to convince myself.  Those things along with a linear-encoder on the axis giving feeedback to the controller should be a pretty well-regulated system, right?

In the coming days I'm also going to work on migrating my NX-based CAD models of the machine over to Fusion.  We'll see just how limited that program is when assemblies start getting a little complex.  Hopefully I'll have some ideas for improvements along the way as well.


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## JimDawson

Servos are normally very quiet, steppers are annoyingly whiny, especially those drives without resonance damping.

I can't address the service life of the ClearPath units except to say that I installed a set of the 750W units on a router retrofit a year or so ago for a customer and they are still running fine.  I installed one 20 AMP, 70V power supply to run all 4 motors.

The loop is closed at the servo so no additional feedback is really required, as long as your lead screws have near zero backlash, the system should be fine without linear encoders.  Because of the way they work, you really can't lose steps.

If you haven't already looked at the DMM servos, they might be worth a look also, I'm using their 1.8KW servos on my lathe axis drives.  https://store.dmm-tech.com/


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## macardoso

barnbwt said:


> Those Animatics servos are a pretty cool architecture, kinda wish I'd known about them before diving in since it's an interesting alternative to a centralized motion controller. From what I gather, a computer generating motion commands instructs the servos, which each contain their own controller, driver, motor, and encoder, so the first control loop never leaves the motor housing.



This is actually the way that most control architectures for servos work nowadays.  Not necessarily the motor + drive in one package, but the distributed control over a network.  It began back in the day by sending commands over Modbus, ControlNet, Devicenet, CAN, etc. where a single network cable drop could save thousands of feet of I/O cables.  This allowed the processor to be placed in a central location, with drives located near their motors.  Modern controls take advantage of the high speed networks we have today like Ethernet/IP, EtherCAT, Profinet
, and a few others.  For us as hobbyists, they are significantly less useful because we don't have a way to interface with this network easily.


----------



## macardoso

barnbwt said:


> I'll make one last attempt & ask the Aminatics folks if the brains can be bypassed, and run like a motor/encoder pair. There's a pair on Ebay that look really good for this application. Those Clearpaths look nice as well. In either case I'd have to bypass the servo (or stepper) amp boards and run them directly off my controller & an external amplifier since they are brushless.



My recommendation would be to stick with the motor and drive combo that the servo manufacturer recommends.  Trying to mix and match servos (especially AC brushless) can really get you into a mess.


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## barnbwt

It must be old-school brushed DC servos I'm thinking of then.  You'd hear a whistle every time they'd spool up to 8000rpm (think movie-style robot noises).

I've decided I need to review my basic design criteria before making a decision on motors.  According to a Kennametal calculator, it appears that for my ~1" diameter envelope, both steel & speed aluminum turning would impart about 50lbs of tangential cutting force, and about 20 axial (along the bar).  Now that's just the max cutting forces; is there a rule-of-thumb for how much more powerful the ballscrews' holding force needs to be for solid control of the cut?  At only 60lbs and lathe-speeds, I'm certain the moving mass of the slide isn't the driving factor for the axis motors like it is for big mill tables & routers.


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## JimDawson

barnbwt said:


> Now that's just the max cutting forces; is there a rule-of-thumb for how much more powerful the ballscrews' holding force needs to be for solid control of the cut? At only 60lbs and lathe-speeds, I'm certain the moving mass of the slide isn't the driving factor for the axis motors like it is for big mill tables & routers.



I'm sure there is a rule of thumb that real machine tool engineers use, but I have no idea what it might be.  A guess would be about 3X.  Normally I look at what others have done to have an idea of what works.  When in doubt go bigger, you can always easily torque limit any motor you decide to use, but it's really hard to get more power out of a under powered system.

I think you're correct, at about 60 lbs, the moving mass is probably not a factor.


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## Karl_T

Let the pros do the design work. Just copy what they did. Your machine is most similar to a hardinge CHNC or a Omniturn gang lathe. they both have 1/4 hp. servos. that's about 200 watt.


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## barnbwt

Karl_T said:


> Let the pros do the design work. Just copy what they did. Your machine is most similar to a hardinge CHNC or a Omniturn gang lathe. they both have 1/4 hp. servos. that's about 200 watt.


LOL, fair enough; that's how the pros designed their stuff in the first place, after all (copying others' successful parameters) 

FWIW, the 'ideal' formulas for cutting force suggest ~50W is needed to control the cut, so 200W would be a safety factor of 4; that's pretty rigid, which is what I want, here.


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## macardoso

Something to think about.   Power is a function of torque and speed. Your rigidity is purely dependent on torque. Make sure your holding torque is sufficient.  A 200W servo rated at 2000 rpm will have more continuous torque than a 200W servo rated at 5000rpm.


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## barnbwt

macardoso said:


> Something to think about.   Power is a function of torque and speed. Your rigidity is purely dependent on torque. Make sure your holding torque is sufficient.  A 200W servo rated at 2000 rpm will have more continuous torque than a 200W servo rated at 5000rpm.


Yes, but the higher-speed servo will (need to) be geared down for my desired rapid speeds (about 700rpm IIRC), and per some comparisons, they end up a lot closer to parity (because both are so efficient).  The faster motor can react more quickly, but I think that aspect is damped out by the presence of the belt/geartrain vs. a direct drive arrangement with the stronger motor.

It seems Tamagawa Seiki has a line of 48V DC brushed servo/encoders in this power range that are around on the used market, sometimes for reasonable prices.  That seems about right for the 200W supply, though it'd be nicer if the voltage were closer to the driver's capacity of 60V.

I'm not sure what motors this Galil driver board was designed for; 60V @ 3.3A (200W) DC brushed doesn't seem very common at all (48V, 60V, and 100V versions are far more common, across multiple manufacturers).  Perhaps they were not really intended to operate right at max (volts or amps) and are commonly paired with 48V & 60V motors, with some headroom.


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## Karl_T

Galil will run any servo that takes a 0 - 10 volt signal.

I play fast and loose with the volt ratings. No way will the insulation break down if you go 20 volt higher. They just don't want the extreme RPM the motor would spin up to at the higher voltage. That never happens under servo control anyway. This may shock some of the more conservative in the crowd.


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## Karl_T

Galil will run any servo that takes a 0 - 10 volt signal.

I play fast and loose with the volt ratings. No way will the insulation break down if you go 20 volt higher. They just don't want the extreme RPM the motor would spin up to at the higher voltage. That never happens under servo control anyway. This may shock some of the more conservative in the crowd.

why this is late:
https://www.hobby-machinist.com/threads/message-awaiting-moderator-approval.72040/#post-604425


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## barnbwt

Karl_T said:


> Galil will run any servo that takes a 0 - 10 volt signal.
> 
> I play fast and loose with the volt ratings. No way will the insulation break down if you go 20 volt higher. They just don't want the extreme RPM the motor would spin up to at the higher voltage. That never happens under servo control anyway. This may shock some of the more conservative in the crowd.
> 
> why this is late:
> https://www.hobby-machinist.com/threads/message-awaiting-moderator-approval.72040/#post-604425



Okay, increasing the voltage (within reason) makes sense; but how would one drive a 48V servo at 60V without creating an overcurrent condition --something the motors most definitely cannot tolerate?  As I see it, I could get a 48V servo which runs at 2.5A, and drive it at 60V to draw ~3.1A.  This puts me closer to my 200W target zone of 60V @ 3.3A, but the 25% extra current seems like it could be an issue for heat generation.

Or is the effective (not instantaneous) current limited by PWM duty-cycle, so the same 2.5A are drawn despite the 48V peak voltage during the shorter pulses?


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## Karl_T

Yep, you're not within specs. don't expect any warranty. I'm just sayin' I've done it.

Keep in mind I don't push my machine to max speeds and feeds so the duty cycle exceeding specs is minimal.


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## barnbwt

Okay, I think I found a possible brushed, DC, motor/encoder pair (it seems like these aren't wedded/integrated as often in DC servo applications for whatever reason, the way BLDC motors are; I'm guessing since the BLDC needs the encoders for its commutation, whereas the brushes do all that mechanically?)

Reliance Electro-Craft E243 Series (this example is broken, but they are a common motor on ebay)
It appears these are legacy products that have gone through several name changes (E or G, 240 or 540).  But the specs I see from several different old catalogs appear the same (same peak/cont torque, same current draw, RPMs were derated to 5000krpm from 6000krpm at some point)

60VDC Max operating voltage --Check
4A, 3.1A, 2.3A cont. current --Check (this is for the A, B, and C winding, I think.  The linked motor appears to be the 'A' winding; I'm limited to 3.3A)
5000-6000RPM max speed --6-7:1 ratio
55oz-in cont. torque --330-385oz-in, this seems possible a little low; my rapids may need to drop some more
Many of these are fitted with an HP HEDS-5000 type encoder (not much info on the various options, however it does appear at least some are 1000ppr, likely depending on vintage)
Many of these look to be in the sub-100$ range which is also attractive; not that different from the steppers in that they plug directly to my board amps

I *think* those parameters all fall within the specs of my on-board servo amplifiers, if I am understanding them correctly


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## barnbwt

Karl_T said:


> Yep, you're not within specs. don't expect any warranty. I'm just sayin' I've done it.
> 
> Keep in mind I don't push my machine to max speeds and feeds so the duty cycle exceeding specs is minimal.


Yeah, I have been somewhat counting on the fact this machine is a lathe (vs. mill) helping me out in that department.  Not very often you'd be rapiding fully across a 6"x6" space, both axes at the same time, against a load.  Usually you'd have one axis doing all the work, the other moving slowly or holding position.  And seeing how the cutting is 'automated,' I can afford to do things more slowly so long as they are consistent.

