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Some Ideas for Ease of Use

Discussion in 'CNC IN THE HOME SHOP' started by MontanaAardvark, Apr 25, 2017.

  1. spumco

    spumco United States Active Member Active Member

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    Cool. I think you're in business with the order of operations.

    I'd just hate to see the cartridge walk out a little bit before the bolt slams forward and have an out of battery ignition. If you're going to use it, and not just use it for buy-back bait, then keeping the chamber a little dirty might not be a bad thing.
     
  2. MontanaAardvark

    MontanaAardvark United States H-M Supporter - Premium Content H-M Supporter-Premium

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    I think Mark's idea was to put together something that can be fired for $20 or so. As a manufacturer, he has better source of materials than I do. When you figure shipping, I had to buy enough to make four with minimum quantities, and pay shipping. If you spread that out over four, I'm right around $50 each. There has never been a buyback around here, so it's going to be a toy to play with a few times.

    The extra work on the mill and weeks of machining lessons are not included.
     
  3. MontanaAardvark

    MontanaAardvark United States H-M Supporter - Premium Content H-M Supporter-Premium

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    Update, anyone? The frame is cutout, all the pieces are done and I'm waiting on one part to put it all together and do a test. It's the spring that makes the thing work.

    MachiningDone.JPG

    The whole piece was indexed from the screw holes in the test piece I cut.

    This is a new 20 x 7-1/4, half inch aluminum plate. I'm thinking of options for making it semi-permanent, or my default plate. Either drilling and tapping lots of 3/8-16 holes along with 1/8" tooling pins (because I have a box of them), or something else. I'm not sure what.

    Now it's back to more mill update plans and projects. I'm feeling the need to upgrade the motor and/or controller. Higher RPMs for the same power would be really nice to have; CNC control of on/off and RPMs might even be better. Higher RPMs might be different gears, but I don't know the options.
     
  4. spumco

    spumco United States Active Member Active Member

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    Sweet.

    I figured we should start a new thread since this is straying off the 'ease of use' topic, but you keep posting cool stuff and I'm a sucker.

    As for the mill, yes. Do all of the above, you won't regret it. CNC control of the spindle is pretty easy. Does your BOB support/have a 0-10v PWM output?

    While you're shopping for motors, do yourself a favor and plan on getting an encoder so you can rigid tap... Or at least a spindle index sensor. You can make an index trigger from an inductive sensor (limit switch) and a dumb old chunk of plastic pressed on the top of your spindle like a collar. Use set screws to trigger the sensor, and use 2 or 4 of them for balance. Mach3 can handle multiple index signals, and more is better for tapping.

    Basic shopping list for nirvana:
    - 1-2HP Motor w/encoder. If you get a really good one that has a 1000:1 constant torque rating you won't need a two-speed belt drive to do low-speed hogging and high-speed small end mills. You can fit an encoder that's WAY cheaper than the one that comes on the BlackMax motor. Really, you can fit a 56C sized motor on top. I managed to get a 182 on mine, but mine's bigger than yours....

    If you're worried about 1HP being undersized, don't. Good-quality motors are way under-rated, compared to the grossly-overrated cheap motors. I 'only' have 2HP, but I'd have no problem snapping a 1/2" tap in steel at 500RPM, or running a 3/8 3-flute in aluminum at 7k. Piles of chips, no gear or belt changes.

    Here's a peach: https://www.automationdirect.com/ad...0HP)/Marathon_Black_Max_(0.25HP_to_30HP)/Y535

    And another, WITH an encoder already on it: http://www.ebay.com/itm/Marathon-1h...616518?hash=item282e7cb4c6:g:TRUAAOSw4CFYytt9

    - Belt drive. Figure out your top speed, based on your bearings and smallest intended end mill speed. I can go to about 7400RPM before I chicken out, but I expect my bearing to die sooner rather than later, and then I'll replace them with really good ones. If you get an 1800RPM motor, and run it up to 5400RPM with the VFD (max safe RPM on that BlackMax), then a 1:1.3 or 1.4 belt drive should work well to get you to 7500RPM. A single-speed belt drive is way easy to sort out, and the cogged sheaves are pretty cheap and easy to get. You won't regret ditching the gear system, and you might even sell the gear set to someone as a replacement or backup.

    - VFD. I got a Hitachi WJ200 and love it. However, the Automation Direct GS-3 VFD's have an optional encoder input card - for a bit more money - that is superb. Takes 3-24VDC complimentary inputs and can work with very high speed encoders. Not something I realized when I bought my Hitachi was that the WJ200 is very limited in the encoder inputs. It's superb otherwise, and can even do positioning (servo-ish). Doing it again, I'd spend the extra $50-100 for the GS-3 VFD just to avoid the encoder input compatibility issues I had to work out.