Honestly, the only time anything should see its limits pushed to an extent, would be the spindle turning as fast as it can when cutting aluminum (since it has such high surface speeds).  Even then a shallow cut will be the most common action.


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## Karl_T

I use the E690 series of that exact motor on my mill.

It is rated 60v max. I use a 2:1 step down transformer through a bridge rectifier and then an electrolytic capacitor for a very cheap effective power supply that gives about 70 volts. I got the transformer and capacitor free, paid about 50 cents for the rectifier.  Just google for dc power supply and plans for these pop right up. If you care a power transistor can easily be added to limit the voltage. I *WAS* going to do this but did not have one the weekend all the parts went together. Ran it without and nothing got even close to hot so I've never got around to adding this..

There are AMC brand servo amps on eBay for these servos that go for peanuts.

This combination works great with galil.


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## Karl_T

just for grins I surfed for an AMC servo amp. here's a new one:
https://www.ebay.com/itm/Advanced-M...ols")+Servo+&_from=R40&rt=nc&LH_TitleDesc=0|0

does up to 12 amps and 80 volts. Being the extremely frugal type (cheap a$$ in other words) , I watched for these and never paid $20 each


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## barnbwt

Well, we'll see if these Electrocraft E243 motors work out.  Going by torque charts at 4000rpm, it looks like I'll have around 700lbs holding force on Z, 950lbs on X, at about an 8:1 gear ratio for both (still within belt range so I can avoid gearboxes, though they do exist).  I also found a nice 60V switching power supply good up to 8A that should be overkill in practice.

Dialing back my rapid speed 'requirement' from five to seven seconds traverse on Z makes things much more reasonable as far as the 200W-class motors are concerned.   Direct-drive is nice in theory because of the simplicity, but now I think I can use a belt connection to tuck the X-axis servo beneath the apron for a very clean and protected result, so that's a net improvement.

I'm still debating whether to go with a quick-change toolpost arrangment with one tool block at the lower/left corner of the top slide, or a gang arrangement.  The former gives better modularity but is more labor intensive without a tool changer (one day...) the latter is simpler to implement but slightly more work to program for.  Both put the center of the slide at a slightly different spot relative to the spindle axis.  Any slant-bed users care to weigh in on which they prefer?  Since I work around Swiss lathes all day, I keep getting weird ideas for how to arrange the tool mounts, but simplicity is probably next to godliness for this project.


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## JimDawson

My preference is a turret.  But that would be a lot of work to implement in this case and add a lot of moving mass to the system.  The next choice would be a gang tool setup.  Not really difficult to program, just assign each station a tool number and and let the software take care of the offsets.  In the software, the X & Z positions are set to some position, normally referenced to the X and Z home as machine coordinates.  In my software both the machine and part coordinate offsets is set with a mouse click. Then that offset is applied to each tool when called.  X is always relative to the spindle C/L where the tool point on C/L = X 0.0000

BTW, I don't like switching power supplies for motor power.  If you don't want to build one, then something like these would be my choice.  https://www.automationtechnologiesinc.com/products-page/torroidal-power-supplies/


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## Karl_T

I'd go gang IF you can install a long X axis. Simple and really fast to switch tools.

OTOH, I have a turret with a change plate. As long as the plate is assembled, can go back to that part in just a few minutes. Big time saver.


BTW, I've seen reports of issues with switching power supplies. No first hand knowledge.


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## barnbwt

Maybe a swappable gang plate would be a compromise?  I read that regulated power supplies have a harder time handling back EMF, but as small as these motors are I can't imagine that's a huge issue here.


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## Karl_T

Totally unrelated but EMF noise can/will drive you nucking futs.

My lathe X axis would go unstable on occasion. Chased it for hours and hours. I ended up going to differential encoders to solve it but the root cause was EMF noise.

Two lessons learned:
1) be serious about electrical noise sources and grounding
2) never cheap out on single ended encoders


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## barnbwt

Exciting developments (I guess);
I got confirmation the 18-36V (or 36-72V) input range of my main board voltage converters does NOT also apply to the 18-60V range of the motor-power circuits on the daughter boards.  Makes sense in retrospect, but their manual does not imply they are independent.  So I can use motors to the full 200W level, and my gimpy "24V" (19.8V measured) power supply should still be sufficient at least for testing.

My confusion had stemmed from not realizing there are two levels of amplification here, not one.  The 5V source logic circuit regulates the analog and 'line level' (for lack of a better term) digital outputs from the main board, which are supplied by the 12V source.  The 12V outputs in turn regulate the 18-60V motor current source on the daughterboard to spin the rotors.

So the sub boards are run directly by those 12V outputs and 5V bus voltage through their connection to the main board, hence there only being external connections for motor power.  The converters on the main board let you deliver the 5V and 12V through a single connector at 18-24V (and presumably cleaner power going into the logic circuits).  Very convenient.

At 60V is interference really such a certainty?  Friends have had stepper motor issues running at 24V that vanished when raised to 48V since the signal was essentially stronger (that was my understanding at least)

This 60V Absopulse is supposed to be a fairly nice industrial power supply so you'd think EM emissions would be minimal, and the power output in the wires pretty clean.


----------



## JimDawson

barnbwt said:


> Friends have had stepper motor issues running at 24V that vanished when raised to 48V since the signal was essentially stronger (that was my understanding at least)



Regarding steppers, at 24V they were way under driving the steppers.  The best way is to max out the voltage to whatever the driver is rated at.

In the case of brushed DC servos, you can run them at lower voltage and still get good performance.  On my mill, the motors are rated at 140VDC and I run them at 70VDC.  They won't reach rated max RPM, but I don't need 600 IPM rapids, and they have plenty of torque for anything that I am doing.


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## barnbwt

My target is 100IPM, though 

Now, Galil does make a BLDC driver board with 600W per axis (there's a cheap 4-axis unit on ebay) which would be great for a slightly more powerful rig.  Maybe next time.

Assuming my axis motors & encoders are in good shape, I think things may fall into place nicely.  I suppose limit switches are next on the list; are there any downsides to the capacitive types versus the mechanical ones?


----------



## JimDawson

barnbwt said:


> I suppose limit switches are next on the list; are there any downsides to the capacitive types versus the mechanical ones?



Inductive prox or mechanical is good.  I kind of lean towards slow acting mechanical, much more accurate and repeatable than snap acting.


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## barnbwt

Slow acting, so it's like a small-travel rheostat or something that crosses a pre-programmed electrical threshold?


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## JimDawson

No, it's just a contact closure, but it doesn't snap over like a regular switch.  In other words, it doesn't go ''click''  

here is an example https://www.automationdirect.com/ad...tal_Plunger_with_Roller_Actuator/AEM2G14X11-3


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## barnbwt

Oh; I'd seen those type, but just figured they were beefier coolant proof versions of the cheap micro button/lever switches.


----------



## Boswell

JimDawson said:


> Inductive prox or mechanical is good. I kind of lean towards slow acting mechanical, much more accurate and repeatable than snap acting.



Jim, that is interesting. Intuitively I would have expected the Inductive Proximity type to be the most repeatable and of course with no moving parts, I would also expect them to be more reliable.


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## barnbwt

Boswell said:


> Jim, that is interesting. Intuitively I would have expected the Inductive Proximity type to be the most repeatable and of course with no moving parts, I would also expect them to be more reliable.


I can see chips, fluid, and just grime messing with inductive/capacitive types, I guess.  Do temperature/humidity impact their readings as well (beyond thermal expansion)?


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## Karl_T

I've got the inductive proxes on both my CNC lathes, never had a failure. got the mechanical on my CNC mill. Did have one of them fail. Pretty small sample size though.

FWIW, this is something I'd shop for on eBay and buy spares. you need three per axis so the cost adds up. I like to wire them at 24 volt NC. That way a wiring failure causes a machine stop and 24 volt is just more robust for machine logic wiring.


----------



## JimDawson

Boswell said:


> Jim, that is interesting. Intuitively I would have expected the Inductive Proximity type to be the most repeatable and of course with no moving parts, I would also expect them to be more reliable.



They are pretty reliable, but more difficult to wire in depending on the application.  They come in 4 flavors as far as the wiring goes NPN NC, NPN NO, PNP NC, and PNP NO so you have to make sure you are getting the correct device for the application and the other hardware that you are using.  The limit switches have both NO and NC contacts and are compatible with all hardware.



barnbwt said:


> I can see chips, fluid, and just grime messing with inductive/capacitive types, I guess.  Do temperature/humidity impact their readings as well (beyond thermal expansion)?



Chips can be a problem depending on the sensitivity, and coolant could affect the capacitive devices.  Normally they are rated at IP67.  Temperature (within their operating range) and humidity do not affect inductive sensors but humidity could affect a capacitive device.  I have never seen a capacitive device used in any machine tool application, they are normally used in applications where something other than metal needs to be sensed, wood for instance.


----------



## Karl_T

Jim is there any application difference between PNP and NPN. I've never worried about it.

Now with a bit of work I probably come up with the Laplace transform describing the electron's potential across the NP junction


----------



## JimDawson

It depends on what you are connecting it to and what the other related hardware looks like.  Depending on the Galil model, it will take a NPN or PNP input, or NPN only.  The issue is the common to the inputs.  LS COM is separate from IN COM so can take different input types.  The real problem come in where you should be wiring travel and home limits as NC.  That way a wire break or other failure looks like a limit trip, and this is what you want.  It's just simpler with mechanical limit switches IMHO.  But I'm lazy


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## barnbwt

My motors arrived, hopefully I'll be able to jog them in the near future, but they look pretty good so far.  I'll have to do some research to determine EXACTLY what winding they have, but it'll be 3-4A at 60VDC for around 5000rpm, and 190-210W --every winding for this series-type falls near this regime. 

Three came with circular mounting adapters, slotted for belts to pass through, and 1"/25mm timing belt pulleys.   

Three of them have brakes (presumably 12VDC) which I may or may not remove depending on the current requirements.  Surprisingly, the brakes are not rigid like I'd expected, and the motor still has about 3 degrees of movement.  The one motor with no brake feels nice and smooth/tight in the bearings, just as you'd expect for a PMDC motor.

Three of the motors have Japanese Daido encoders on them (by their blue colors, I'd originally thought they were Tamagawa Seiki's).  I still haven't found the exact datasheet with the part number construction for this older series, but they appear to be 2500C/T incremental encoders, with an 8-wire pin-out helpfully provided on the label;

V/gnd, A +/-
B+/-
Z +/- which I presume is an index-pulse channel)
Two wires per channel which I believe makes them double-ended.  The current Daido H48 series use a 5V supply and are good up to 6000rpm

Now, two of the encoders have hairline cracks on the plastic cases; I'm not sure how significant this is in reality since I know ABS plastic moldings tend to do that anyway as they age.  The motors are very clean and the power wires covered with loose shrink-tube, so I don't think they were getting soaked in coolant or anything like that.

I did also want to mention that these motors were a bit larger than I was expecting (in length).  I guess BLDCs are a little more energy-dense since comparable units were around 5" in length, these PMDC motors are about 7" before the encoder is stacked on.  I'll find a way to fit them, but folks considering these should know they won't be getting a stepper-sized package like a BLDC provides, but something about 1/3 larger.


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## JimDawson

Yup, differential output on the encoders.  That is the only way to fly.  Yes, the Z is the index pulse.  

The only place you might need a brake is on the X axis, mine will drift down without it when not powered.


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## barnbwt

Karl_T said:


> Jim is there any application difference between PNP and NPN. I've never worried about it.
> 
> Now with a bit of work I probably come up with the Laplace transform describing the electron's potential across the NP junction


That sounds noise sensitive, to put it lightly 

I see plunger type and pivot-type limit switches (the big industrial ones).  Do the arms give more resolution/accuracy, or is it purely to make adjustment a bit easier once they are installed?  Lastly, once you're looking at industrial switches (sealed, large enough for a good bit of voltage & current) is there much of a difference as far as accuracy or longevity going with a Chinese product, vs a Honeywell or Allen Bradley?  I am mostly thinking of the durability of the contacts as 12V sparks across them a bunch of times.

Hmm, I probably need to start sketching out how the E-stop will be implemented; I've seen a number of home builds where this was half-assed, and "feed hold" was essentially the kill switch.  With steppers I'd be less concerned about crazy runaways, but I know that's what servos love to do when an encoder dies/etc so I'd like to do this one up correctly.


----------



## barnbwt

JimDawson said:


> Yup, differential output on the encoders.  That is the only way to fly.  Yes, the Z is the index pulse.
> 
> The only place you might need a brake is on the X axis, mine will drift down without it when not powered.


Yeah, I'm thinking that, too (would also be nice even on Z as a safety mechanism though).

Not to drift my own thread too terribly much, but I am considering a much more upright slant configuration (60deg vs 45) and the brake really would become a necessity.  My discussion about ganged-tooling earlier got me thinking; gangs don't work very well if you have a tailstock supported workpiece (unless I'm missing something) and my 7" max stickout would stand to benefit from that ability.  So how to get the tool gang around the workpiece so the desired tool can be selected?

If the headstock itself can move about 2-3" at an angle to the X-axis (across the table toward the operator in this case) the tool gang could slide freely behind the work piece without interference.  This would not be a controlled axis but a momentary shift similar to a powered draw-bar.  Combine that with a similarly 'dumb' tailstock center which can engage or disengage from the end of the workpiece a short distance.  It seems like it'd be a pretty fast way to change tools without adding a ton of complexity or volume (maybe some loss of rigidity?)  I'd be able to put right and left hand side tools at opposite corners of the gang positions and cut on the full 24" interior length between the spindle and the far wall.  Anyone try something like this before?


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## JimDawson

The arms make adjustment easier.  Normally for machine limits I use the roller plunger type and make a cam to operate them.

The slow acting switches are more repeatable than the snap acting ones.  The industrial switches come in both snap acting and slow acting.  Normally you are going to wire these directly to the inputs, so the current is a couple of milliamps, any contact should last in the millions of cycles.


----------



## barnbwt

I take it the Galil can be wired so one limit switch performs both Home and Limit duties?  That seems like a really slick way to get the job done on a few machines I've seen.

Honeywell's BZE6 series switch seems like a good fit here, and there's lots of them available online for reasonable prices (~15$)
https://sensing.honeywell.com/honey...v6-limit-switch-product-sheet-002383-2-en.pdf

Do the contact rollers introduce meaningful tolerance vs. a solid-stud plunger switch?  Roller has moving parts, but the solid hard stud would be affected by faster wear (either it or the contact surface)


----------



## barnbwt

Karl_T said:


> *You'll need an encoder - US digital has them for about $75 each. Or go real top end with linear strips. many servo offers include the encoder.*



I don't suppose you have any recommendations for linear encoders?  The AMS AS5311 seems to have some DIY usage (CNC Zone's been down all day so it's hard to answer the question) but I really need a primer on how these are set up, since they don't seem to be a turn-key product, but a component (the linear strip, AS5311 sensor, the board that it mounts to, and the interface with the controller are all separate)


----------



## JimDawson

barnbwt said:


> Yeah, I'm thinking that, too (would also be nice even on Z as a safety mechanism though).
> 
> Not to drift my own thread too terribly much, but I am considering a much more upright slant configuration (60deg vs 45) and the brake really would become a necessity.  My discussion about ganged-tooling earlier got me thinking; gangs don't work very well if you have a tailstock supported workpiece (unless I'm missing something) and my 7" max stickout would stand to benefit from that ability.  So how to get the tool gang around the workpiece so the desired tool can be selected?
> 
> If the headstock itself can move about 2-3" at an angle to the X-axis (across the table toward the operator in this case) the tool gang could slide freely behind the work piece without interference.  This would not be a controlled axis but a momentary shift similar to a powered draw-bar.  Combine that with a similarly 'dumb' tailstock center which can engage or disengage from the end of the workpiece a short distance.  It seems like it'd be a pretty fast way to change tools without adding a ton of complexity or volume (maybe some loss of rigidity?)  I'd be able to put right and left hand side tools at opposite corners of the gang positions and cut on the full 24" interior length between the spindle and the far wall.  Anyone try something like this before?



The only slant bed lathes with a tailstock that I have seen have a turret rather than gang tooling.  I could imagine a system that would retract the tailstock, change the gang position, then move the tailstock back into position or something like that.


----------



## JimDawson

barnbwt said:


> I take it the Galil can be wired so one limit switch performs both Home and Limit duties?  That seems like a really slick way to get the job done on a few machines I've seen.
> 
> Honeywell's BZE6 series switch seems like a good fit here, and there's lots of them available online for reasonable prices (~15$)
> https://sensing.honeywell.com/honey...v6-limit-switch-product-sheet-002383-2-en.pdf
> 
> Do the contact rollers introduce meaningful tolerance vs. a solid-stud plunger switch?  Roller has moving parts, but the solid hard stud would be affected by faster wear (either it or the contact surface)



Don't worry about tolerance, the limit switch is just to get you close.  The final home position is set with the Z pulse from the encoder.  I like the roller switches and a cam to actuate.



barnbwt said:


> I don't suppose you have any recommendations for linear encoders?  The AMS AS5311 seems to have some DIY usage (CNC Zone's been down all day so it's hard to answer the question) but I really need a primer on how these are set up, since they don't seem to be a turn-key product, but a component (the linear strip, AS5311 sensor, the board that it mounts to, and the interface with the controller are all separate)



You are planning on building your own linear encoder read heads?  That would be an ambitious project.   I use Ditron linear encoders, they wire right into the Galil.  Have a look at this thread where I installed a DRO on my manual lathe. https://www.hobby-machinist.com/threads/lathe-dro.58063/


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## JimDawson

barnbwt said:


> I take it the Galil can be wired so one limit switch performs both Home and Limit duties? That seems like a really slick way to get the job done on a few machines I've seen.



It is possible to do that with the latest generation cards by using the LD command.  There is also a workaround in software for the older cards using the CN command.


----------



## barnbwt

JimDawson said:


> Don't worry about tolerance, the limit switch is just to get you close.  The final home position is set with the Z pulse from the encoder.  I like the roller switches and a cam to actuate.
> 
> 
> 
> You are planning on building your own linear encoder read heads?  That would be an ambitious project.   I use Ditron linear encoders, they wire right into the Galil.  Have a look at this thread where I installed a DRO on my manual lathe. https://www.hobby-machinist.com/threads/lathe-dro.58063/


Ah, right; the index pulse; of course!

I wasn't hoping to have to build one, I just can't access any CNC Zone threads where people implemented that sort of linear encoder .  Most stuff I find is glass-scales which are usually a 'sealed unit' from what I understand (generally sold as a drop-in kit)

Also, after looking into the Ditron & Renishaw encoders, it really doesn't look like magnetic is any cheaper than glass (>100$/axis); just more easily trimmed to fit & a good bit smaller.  Also doesn't appear to be nearly as common.  I do notice there's a ton more Chinese glass scales for sale than I remember seeing, so I guess the Politburo has decided to target that industry for the moment & it's driving prices down.  I'll put scales on the back burner for the time being and focus on firming up the physical layout now that the bulk of the electrical architecture is decided.


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## barnbwt

If you know of Ditron still selling the reader & tape for ~150$ I'd love to know; the only 1um magnetic reader I can find from China is 250$/per and the tape 100$/m (about what I'd need).  Comparable accuracy glass scale assembliess are about 100$ per axis.