    Even if you don't get an encoder, buy the best-quality motor you can and make sure it has the capability of accepting an encoder later on.

    The other option, of course, is to throw down on a servo spindle.

    DMM's 1HP, 5kRPM servo: https://store.dmm-tech.com/products/dst-0-75kw-ac-servo-motor

    And the matching drive: https://store.dmm-tech.com/products/dyn4-h01a2-00-dyn4-ac-servo-drive?variant=20982430342

    That combo would be rally, really sweet. Unfortunately, their "big" servos just don't have the top speed I wanted without gearing them up too much and lose low-end torque for big drills and tapping. For you, a 1HP servo would be pretty nice, and you might be able to find one on Fleabay.

    Gold Standard: http://www.ebay.com/itm/Parker-J092...469419?hash=item33ce00786b:g:zfoAAOSw7GRZC3FQ

    If you start a new thread "In Search Of the Ultimate G0704 Spindle" I promise I'll chime in.


    By the way, I successfully milled Grade 5 titanium for the first time today. I'm still new at this, so it was pretty awesome watching the mill make something round in to a hex. 2750RPM, .625DOC, .025WOC (adaptive), 5.5ipm, .250" 4F. Chips looked good, excuse the never-seize goo.

    And yes, I've got an approved Form 1 for those who may be unable to control their urge to chime in about such things.

    -S
    IMG_3418.JPG
     
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  5. MontanaAardvark

    MontanaAardvark United States H-M Supporter - Premium Content H-M Supporter-Premium

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    Let me get this straight: that hex head on the cap was once solid round titanium bar and you cut it to final size hex bolt head? That's very cool. Especially 5/8" DOC, skinning off .025 at a time.

    I've cut titanium on my Sherline mill and lathe: 1/8 HP. Much lighter cuts. OTOH, I thought it machined a lot like the couple of pieces of stainless I had cut by then (long ago).

    The rest of this is encyclopedic! I really should start an "Ultimate G0704 Update" thread, although I'm sure other people want things I don't. I was looking at Hoss' DVD again, at the supplemental projects and in particular the manual drawbar, which is probably going to be a high priority project so I can start on the TTS. He's using this motor, which is 5000 RPM, 120VAC and 1200 W input (1HP output), but has no encoder.

    I think my goal would be what the Tormach PCNC 770 says it's using: 1HP, 10,000 RPM. I'd settle for 7500 RPM, for sure. Those machines are in the same work envelope class as the G0704 and are rated for a 120V 15A outlet. I don't consider 1HP underpowered and will be happy to live with that. Putting a 2HP motor on a machine in place of a 1 HP motor doesn't make it a 2HP mill - at least in my mind. The mill is a system and has to be rigid enough to handle the motor that size, and that extends to every part, including the ballscrews I just put in.

    I have a 220 VAC outlet near the mill, but I think it's conventional 220 not three phase.

    My BoB has digital outputs and inputs but not a PWM encoded output.



    Bob
     
  6. spumco

    spumco United States Active Member Active Member

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    The chunk started as 1.25"OD bar stock. I turned the OD and ID threads and turned a .750 spigot. I then milled the spigot in to the 5/8" hex on the mill. Held it in a step collet that I bored to hold the threaded section - the little flange registered against the collet face and helped keep it rigid. It was only a couple of .025" passes since I wasn't going from 1.25 to .625. It turns out that getting the RPM and chipload correct for that material is the key - not that I figured anything out. I just pressed the "I Believe" button on the F&S calculator.

    The VFD's in the HP range you'll need convert 220V 1P to 220V 3P. They're like magical little computers with million page instruction manuals.

    What BOB do you have? If you've got a part number or model number I can check the specs and see what we can do with it.

    And I think 'encoded output' may be a misnomer or a term I'm not familiar with. Some BOB's can take a digital PWM signal from Mach3 parallel port or your ESS and convert it to a 0-10vdc output. VFD's usually require one of three input types to set the speed:
    1. 0-10vdc (common hobby method)
    2. 4-20mA (common industrial method, more RFI/noise resistant than 0-10vdc)
    3. Pulse + direction signals (rare in hobby world. You would use the output from an encoder - maybe on a conveyor belt roller - to drive a different VFD/motor combination probably at some speed ratio to the primary device).