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## JimDawson

The glass not sealed tight, they do get dirty after a time.

Contact Jaeger at Ditron for a quote.  
sales@dcoee.com

Feel free to say I recommended him.


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## barnbwt

Here's a concept of the idea I mentioned earlier, about adding a true third axis to the lathe by moving the head stock.




If a 2-axis is a 'slant bed,' this would be a 'V bed.' Here are the high points;
1) I'm designing from the cut area outward, hence the floating parts
2) X axis is kicked up 60degrees, with about 3.5" of travel up and down from the position shown (it's the steep axis on the right in this view)
3) Y axis is therefore 30degrees above horizontal, the spindle & motor will move along this.  Motion is about 1.5" up/out, 4" down/in (more later)
3a) Servo motor points down & hangs between the axis rails
4) Z axis is a normal left/right orientation, with 12" of travel to the right from the position shown (more later)
4a) Servo motor at the same elevation as the upper/back Z rail, behind the spindle




Tool plate layout (opposite angle to the first view, spindle/motor/Y&Z axes hidden).  Like I said, I've been around Swiss lathes a lot lately, so the thing I have here is almost a hybrid of a gang-plate and a dog-leg;
1) Turning tools sit atop a post clamped into the tool plate.  Rather than the cut load trying to 'bend' the tool, it is trying to 'compress' the shank
1a) Tool shanks secured in a slot by a wedge-clamp (probably a standard Swiss format clamp)
1b) The 'post' presenting the tool will have a cutting edge on its top & bottom side, so a left-hand tool can be used if the spindle is reversed
1c) If possible, a symmetric insert laid orthogonal to the XZ plane will accomplish 1b, cutting on both exposed edges
1d) The tools are selected by raising the headstock, sliding the tool plate to another 'gap' between cutters, and dropping the workpiece back down
2) Drilling and boring tools are located below the stack of turning tools, held in ER16 collet holders bolted into the tool plate
2a) These tools are accessed by sliding the toolplate about 4" along Z, then dropping the headstock down near its limit of travel
2b) To make room for these tools' stick-out, the Y axis rails move with the headstock (the carriages are fixed)
2c) These tools are 3" below the C/L of the turning tools, so with proper caution objects as large as the spindle OD can be swung if needed
3) The headstock moves up .6" to clear the turning tools; as it moves another .6" upward it hits a frame-mounted parting blade near the collet
4) The four tool spots up top are; L/R 55deg roughing insert, L/R 36deg finishing insert, HSS round/square grooving, HSS L/R 60deg thread
5) The five ER16 parts are; spot drill, two twist drills, ID boring tool, ID threading tool

Things I like about the idea so far;
1) Drills can be as long as the spindle if needed (or bore 6" deep in a 6" part)
2) Very high density of tooling; I have 14 cutting edges shown, all available at all times (for 99% of operations I'm likely to need)
3) Possibility of small live air-tools in the ER16 holder spots (some day)
4) Possibility of a live air-tool in the 3/8" bar slots (though it would block a number of other tool positions)
5) Mirrored turning tools could be mounted at the right-side of the tool plate, for turning a larger area than allowed by the Z travel alone
6) Tool changes seem like they would be very fast; as fast as rapiding to any particular point on a mill
7) The X and Y support beams will form an X truss in the frame
8) Possbility of a tailstock since the workpiece goes right over the top of the toolplate
9) It's really easy to blank off the Y-axis stuff & have my 2-axis layout if I decide not to go 3-axis 

Things I don't like;
1) Very careful programming & sequencing would be needed for everything, since crash-points are everywhere (just like a Swiss)
2) Would need to grind custom insert holders & HSS tools for the turning positions since the orientation is unusual (roller-box tool bits are similar)
2a) I honestly don't know if that sort of tool/workpiece arrangement even works w/o rollers; usually tools are loaded on the side, not the end
3) The spindle is cantilevered off its supports when it drops down to align with the drilling tools (about 3 inches)
4) The headstock gets a little complicated compared to bolting a spindle cartridge to a thick plate on the frame
5) Moving headstock likely makes powered collet actuation more difficult
6) One more degree of backlash on a light weight machine to worry about (but mills get by, so maybe not a big issue in practice)
7) Wild guess that the moving head-stock end will make coolant & chip-guarding more difficult
8) No good spots to put the X-axis servo motor; an 8:1 in-line planetary might be the best route for this one axis
9) As modeled, it's about a foot from the door to the Y axis rails to the spindle C/L; this seems awkwardly deep for access
9a) Tool setting looks at least as tight & awkward as for Swiss lathes


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## JimDawson

You're making my head hurt.    But a very interesting concept.


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## barnbwt

JimDawson said:


> You're making my head hurt.    But a very interesting concept.


Yeah, mine too.  It took three days for me to get the concept worked out.

It's like the spawn of a slant bed and a Swiss lathe.  No guide bushing, but a tailstock


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## barnbwt

Hopefully this helps clarify things;





I did determine that the concept is very similar to an old-school horizontal knee mill.  Except the knee moves the spindle up/down, as opposed to the X-Y table, almost more like a surface grinder in that sense.  That makes me a bit hopeful the idea has legs (but maybe arthritic ones)

I think tool crashes could be avoided fairly simply/automatically; there's a 'safety plane' between the turning tools and the parting bit, so at the end of each turning op lift Y to the safe plane, at the end of each drill/bore retraction lift to the same safe plane as well.  Tool changes would require sending the spindle to the midpoint between tool positions (the 'safety plane' in the X direction) before engaging them into the stock along X (or along Y, depending how the tools are ground and how 'smart' the Y axis is).  I will have to do a LOT more research before I can determine whether/how those routines can be configured in the Galil so they are called up by the generic T(X) tool G codes.


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## Karl_T

You know, a taper 50 horizontal mill with power feed on all three axis can be had for scrap value. SUPER RIGID machine. Put a 2J head on one end of the table with a Z axis in the quill, change the spindle out to something like a D1-3, add ballscrews etc.  Now you got essentially what you are after only 10X more rigid.

IMHO, building your own machine has one huge problem - making it rigid.  This is such a huge challenge that I would never try to make my own machine frame.  Just my two cents.

Karl


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## barnbwt

You mean essentially this?
Hardinge TM with a milling head on the horizontal bar
That does look attractive as far as the footprint and I love the idea, but for all the stuff that'd have to be replaced;
Spindle assembly (since these are all low-rpm units as best I can tell)
Ballscrews (so I'd have to ditch the ones I have & source new ones, like much larger than 16mm)
Linear guideways (maybe I get lucky & get a machine with good ways, but most of these machines look pretty rough <5000$)
Much more powerful servo motors (so I'd have to ditch my motors, amplifiers, and power supplies)

The mere fact the spindle would need to still be a scratch build makes dealing with that much iron less desirable.  And it's not even that much more; 900lbs vs. 6-700lbs.  Much of that is between the moving parts & the floor, too, and I could still make this machine a stand if I wanted (would be nice to keep a coolant tank & pump down there)

Maybe if I can get a broken down or incomplete machine for the price of just the castings it's worth looking into.  I'll keep my eyes open.

Also, the entire world supply of Horizontal mills is apparently in Rhode Island, which presents additional issues.


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## JimDawson

barnbwt said:


> I will have to do a LOT more research before I can determine whether/how those routines can be configured in the Galil so they are called up by the generic T(X) tool G codes.



You just set up a G53 (machine absolute coordinates) position and call it before a tool change.  This would put all of the axes into a safe position for a tool change.  In my software this is done with a mouse click, the G53 routine is already in there.


----------



## barnbwt

JimDawson said:


> You just set up a G53 (machine absolute coordinates) position and call it before a tool change.  This would put all of the axes into a safe position for a tool change.  In my software this is done with a mouse click, the G53 routine is already in there.


Wonderful, I was hoping that it would be fairly straightforward


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## JimDawson

Just to expand on this a bit, there are two coordinate systems in my software, the Work Coordinate System (WCS) and Machine Coordinate System (MCS).  The WCS is relative to the work and tool offsets are applied, the MCS is absolute relative to the axis home positions.   The difference between the two systems is set when you set the tools.  This is again is done with a mouse click for each tool and is stored in the machine parameters.  The Z WCS is set when you load the G code file, the X (and Y in this case) is always set relative to the spindle centerline, this is stored in a file attached to the G code file.  The only time you have to reset these values is when you change the tools.


----------



## barnbwt

So I'm still crawling down this Y-axis rat hole for the time being...

I'm trying to figure out my motor-mount layout, and have been looking at some industry implementations; between the 6" motor, 2" encoder, 3" coupling, and 4-6" reducer, the stack hanging off the ball screw mount is a long, heavy, awkward abomination.  How is this dealt with in the 'real deal' machines, or do they just cantilever stuff way out there & roll with it?

I did find some nice +4000rpm right-angle Nema 23 planetary reducer gearboxes out there (and not insanely expensive, surprisingly) but that doesn't seem to solve the problem much.  Actually kind of makes the cantilevered loading worse, but at least keeps the machine envelope small.  I was really surprised to see +4000rpm worm drives out there too (didn't know they could do that) but only in comically large sizes for this application (5" cube)

The closest thing to an 'elegant' solution I have now involves a wider/taller tool plate, hollowed out underneath for the ball screw stuff which lays right on top of the servo, linked via 8:1 25mm belt.  Most concerning is the loss of material, which leaves the tool plate looking like a U-channel with a .5" thick floor.  I'm just not sure how much it would impact rigidity for the load path to take the longer route up & over the hollow portion.


----------



## JimDawson

Maybe I'm missing something here but why do you need to gear down the servo so much?  I'm not sure any reduction is needed.  Both my X and Z are direct coupled to the ball screws, granted my servos are more powerful, but they are moving 2500 (or more) lbs of carriage.  They are both cantilevered off of the frame.