    If your BOB really doesn't have a 0-10vdc output capability, there are spindle control sub-boards available to connect your ESS/BOB to the VFD. Or you could also get a new BOB that has a built-in PWM output and it would probably be an upgrade to your existing BOB with more inputs/outputs for your future auto tool changer, power drawbar, glass scale feedback for full closed loop operation, servo drive encoder signals, coolant, mister, auto oiler, and the kitchen sink timer.

    You can NEVER have enough inputs/outputs.
     
  7. MontanaAardvark

    MontanaAardvark United States H-M Supporter - Premium Content H-M Supporter-Premium

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    I have the C35S from CNC4PC.com. I have the manual .pdf and searched for PWM, motor control, and a few other terms.

    I'd rather not go down the road of the VFD unless I have to, though. Like I say, I'm OK with 1 HP and that size plugs into the 115V typical wall socket just fine.
     
  8. spumco

    spumco United States Active Member Active Member

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    You're right: the C35S doesn't have onboard spindle control. You have two options for computer control - simple on/off and you set the speed manually, or full control. If you're going to upgrade, I wouldn't bother with the simple relays-to-the-motor setup. Having the computer set the speed and direction isn't hard or expensive.

    For full control, you could get a C41 or C69 board from CNC4PC and mount it as a daughter-board on your C35S, but you'll still need to figure out what motor/controller combo (OEM or otherwise) you want and whether the OEM can use a PWM input.

    As for the VFD, they're available - and cheaper for lower power - in whatever HP rating you need for your motor choice. You need one if you switch to a 220-3P motor, regardless of HP. The nice thing about moving to 220-3P is that the motors are quieter, generally better built, and use fewer amps per horsepower (smaller wire, less heating) than the equivalent 110-1P.

    If you prefer to stick with the OEM motor, there are a ton of resources available to help you set it up under CNC control. Smarter folks than me have written tons about upgrading your mill. Poke around on the Mach3 forum and CNCZone and you'll find what you need. If you followed Hoss' plans for your conversion, you should go straight to his site and just copy whatever he did for spindle control. That guy is frikkin' clever.

    If you want to move to a non-stock 3P motor & VFD combo, I can help a bit. Also, if you want to upgrade your BOB to something with on-board spindle control, I have an unused C23 available at a steep discount.
     
  9. MontanaAardvark

    MontanaAardvark United States H-M Supporter - Premium Content H-M Supporter-Premium

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    I spent a few hours in the last couple of days getting my fourth axis running. I'd wanted to add a rotary table since the start of the project and have added parts along the way. Pretty much every time I bought needed parts, I got extras for the fourth axis. I picked up the 6" rotary table itself last November on a Black Friday sale at Wholesale Tool, and everything has been sitting in a corner while I finished CNC converting the mill.

    I had a leftover NEMA23 motor mount from when I started out doing Hoss' Phase 1 conversion, and two sets of standoffs. I had both too long and too short. All I had to do was figure out how to get the hand crank off the table, then drill and tap two holes in it and two clearance holes in the motor mount. And cut four standoffs down to size.
    RotTab2.JPG

    Tweaked the Mach3 Motor Tunings in and it works fine. I can't actually use it yet, because I don't have any Tee nuts that fit the slots on it. A 7/16 nut from my mill is too big, so I'd guess a 3/8" Tee nut would fit it. There's probably a complete clamping set for that size slot out there somewhere. Minor annoyance in Mach3: it interprets the IPM numbers in feed as degrees per minute. If I'm running 1.3 IPM, like I was for the small slot in steel, then told the table to go 90 degrees, that move would take an hour and a half. When I was testing this, I ended up at 3600 degrees/minute to run 90 degrees in a "reasonable" time - about 5 seconds including acceleration and deceleration

    My only gripe with the motor on the G0704 is the speed, although it also seems kind of noisy to me. The spindle runs smoothly and while I measured the runout when it was new, I don't recall anything bad. The part that sticks out of the top of the headstock and has the bolt for the collets or EM holders has a very pronounced wobble to it, though. I assume noise translates into losses (friction) in the bearings. A quieter, smoother motor would be nice. I don't know that the motor is too noisy. It's not like I feel I need hearing protection, and I'd be pretty sure it's quieter than a lot of other tools like my table saw.

    Time to do more reading and research.
     
  10. spumco

    spumco United States Active Member Active Member

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    1. Awesome. Figuring out - sort of - 4th axis CAM has been challenging for me. Manual indexing is easy, but getting the integration between operations has been fussy (my post processor is wonky and I don't know how to edit it very well).