If gearing is needed, then why can't you use a belt drive and tuck the motor back under the frame on a mounting plate, or maybe off to the tailstock side in the case of the X axis.  You could do the same thing in the Y axis, put the motor at the bottom rather than the top of the assembly.  That way it would be under the Z axis drive system.  The Z axis servo could go at either end of the machine, where ever there is the most empty space.  It might make sense to put it on the tailstock end to get it out of the way of the spindle hardware.

Just some things to think about


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## barnbwt

My servos only generate about 45 oz-in of torque, but spin most happily at around 3000-4000rpm.  I only need about 500rpm on the ballscrew to get the rapids I'm looking for, so an 8:1 reduction seems like the obvious course of action.  That also gets me about 1000lbs of holding force on each axis.  That's just a really fast input RPM, though, so I'm not sure the best way to access it; a rated gearbox is the most obvious answer, since I don't know what the speed limit on 25mm timing belts is.

The cantilever of a reducer, servo, and encoder would be 10-11" off my mount; it just seems goofy when the X-axis rails are only 16" long themselves.  Also makes the machine much, much larger.  The right angle boxes work, but you still have a 12" long lever arm on the 6" rail spacing which also seems goofy.  I'm well aware the rails can take it; that little moment is nothing, it just looks silly & 'wrong.'

Belt drive seems to be the best option at this point, even if it does mean a lot of the Z-axis carriage structure gets blown away.  Assuming it can go fast enough.  There's still enough space to bridge the two X rails with some pretty beefy braces, so maybe that's good enough.






Please let me know if hanging the headstock off the rails is stupid for some reason; it seems like a nice way of making the machine shallower (but taller) and potentially giving better access for swarf cleaning etc.  Oh, and God bless Hiwin & Electrocraft for having auto-generating CAD filer tools on their websites.  The big black cube is the Baldor BLDC spindle motor.




The spindle is also coming along nicely, closely based upon the previous design (the main purpose of all this CADdery is to move the design into Fusion vs. NX while incorporating changes & lessons learned).  The casing is 4.5" OD, 45x85x19mm bearings, 5C bore.  Spindle is extra long since I'm not certain how to implement the pulley, brake, and possible collet-closer just yet.  I think I've got a handle on how to go about the assembly/disassembly though;
1) Press AC bearings into nose of casing against an internal abutment (per Hiwin dimensions)
2) Press spindle shaft & nose cap (for labyrinth) through AC bearings while supporting their inner races.  Tail of spindle is a close slip-fit
3) Bolt on fixed nose cap (mating portion of labyrinth) to casing
4) Slip spacer sleeve over spindle tail against inner AC races, slip rear DG bearing onto spindle & into slip-fitted casing*
5) Torque a jam nut against the DG inner race to clamp everything along the spindle axis, then stack the pulley/brake/closer on that

Disassembly is done by removing the fixed nose cap & DG bearing/spacer, bracing the spinning nose cap, and pressing the spindle out the front.  The AC bearings are driven from the casing by driving a tube against their outer races from the rear.

*Please let me know if an inner & outer slip fit for the deep-groove pulleys handling the pulley load is a bad idea; it seems like the best way to allow both inside & outside AC races to be press-fitted.


----------



## JimDawson

barnbwt said:


> since I don't know what the speed limit on 25mm timing belts is.


Easily more than 5000 RPM, I have run 8x50mm belts faster than that with 10 to 30 KW drives.



barnbwt said:


> Please let me know if hanging the headstock off the rails is stupid for some reason


Looks like it would work. As far as I know, the rails are rated the same in any orientation.



barnbwt said:


> Please let me know if an inner & outer slip fit for the deep-groove pulleys handling the pulley load is a bad idea



That's the way most mill spindles work, so I don't see why it wouldn't work in this application.


----------



## barnbwt

JimDawson said:


> Easily more than 5000 RPM, I have run 8x50mm belts faster than that with 10 to 30 KW drives.
> 
> 
> Looks like it would work. As far as I know, the rails are rated the same in any orientation.
> 
> 
> 
> That's the way most mill spindles work, so I don't see why it wouldn't work in this application.



Fantastic, it sounds like I'm on the right path, then.  The one concern I have with the headstock rails is that the spindle centerline will have to cantilever about 3" past the fixed carriage mounts; otherwise the mounts get in the way of the long tools toward the bottom of the toolplate (same reason fixed rails can't be used).  Now, I expect a 3/4-1" thick mounting trunnion at the front/rear of the spindle casing tied to those carriages should be rigid enough for end-work when dropped down low, but it still gives me pause.

Maybe stagger the one guideway furthest from the toolplate so it hangs down lower?  The tools could stick out up to 6.5" without any worries that way (versus the 'infinite' clearance they have now), and I suspect anything longer would require drilling past the collet nose simply to control run out; at that point there's no side-turning to do, and the other long tools would have to be omitted so the toolplate could drill to full depth anyway.  I don't have plans to try and fit such a large boring job in this rig, but it never hurts to think ahead.

I accomplished today's mission of tracking down & ordering the connector for my 24V power supply*, but man it was hard fought.  I was *this* close to saying "screw it" and ripping out the goofy pin headers & replacing them with something normal.  Two hours of scouring the net for traces of the defunct Cherokee International company's specs, and two more scouring Digikey for the correct connectors & contacts, and in an available version without a 10,000 piece minimum.  But in a week or so, I'll be able to power the motion controller on for real, and get it talking to the PC.

Jim, do the Galil communicate over a typical network cable, or do they need one of those crossover versions?  The manuals don't seem to specify, so I'm guessing it's the normal type, but I wanted to ask on the off-chance I can avoid some frustration.

*The connectors that came with the unit have a very goofy V-notch style connection to the wires, and once I'd replaced them with the wire for my power cable, the connection was very unreliable.  Solid enough to check voltages and pin-outs, but nowhere safe enough for delicate electronics


----------



## JimDawson

My concern with not having the spindle rigidity attached to the machine structure would be chatter issues.  Since you're using NX, you should be able to run some vibration analysis on the system to see what it looks like.  Having the spindle support structure cantilevered might be an issue.  Additional mass might be your friend here.

I know the Galil can use normal cable, and I recall you can use a crossover also.  I think it has an auto sensing port.


----------



## barnbwt

Yeah, it may be a good idea to use a fatter rail & screw on the headstock for that reason.  Japanese ones, too.


----------



## barnbwt

I've come across a handful of Swiss style lathes that have sliding/articulated sub-spindles (X-axis, though); I will ask around about their capabilities as far as turning vs. just drilling.

My thinking is that if the headstock is more rigid than the tool plate (probably heavier, larger/higher quality rails & screws, possibly clamped or pinned into fixed positions vs. truly articulated on the fly for most things) it won't be the limiting factor for chatter & accuracy.

I will try to do some sort of flexure analysis; I'm curious if this arrangment is more or less rigid/dynamically undamped than three axes stacked on top of each other.  It's kind of telling that a 3 axis Hurco turning center carriage is nearly as massive as the head stock casting above the base.  If stacked 3-axes high, my spindle height above the base would go up by over 50% (since the tool plate would need to move up to utilize the drilling tools.  Usually that increased swing capacity in a lathe is a win-win, but we all know that the longer load-path between tool & workpiece requires exponentially more mass to remain rigid.  By the same token, minimizing swing to the minimum necessary should likewise reduce the amount of mass required overall.

It looks like 5C faceplates are available up to ~6" diameter (and I'd be terrified of a fast servo running away with anything larger), and that's about what fits with the currently proposed Y-axis setup; anything larger is wasted space as I see it.


----------



## JimDawson

That's the way vibration is controlled in my lathe, everything is massive, and then damped with a few thousand lbs of special concrete.  Even the small lathes , EMCO for instance, is filled with concrete.



barnbwt said:


> ......... (and I'd be terrified of a fast servo running away with anything larger)............



We're going to try to prevent that from happening   We'll have encoder loss detection and excess position error shutdown.  For initial testing, we'll limit the command signal to a very low value, using the TL command, until we know that everything is correct.


----------



## barnbwt

JimDawson said:


> That's the way vibration is controlled in my lathe, everything is massive, and then damped with a few thousand lbs of special concrete.  Even the small lathes , EMCO for instance, is filled with concrete.
> 
> 
> 
> We're going to try to prevent that from happening   We'll have encoder loss detection and excess position error shutdown.  For initial testing, we'll limit the command signal to a very low value, using the TL command, until we know that everything is correct.


I planned on using .25" wall box tube for the frame, and filling it with lead in most areas.

I'm an aerospace guy, so I'm always convinced you can get away with only making the right spots rigid


----------



## barnbwt

So, after looking at some Swiss Lathes (Maier ML20, for example), it appears they have a Y-axis sub spindle of very similar geometric layout to what I'm planning.  Talking with some of our machinists, the sub-spindles are perfectly capable of turned side-work in addition to axial end-work, despite not being particularly massive compared with what you normally think of as a spindle headstock.  Of course, what the sub can do is limited by the stick out of the material being completely unsupported, and the max stock diameter being small for a Swiss lathe.






(sub spindle is the one at the left; the spindle at right is the primary, but doesn't really do much rigidity-wise in the X/Y directions)

I did notice the bedways are rather wide compared to the small sub-spindle size; they're wider than the spindle is long.  In that sense, the guideways are 'sized' like the footprint of a full size spindle headstock.  I think I should try to maximize that spacing as much as I am able in my build.


----------



## JimDawson

Wow, there's a lot going on there.  But I don't see a Y axis (headstock).  What I find interesting is the headstock moves as the Z axis, never seen that before.  And it appears that the sub spindle moves in both the X and Z direction.