    2. I'm in the same boat for speeds since mine is also based on a worm-drive table. Mine was CNC from the get-go, but is also slow. I suggest you bump the max speed after ensuring you have good lube in the gearbox. I ended up at about 15RPM before it becomes unreliable. Another good tweak to increase the rotation speed is to bump the max feed rate but cut way back on acceleration. This allows the backlash to be taken up from a standstill (or direction change) without binding the gears and losing steps. I have also a 90:1 ratio and can get 15RPM - whatever that is in steps/degree/second. This setting will, of course, depend on your microstepping and gear ratio, but I suspect you can go a bit faster if you cut back and not slam the gears. The nice thing is that while you're fiddling around with the speed settings if you top out and stall the stepper - no harm done. That NEMA 23 won't strip the gears. Just make sure you adjust the backlash as close as you can without binding and keep an eye on it from time to time.

    T-nuts - this is a Chinese rotary table so you probably have metric T-slots. My guess is a M8x12 T-slot, but set your caliper to metric and measure the height, width, and side slots. I just bought some from J.W. Winco - they were considerably cheaper than anywhere else online. An alternative is to mill down a 3/8 if it doesn't quite fit right- but it should go in there a little sloppy.

    3.
    Told you so. Single phase motors are noisy, and you've got that gear set in there screaming away. Your table saw is even louder because it's probably a 3600RPM thing, and your mill motor is turning at half that. Belt-drive and 3 phase motor or brushless DC would be your friend here.

    4.
    That doo-dad is called a drawbar. And at the max RPM you have available, the wobble isn't going to roach your bearings any time soon. It will drive you crazy watching it, however; mine did the same thing.

    What you do is make a new drawbar. McMaster sells 7/16-20 grade 8/9 all-thread and extra-heavy nuts. Pin and lock-tite the nut on the end, and make a big-old pair of bearing plates that are a close fit on the all-thread. Bottom bearing plate gets a shoulder turned to fit inside your spindle with a little clearance so it runs true. Top one is same size as the bottom one OD (spindle OD). Polish the contact faces, harden them with a torch & oil, and re-polish. Add some never-seize to the threads, bearing plates, and collet taper and you'll never have to look at the cheap wobbly drawbar again. And you'll have enough all-thread left over to make a second one when you wear out the first. And use a torque wrench to tighten the drawbar - not a cheater. Or get a cordless impact that can't go higher than about 15ft-lbs if you want a poor-man's power DB.

    -S
     
  11. MontanaAardvark

    MontanaAardvark United States H-M Supporter - Premium Content H-M Supporter-Premium

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    The thing about the rotary table that puzzles me is that I wrote down both decimal inches, and mm, and it doesn't strictly match anything.

    Tee-Slot.jpg

    The width of the slot is 11.0 mm, the bottom width is 17.3mm, wide section height is 7.64mm and the narrow section height is 9.4mm.

    The dimensions look like a 3/8 slot except for the width of the bottom part (0.68). Engineers' references say that should be bigger: 0.719 at minimum. In metric, that slot with of 11 mm is halfway between M8 and M10 at 10 and 12mm, respectively. Otherwise it looks like it would be M8, like you say. Either way, one dimension messes up the match.

    StandardTeeSlots.jpg
    The slot is just a bit tight on 7/16 (.438) which is what I have for the 0704. I can slide one of those nuts in the slot if the nut's upside down, but the bottom slot is too narrow and the bottom section height is too short for the 7/16 Tee-nut.

    I tried some hardware I have and found a 3/8-16 "hardware store" nut fits in width but is too tall for the slot. A 3/8 bolt will fit in the slot, so I'd have threads sticking out instead of a nut in the slot.

    Not that there's anything wrong with that.

    Hoss has a video where he makes an adapter to mount a 6" four-jaw chuck on the table. He made his own Tee nuts. A four jaw might be a good thing to have on the rotary table for almost everything.
     
  12. JimDawson

    JimDawson Global Moderator Staff Member Director

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    I just made T-nuts for mine. A nice couple hour project.:)
     
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  13. spumco

    spumco United States Active Member Active Member

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    That sounds like sloppy M8 slot. The metric T-nuts are so cheap at JW Winco you should just buy some instead of making them. If you try to kludge something in there that isn't an actual T-nut, you could put an angular strain on the slot and possibly crack the slot lip.

    Unless you want to put miles on an end mill just for fun. I actually have to skim about .025" off the bottom of some of my table T-nuts, but that's just a single skim pass off the bottom. You're talking about facing the stock, profiling the shoulders, flipping and facing again, then drilling and tapping before finally cutting to length and deburring. (all that x2 if you want a couple of spares) That's quite bit of work for some stupid nuts that are $2.42 each and can be in your hands in a couple of days.