----------



## barnbwt

JimDawson said:


> Wow, there's a lot going on there.  But I don't see a Y axis (headstock).  What I find interesting is the headstock moves as the Z axis, never seen that before.  And it appears that the sub spindle moves in both the X and Z direction.


Sorry, it's labeled +/-X2.  My scheme is the same idea, just turned up a 30deg incline.  The wide, flat striped thing in the bottom of the view is the bellows-cover for the sub spindle X axis ways.

All Swiss lathes feed the headstock along Z, since the tool plate (vertical wall section in the middle) only moves along X & Y, and therefore only cuts across a plane right in front of the rotating guide bushing.  Think of it like a follow rest, only the rest of the lathe moves relative to it & the saddle for a Z move.  A Z's are done via bar-feeding.  Very, very rigid setup very, very, very resistant to chatter & workpiece deflection.  Only trouble is you can only cut once, since you lose your bushing support if you pull the workpiece back in after a pass.  Everything, even 1/4" radius reduction on a 5/8" bar, has to be done in a single pass.  The machine above is about 4x4x8 in size plus the shrouds, so this scheme allows for incredibly rigid machines in a small space.

My proposed scheme is a hybrid, where the tool plate does the Z moves (which is nice in that it gives more flexibility for workpiece shape/size, as well as order of operations), but the spindle is still articulated along Y like a sub.  I really like the concept since it should make setting up precise tool offsets much easier than without a Y axis, and of course it also packs a ton of tools into a small space just like a Swiss.  Plus, I like the idea of only having 2 axes of backlash between the workpiece & frame, and tool & frame.


----------



## footpetaljones

I've seen a few machines that have the Spindle move in the X direction. The majority of them are chucker lathes, as you can't run a bar feeder with them. The Hasegawa TZ25 is one of them. Link here

The Quicktech i42 Eco is an example of an XYZC lathe with a fixed headstock. Link here

Whether you go with a moving headstock, or fixed, I would encourage you to make the tool plate vertical rather than at 30 degrees. When dealing with slant beds, alignment is more difficult versus machines that have a flat surface with everything else is 90 degrees to it. Having the tool plate vertical has the benefits of saving space and having the best possible chip evacuation.

I can't see how having the spindle hanging from the rails saves any space over mounting the rails below. It will add a lot of frustration to trying to bolt the motor in while holding it up, for sure.


----------



## barnbwt

That Hasegawa is a very similar concept.  Just with a Swiss style toolplate vs a turret, so a tailstock or guide bushing is theoretically viable.

I'm sort of confused about the incline/alignment bit.  The 60deg slant gives you room for support structure beneath the rails, but also shortens depth a bit.  Being vertical would require a bunch of structure behind the rails, so the depth overall wouldn't be much different (I think).  The X and Y are orthogonal, for what that's worth.

The reason I put the Y axis/spindle rails above the spindle was because of the incline.  The rails move with the spindle (the carriages are fixed to the frame), so putting them above has the effect of sitting them a little further back inside the machine.  That should minimize how much they will protrude toward the operator, so that should keep the housing smaller.

I'm hoping the motor/headstock will be more accessible in the hanging arrangement with that void beneath them.  It also lets me set tools with cranking the saddle out to Z maximum travel.


----------



## barnbwt

Well, the board has been powered up, and no blue smoke was emitted.  I also have no idea what I'm doing so it's gonna be slow going 

I have managed to perform a hard reset (huzzah!) which cleared out the previous IP address, and more importantly, subnet mask that is incompatible with my local network.  As it was, the devices could see each other (so the controller showed up in GalilTools), but they were not allowed to talk (indicated by the detected IP address being greyed-out)

Hard reset (jumper between the JP2 pins near the edge of the board marked "MR" before a power-up cycle, then turn off & remove the jumper, start up as usual before going into GalilTools; the pins' tails "go through" the SDM-20640 daughter board conveniently enough so the board did not have to be disassembled) put the unit into the default state where none of the addressing has been fixed, and the GalilTools software is able to see it.  At that point the model info and serial number were detected, and I could assign & 'burn in' the new comms info, which was set to be a very similar IP address to my other devices on the router & identical subnet mask.  Now GalilTools can see it!  So far so good, at least the board's not fried AFAIK.

Oh, I fully expect to have to do this at least a few more times, which is why I'm writing it down; I've messed with ethernet router stuff just enough to know that the IP addresses get changed frequently, so I expect the router to lose communication until I figure out how to nail it down (that is, I'm not assuming the PC is a static address that the controller can always dial up upon startup)


----------



## Karl_T

Once you are running, try a master reset from the command prompt. change a value then,

You have to enable control characters, then:


*<control>R<control>S
*

*FUNCTION: *Master Reset


*DESCRIPTION:
*

This command resets the controller to factory default settings and erases EEPROM.


A master reset can also be performed by installing a jumper on the controller at the location


labeled MRST and resetting the controller (power cycle or pressing the reset button). Remove


the jumper after this procedure.


*USAGE: DEFAULTS:
*

While Moving Yes Default Value -


In a Program No Default Format -


Command Line Yes


Controller Usage *ALL CONTROLLERS*


----------



## Karl_T

P.S. Keep a record of all changes as you verify what you want along with the command to change that parameter. then we can make up a .dmc file to download them all. if you ever suspect SOMETHING got farked up. do amaster reset, followed by a run of this .dmc file.

mine also includes all the subroutines all the motor PID data etc.  I can then put it all in another galil card in a few seconds.


PS I just scored a Galil 1880 card, title slightly mis- labeled on eBay, for $175. Tested it a couple days ago and it works fine. Hope you don't think I paid too much, they are about $3K new.


----------



## Karl_T

posted to wrong thread. my mistake - deleted


----------



## JimDawson

barnbwt said:


> Oh, I fully expect to have to do this at least a few more times, which is why I'm writing it down; I've messed with ethernet router stuff just enough to know that the IP addresses get changed frequently, so I expect the router to lose communication until I figure out how to nail it down (that is, I'm not assuming the PC is a static address that the controller can always dial up upon startup)



What I like to do is use the PC's onboard Ethernet port only for communicating with the Galil and fix that subnet, then use a seperate USB Ethernet port to connect to the world if needed.



Karl_T said:


> PS I just scored a Galil 1880 card, title slightly mis- labeled on eBay, for $175. Tested it a couple days ago and it works fine. Hope you don't think I paid too much, they are about $3K new.



SCORE


----------



## barnbwt

Karl_T said:


> P.S. Keep a record of all changes as you verify what you want along with the command to change that parameter. then we can make up a .dmc file to download them all. if you ever suspect SOMETHING got farked up. do amaster reset, followed by a run of this .dmc file.
> 
> mine also includes all the subroutines all the motor PID data etc.  I can then put it all in another galil card in a few seconds.
> 
> 
> PS I just scored a Galil 1880 card, title slightly mis- labeled on eBay, for $175. Tested it a couple days ago and it works fine. Hope you don't think I paid too much, they are about $3K new.


Nice.  I'm using a laptop so PCI cards are a no go (including graphics cards, *sigh*), but those are functionally the same as their external controllers for the most part, right?  Thanks for the tip on the .dmc file; that's very handy.


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## Karl_T

The PCI bus is far faster, recommended if you are high speed surfacing with monster gcode files and tiny moves per line. At least that is the case with Camsoft where the code is fed to the galil controller one line at a time.  

Also helps with high speed lathe threading where a high speed input from an OPTO-22 input is used to start the thread cycle.  In this case, I also increased the scan rate of the Galil card to maximum.  This effects all the PID tuning so you may want to look into this early on. I'd first ask Jim how his control handles lathe thread cycles. He may not have implemented all the features you can get with two line G76.

In general you'll be fine without this, a dedicated LAN like Jim suggests is going to handle things.


----------



## JimDawson

Karl_T said:


> I'd first ask Jim how his control handles lathe thread cycles. He may not have implemented all the features you can get with two line G76.



I don't have a single point threading cycle set up yet because I haven't needed it, but it could happen pretty quickly.  My software does do rigid tapping, and with live tooling does thread milling.  Once I get my current press project out of the way and get another customer's router upgraded, I'll get back to getting the lathe software finished.  Should be able to start back on that by the end of the month.


----------



## JimDawson

Karl_T said:


> The PCI bus is far faster, recommended if you are high speed surfacing with monster gcode files and tiny moves per line. At least that is the case with Camsoft where the code is fed to the galil controller one line at a time.



I use a deep look ahead, about 500 lines into the command buffer, so that the motion is continuous.  I can do this because I compile the DMC code on G code program load.  The software keeps the command buffer full during the run.



Karl_T said:


> I'd first ask Jim how his control handles lathe thread cycles. He may not have implemented all the features you can get with two line G76.



I don't have a single point threading cycle set up yet because I haven't needed it, but it could happen pretty quickly.  My software does do rigid tapping, and with live tooling does thread milling.  Once I get my current press project out of the way and get another customer's router upgraded, I'll get back to getting the lathe software finished.  Should be able to start back on that by the end of the month.


----------



## Karl_T

High speed lathe threading is a different approach than tapping or thread milling where an axis is slaved.

First get a high speed input to time an index mark. I used a slot sensor because it has response times in the 10EE-6  seconds range. many others have amplified the Z index pulse.

look at this input for a second or so to get an exact lathe RPM, lock the speed, calculate your feeds based on this.

Now fire each lathe pass the instant the high speed sensor trips.


if you want to do all the features possible with two line G76, you're in for quite a programming adventure.  I did this and it took weeks to implement.


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## Karl_T

here's the operator instructions for G76


'*******TWO LINE FANUC G76 INSTRUCTIONS*********************

'NOTE: Use G0,G1 to position machine at start of thread(Z) and retract height(X) before G76 lines.
'      Important: X position determines ID or OD threads


'EXAMPLE G76 LINE 1 FOR 1/2" ROD 20 TPI
'G76 P011060 Q50 R10
'first two digits after P number of finish cut passes
'second two digits after P number of leads to pull out/10, 10 is 1 lead
'third two digits after P is tool tip angle, tool will infeed at 1/2 this angle
'Q is minimum DOC cut in tenths, example 50= .0050 depth radius
'R is DOC finish passes in tenths
'S is optional spindle speed, spindle must be running with an earlier M3 M4 code

'EXAMPLE G76 line two 1/2" rod 20 TPI .5" long 1 thou taper (Z 0 at start of thread)
'G76 Z-.5 X.4567 P433 Q100 F.05 R.001
'Z is end of thread Z value
'X is final diameter of thread value; minor dia. on O.D., major dia. on I.D. (LH) threads
'P is thread height in tenths, 433 is .0433 high, generally COS(infeed angle)*1/thread pitch
'Q is depth of cut for first cut in tenths
'F is feed per thread, 1/LEAD for US  
'R is for tapered threading difference in X from start to finish in Z


attached is my camsoft code for this cycle.  syntax is all wrong but logic is logic. scan it for concepts to attack.


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## JimDawson

That would work.  I was thinking about a different approach, using the axis gearing and slave the Z to the spindle.  Once it sees the index, then fire the gearing, but using the GD (Gear Distance) command, ramp the Z up over 1 rotation of the spindle, that way it doesn't jerk to a start.  This would compensate for any variations in the spindle RPM during the cut.  Then at the end of the cut, just issue a GRn=0 command to disengage the gearing.


----------



## barnbwt

Okay, making a little more digital progress here; I have managed to load the configuration file that sets up all the system variables (starting points for servo tuning, limit switch & E-stop behavior) and canned cycles (the 'guts' of the G-code commands, the part that is actually translating G-code to DMC language), and burn this file to non-volatile memory, using GalilTools (open file, download to the device, type BP in the command line to burn it)

Now I can call up variable values from the controller & get the numbers set by the configuration file.

I think I will focus on completing the corporeal design layout for the time being, since I can already see that a number of aspects of the configuration file Jim provided me will need to be modified (his is a 4-axis controller not an 8-axis, for starters).  It's probably easiest to get that nailed down, now that the controller is shown to be working.

On that note;
Are Misumi guide rails any good?  Also, should I prioritize quality of ballscrews over quality of rails?  I would like to get the X and Y directions very rigid since that's what the cutting force is spanning, and I'm not sure what the order of importance is (frame, screws, guides, powertrain).  My concern is that a spring-loaded double ball nut won't be good enough to control cutting forces.


----------



## JimDawson

I'll configure the software for the number of axes needed once I have an idea of what is needed.  As of right now I understand you will be running 4 axes.  Spindle, X, Y, and Z.  My lathe is actually running 5 axes, Spindle, X, Z, Live tooling, and Turret.  I have an additional single axis card that runs the turret.

Order of importance?  Everything is important 

Misumi is a reputable company as is Thomson.  I would guess that if the nut is rated for the calculated cutting forces (plus a generous margin) that it would work fine.  Thomson makes some that have a threaded adjustment, one nut screws into the other, quite nice for compensating for wear down the road.

Just as a guideline, I just measured the rails on the Haas mill, 25mm.  That's a high speed, 5500 lb machine with a 7.5 HP spindle, the ball screws look to be about 25mm


----------



## barnbwt

"Everything is important" well that's not very helpful...

Right now I have 16mm screws and 20mm rails for X and Z, both Chinese (and using DIY double-nut for backlash control).  I was thinking of going with 25mm rails on the Y/spindle mostly because it's heavier, but it sounds like that's probably not going to change anything, so 20mm it is.  I am also considering ground (lightly used) preloaded 20/25mm screws on Y and maybe X.  But if I'm using a rail-brake on Y for most things, maybe X is the 'important' axis as far as controlling cutter rigidity?  I think the only time Y could ever be used dynamically would be end-engraving; I sure don't plan on trying to do coordinated X/Y milling or anything like that, but if it's only another 100$ for the capability...maybe.

Something along these lines for the ballscrew(s) on X & maybe Y


----------



## JimDawson

barnbwt said:


> "Everything is important" well that's not very helpful...




If the rails are reasonably good quality then I would say use what ya got.  20mm should be plenty for this size of a machine, a customer has a 5x10ft router and it has 20mm rails.  16mm ball screws should be good also, my lathe has 25mm ball screws but the carriage assembly weighs more than a small car.  If your double nut system works, then that should be fine.  If that is what is spring loaded, then I would make an adjustable hard adjuster to replace it.

For rigidity, mass is your friend.  The ball screws will position the tool just fine and have plenty of push to overcome the cutting forces, but the mass of the system is what damps the high frequency vibrations (chatter).


----------



## barnbwt

Yeah, my plan is still to try to 'cheat' my way to rigidity by making the support distances as short as possible, and packing dense material like lead in wherever I can.  Only so much you can do in this size envelope.  I figure if distances are short & the parts rigid, those frequencies should be shifted so high they don't resolve in the finish; kind of the opposite approach to the dampening model, I suppose.  My suspicion is the small-size tooling will be the real limiting factor for chatter, no matter what I do upstream, so long as things are rigid.

Found this interesting video with a very similar gang tool setup to what I'm pursuing (includes the guy hilariously chasing an annoying on-screen fly with compressed air)





At this point I'm going with 3/8"x3" turning tools and 1" diameter sockets for the shanked tools (that's the same size as my Foredom rotary, as well as a number of air motors, for that "one day" live tool addition).  There's just enough space for ER25 collet nuts to clear each other, so anything smaller would be viable.


----------



## JimDawson

That is an interesting gang tool setup, never seen one quite like it.  Also never seen a 3 jaw mounted in a mill spindle before.  Very cool !

Using tools of that size, your cutting forces are going to be quite low, so what you are proposing should work fine.


----------



## barnbwt

I notice that nearly all linear guide blocks have threaded holes (including mine), but there are a few with bored through holes.  Since my toolplate is about 3.5" thick, it seems like threading into it vs. drilling through is a lot more convenient.  Thoughts?  I'd rather not bore out the ones I have unless the pros outweigh the cons.

I also rejiggered how I am doing my turning-tool clamps (they are in pairs between tools, vs. staggered) and now have room for MT1 drill sockets (for short tools) if I really want them --only trick would be figuring out how to tap them back out from the rear of the taper, when it's a solid block of toolplate back there.  So that's a total of 20 tool positions at this point.  When the stock is only 1" max diameter it can fit between a lot of obstacles.

Another necessary change that may have a fortuitous, if unusual consequence was hanging the toolplate out 1.5" past the X-axis guide blocks nearest the spindle.  This was done so I'd have access to the underside/backside of the tool plate where the ER25 collet holders plug in, so they could be secured with a pair of set screws (not super convenient, but better than all my other ideas).  It's less than a 1:2 cantilever ratio so I'm not super worried about loss of rigidity, but it does mean the Z-axis guide rails can set back 1.5" from the spindle accordingly...leaving a very narrow gap-bed, that could accommodate a large diameter 5C face plate ('large' meaning <10").  Obviously I wouldn't spin the poor thing at 4000rpm, but it opens the door for respectable-sized sheet engraving using Y/C polar coordinates, and at the least improves user access at the tool change area.  Maybe I could produce my own vinyl press-masters, lol.


----------



## JimDawson

barnbwt said:


> I notice that nearly all linear guide blocks have threaded holes (including mine), but there are a few with bored through holes.  Since my toolplate is about 3.5" thick, it seems like threading into it vs. drilling through is a lot more convenient.  Thoughts?  I'd rather not bore out the ones I have unless the pros outweigh the cons.


These are the ones I bought for my press project, I had the same problem, about 2 inches of steel to drill through, and I needed the wider hole spacing to accommodate the connecting rod.  https://www.mcmaster.com/6709k13




> I also rejiggered how I am doing my turning-tool clamps (they are in pairs between tools, vs. staggered) and now have room for MT1 drill sockets (for short tools) if I really want them --only trick would be figuring out how to tap them back out from the rear of the taper, when it's a solid block of toolplate back there.  So that's a total of 20 tool positions at this point.  When the stock is only 1" max diameter it can fit between a lot of obstacles.



Drill a small (3/8 ?) through hole to use a punch from the back?  



> Maybe I could produce my own vinyl press-masters, lol.



Great idea


----------



## barnbwt

JimDawson said:


> These are the ones I bought for my press project, I had the same problem, about 2 inches of steel to drill through, and I needed the wider hole spacing to accommodate the connecting rod.  https://www.mcmaster.com/6709k13
> 
> 
> 
> 
> Drill a small (3/8 ?) through hole to use a punch from the back?
> 
> 
> 
> Great idea


Tool plate is about 8" square, MT1 is about 2" long...that's a 6" deep hole.  Doable of course, but seems like it'll be a pain.  Right now I have a couple large diameter holes drilled/milled from the top, so a stout 'pry bar' can be tapped to knock them loose.  I don't know if that would do better than a long punch, though, and at least that way I could use the spindle to drill the holes in place.  The impact from either on the taper wouldn't damage the guideway bearings, would it?  Surely they're not that delicate.


----------



## JimDawson

The bearings are pretty tough.  It normally does not take too much to knock out a MT, especially a #1.  A wedge might be the best if you can get to the hole.  That's what's normally used to remove a MT form a drill press spindle.  Just butting up against the tailstock screw will knock them out of a lathe tailstock.