    As for the chuck - you can fit a 6" chuck on it, but I'd recommend thinking about a 4" or 5" instead. Check your jaw clearance to the table with the proposed 6" chuck and see if it's even possible to hold something that big with the jaws spread out on the OD. In addition, the further you get away from the A axis centerline the less rigid your setup will be. You don't have a brake on your 4th spindle. Ok, you do have two brakes, but what happens when you forget to loosen them before the next move? Or if you're doing 3D contouring with continuous rotation? Any machining offset from the A centerline will have gobs of torque on the 4th axis - and a 3" off-set (6" part) may be a bit much for a rigid setup.

    Finally, how would you even mount the 6" chuck to the backing plate and then mount the backer to the faceplate? At that point you just get a front-mount chuck and be done with it.

    Another thing to consider - get two-piece jaws. That way you can swap between OD and ID without having to rotate the chuck to get clearance for the bottom ones to come out. Another benefit of a smaller chuck is that you may have clearance to pull the bottom jaws without rotating.

    If you want to do something big, make a trunnion table that bolts to the faceplate and is stabilized outboard by a tailstock or something. This will get the part closer to the centerline.

    I'm now seriously considering making another adapter and adding a 3-jaw chuck to the collection. That, or a front-mount chuck. Because of the mounting system it'd be fairly easy to dial it in very concentric (vs. on a lathe where you're sort-of screwed if it isn't true). I got the 4-jaw to hold square stuff, and I like it, but dialing in a part is painful. With only 15RPM available it takes FOREVER to get something running true. My 4th doesn't have the ability to unlock the worm, unlike the expensive grown-up HAAS or other commercial ones. For quicky jobs that don't have to be dead-perfect, a 3-jaw would be an order of magnitude faster.

    I mounted mine using flat head socket screws with conical bearing washers (also from JW Winco) so they sit flush but have a nice big holding surface. Every little bit helps with clearance.

    Backing plate was 7"x7" .875" stock, and I did all the ops from the top side holding on to about .125" of the stock. Flipped it over and ran a profile around the outside before facing off the back parallel to the front. Profile was to avoid having the facemill plow through a bunch of unsupported stock and chatter like mad on the last .010". Counter-sunk the chuck mounting screws (M8 flat head) by hand on the work bench - easier than taking forever to indicate the holes after the flip.

    Things to consider based on my mistakes and having used it a few times now:
    - give yourself enough slop on the backing plate to face plate mounting holes to nudge it true.
    - pick a chuck and bore the mounting plate center hole larger than the chuck hole. Gives you access to the 2 or 3 MT taper in the spindle for all sorts of good reasons. Also think about boring it to some known exact diameter to use as an indicating surface. It doesn't have to be bored with a boring bar - drill a starter hole and hog out the hole with an end mill.
    - keep it as thin as you can without any flex. More clearance is better and less overhang is very nice.

    -S

    IMG_3419.JPG
     
  14. spumco

    spumco United States Active Member Active Member

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  15. MontanaAardvark

    MontanaAardvark United States H-M Supporter - Premium Content H-M Supporter-Premium

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    As usual, lots to absorb here - and thanks for that. I'm not decided on how to setup the rotary table. Not by far. I haven't even verified I'm getting the right number of degrees in a movement or checked it for backlash. To to that, I need to attach something to the table.

    I have both three and four jaw chucks for my LMS lathe, but don't want to tie one up on the rotary table as they're both very useful on the lathe. OTOH, Shars has several nice chucks in the 4" size class, and I could dedicate one of those. I'm sure the same goes for other suppliers. The table has an MT2 taper in it, so that's an option for mounting a chuck. It seems like clamps and Tee nuts are probably the most direct, secure method.

    On my Sherline's rotary table, I have both independent and scrolling four jaw chucks. The scrolling 4-jaw isn't as accurate as the independent jaw, as you'd think, but it's pretty good. Now that I say that, I don't recall the numbers. These are 3" chucks. It's a 4" rotary table.

    Thankfully, I have lots of options. I occurs to me I could upgrade my big lathe to a 5" chuck and use the 4" chuck on the A-axis.

    I'm still working on the bulk of this thread: the tooling plate and tool changer questions. Thanks for the motor/VFD reading on the CNCZone forum to go read.

    I'm also working on a problem on the Sherline mill, so I've been out in the shop trying to shim a gib. It's 10 years old, and the gib is a plastic or composite, so it's probably worth it to just go get a few spares to have around the house. If one is wearing out, there's bound to be another behind it.


    Bob
     

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