----------



## barnbwt

Ah, a wedge; I like that.  Just remove a little plug, drop the wedge in the hole, and carefully tap it downward. Can even make the hole a simple drilled pocket about 1/2" or so diameter.  You'd just have to make sure all your tapers are long enough to get at.

I figure they would only ever be used for center drills, but oddly enough those don't seem to exist in the MT1 size.  Won't be too hard to make them, though.


----------



## barnbwt

Apparently there are MT1 tools with wee little drawbars (screws, really), so I think the through-hole is back in the lead.  Not sure I think an MT1 fly cutter is a wise idea, but they're out there.

I have also perhaps a stupid question; I need a big honkin' step up transformer for my spindle servo (my drives can use up to 230VAC, servo is good to 300V IIRC) since my service will be 120VAC for the duration.  Having received a *second* badly defective Chinese model (this last one has exposed wiring where the insulation was burned off all over the place before it even got here) I've decided to give up and explore alternate options.

-Do these big transformers work the same in both directions (step up/down) or is there some one-way impedance thing?
-Do dry, wound transformers go 'bad'?  Should I be worried about buying a new/old-stock 2:1 industrial unit, besides the asbestos?
-Assuming the winding isn't burned from over-current, these things are pretty simple, right?  Conductor pair in, pair out?  Little to go wrong?
This one seems to fit the bill nicely (my spindle is 1kW max @ 300V, so 1.5kVA @ 240V should be plenty, plus this beast is 37lbs of copper)
https://www.ebay.com/itm/Dongan-1-5...Purpose-Transformer-80-1040-Used/173499024481


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## JimDawson

I would buy a used industrial transformer.  They rarely go bad, normally only from extreme overload for extend periods, unlikely in normal operation.

Yes, they work both up & down.

I don't think I have ever seen asbestos in a transformer, that would have to be a really old one.


----------



## Boswell

Barnbwt and Jim,  just want to let you both know this is a faninating thread and I have been following this build closely. Thanks for all of the great information.


----------



## barnbwt

JimDawson said:


> I would buy a used industrial transformer.  They rarely go bad, normally only from extreme overload for extend periods, unlikely in normal operation.
> 
> Yes, they work both up & down.
> 
> I don't think I have ever seen asbestos in a transformer, that would have to be a really old one.


I was thinking of an old slide projector me & my pa repaired a while back for an elderly family friend; took the housing off and the wire insulation was coming off as powder --"maybe we shouldn't do this inside the house..."


----------



## barnbwt

Boswell said:


> Barnbwt and Jim,  just want to let you both know this is a faninating thread and I have been following this build closely. Thanks for all of the great information.


Thanks,
Hopefully I'll be able to dive into the spindle cartridge before too long

On that note; has anyone ever played with a 'jig grinder' on a lathe?  Seems like it'd be the perfect way to get excellent bores & tapers, even more so than a toolpost grinder


----------



## barnbwt

I had a dumb idea for the 1" 'live tool' sockets; rather than the simple solution of a pair of set screws on the underside, have a concave-wedge between each pair of tools pulled upward by a bolt through the tool plate.  The added complexity seems to carry a number of advantages; I can see this scheme having more surface area/rigidity than set screws, it puts the fastener heads on the top side of the tool plate, and 4 fasteners would hold five tools.

Next dumb idea; form the obnoxiously-deep bores in the tool plate with sleeves inside an epoxy-sand casting.  As large (8x12x3.5) as the block has become, a casting makes much more sense than machining.  The density of holes may still be too great for that, however; I have no idea how brittle that material is.  And of course the various component & tool mounting surfaces would also need to be metallic inserts set into the casting.

I also had a less-dumb fabrication question; whether anyone has tried one of these 'weldment frame' builds using brazing; braze is plenty strong, causes less warping/stress, can be applied in an oven (though with a ton of prep-work), and would seem to have damping benefits over welding.


----------



## JimDawson

I like the wedge idea.  The only downside might be that if you wanted to change one tool, you might disturb the setup of the adjacent tool.

I assume the bores would be through the 8 inch dimension.  The bores would not have to be on-size for the full depth, just deep enough to accommodate the tool holders plus some clearance.  A reamer would work well here.  The balance of the bore could be an oversize counterbore from the back or a drilled hole that is smaller, or maybe a through hole would not need to be drilled at all.  The difficulty of making the part depends on what equipment you have to work with when building the machine, this is something that could be done on a BP type knee mill.  I would just build the block out of a chunk of 4150 or 4340.  It might take a couple of days to build it, but you only have to do it once.


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## barnbwt

JimDawson said:


> I like the wedge idea.  The only downside might be that if you wanted to change one tool, you might disturb the setup of the adjacent tool.
> 
> I assume the bores would be through the 8 inch dimension.  The bores would not have to be on-size for the full depth, just deep enough to accommodate the tool holders plus some clearance.  A reamer would work well here.  The balance of the bore could be an oversize counterbore from the back or a drilled hole that is smaller, or maybe a through hole would not need to be drilled at all.  The difficulty of making the part depends on what equipment you have to work with when building the machine, this is something that could be done on a BP type knee mill.  I would just build the block out of a chunk of 4150 or 4340.  It might take a couple of days to build it, but you only have to do it once.



Maybe do the 'wedges' as plugs tangent to the 1" holes?  That would have one screw for each tool.  Rather than a wedge, I'd take a 3/8" or so rod, mill a 1" diameter 'mouse hole' in the side that engages the tool, and blind drill/tap the end the tension screw goes into.  I think I've seen Chinese boring bar holders done that way, usually with the plugs in pairs.  That would take up about as much room as a simple bolt, but provide more contact surface & mechanical advantage (that you can also access from the top side).  I think smaller-diameter tools could still be used if a split-ring clamp or sleeve was employed.

To be honest, I'd actually planned on boring all the longitudinal holes with the machine itself, flipping the plate around 180 degrees if needed (obviously the holes from the first setup would be the 'not-precise' holes).  The only reason for the through-hole is so cables or hoses could pass through.  I also had the crazy idea that a die-holder could be fastened across the front of a 1" hole and the stock run through it (simply because the stock is at most 1" for longer parts).  Right now the tool plate is 12" long, so the motor & ball screw fit neatly between the X guide rails, which for ~1" drills seems like it's getting a bit long.  For the MT1 tapers, the ~3/8" through-hole for the drawbar would require an aircraft drill or cable drill.

I found (maybe) an affordable jig-borer which would be perfect for truing up the holes as well as the spindle taper;
1) predrill 3/4" x 2" holes in the tool plate using the unground spindle w/ runout (spin the block & repeat if needed, with first holes oversized)
2) set the jig borer into a hole, lock it in place
3) turn the spindle against the grinding stone along the desired taper & diameter to true it up
4) drill out the tool plate holes to near full size (and drill/ream out the MT1 through & taper holes)
5) set jig borer into the spindle, adjust it to grind out the holes to full, concentric diameter (maybe the MT1 tapers, too, if the stone can reach)

All that would be needed to be done before hand is;
-The slots for the square tool holders & clamps
-The threaded holes for the underside mounted parts
-The stepped through-holes for the wedge-plugs holding the 1" tools
-Maybe a grid of smaller tie-down & alignment pin holes on the top surface, in case I ever mount anything up there for milling?
-Maybe some mounting points on the upper/lower (along X) faces, for indicators or cutting oil nozzles or something?

That seems way more reasonable than effectively machining an engine block beforehand


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## JimDawson

Sounds like you have it under control.  I like the idea of doing the work in the machine.

Two locking mechanisms come to mind, first is a D1 chuck cam-lock system, and second, take a look at the Dayton Lamina Ball-Lock system. https://www.daytonlamina.com/sites/default/files/doc/920_BallLock.pdf  Both would be quick change, but maybe more trouble than they are worth.

All of my round tool holders are secured with set screws.  The normal lathe tooling is secured with a wedge lock system designed for square shank insert holders that bolt on to the turret.  Each of the turret stations is ported for through coolant, very handy for drilling, boring, and tapping operations.  Puts the coolant right where you want it.  The through coolant is only ported to the active tool and is fed from a pump separate from the flood coolant system.  I can post some pictures later if you want.


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## barnbwt

Sure, I'd appreciate that.  Like I said, the primary draw to alternative fab methods is due to the size of the toolplate; gonna be hard/expensive to source and process material at this size.


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## JimDawson

Here are some pictures

Square tool holder.  No, the picture isn't upside down, that is the way the tool presents to the work.  Note the wedge system.



One of the round holders, this one is 1 inch.  Ported for coolant.  If you plug off the front port, you can run coolant through the holder.  Sitting on one of the square tool holders without the wedges in it.



A 1 inch round holder with an ER32 collet chuck in it.  The ER32 is ported for through coolant, the aluminum plate on the back of the tool holder is the rear block off plate for coolant.  The coolant squirts out of the slots in the collet at an angle, pretty well aimed right at the drill tip.



This port is where the coolant is fed to the turret, there are a series of passages inside the turret to pass the coolant.  Only the station that is in working position gets coolant.  The tap is in the working position.  The device to the left is a bar puller, a must have if you don't have a bar feeder.




A tap in a ER11 holder, 3/4 shank, also has through coolant.



Here is a 3/4 drill bit directly in a 3/4 holder.  Note the slot ground in the bit, this is where the coolant comes through, one on the top, one on the bottom.  A block off plug is installed in the coolant port.



And the flood coolant system.  The aluminum welding rod C clamped to the tool setter arm is a visual guide to position parts that we were inserting by hand.  



You can just see the turret coolant feed tube at the very top, right of the carriage, just below the end the light




Maybe you can get some ideas from this.  The thing at the bottom right of the picture above is not a tailstock, it's a part catcher without the basket on it.  At the extreme lower right is the part conveyor, you can just see the edge of it. This lathe is not equipped with a tailstock.


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