electronic lead screw

kb58 said:
<snip>
I guess what I'm saying is that if you want to build one now, you can without needing to wait on anything.
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That's what I gathered from Github.

Pictures of what you've done?
 
well... sort of. Matching the driver boards to the steppers, and to the logic board isn't a slam dunk. In the sense that you can buy and entire kit from Rocketronics, it makes the procurement part a one-stop-shop. The Clough42 solution would be a LOT cheaper, but I just don't want the uncertainty of doing it myself. I'm not really worried about reliability and fixing: the Rocket solution has a very good rep, and good customer service.

I'm not totally decided yet, but at the moment I'm leaning that way. If the Clough42 option seems more like what I'm okay with, then I'll probably go that way instead. I've got time to wait and see how things fall out.
 
matthewsx said:
That's what I gathered from Github.

Pictures of what you've done?
Click to expand...

IMG_20191020_173340.jpg
 
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Dabbler said:
well... sort of. Matching the driver boards to the steppers, and to the logic board isn't a slam dunk. In the sense that you can buy and entire kit from Rocketronics, it makes the procurement part a one-stop-shop. The Clough42 solution would be a LOT cheaper, but I just don't want the uncertainty of doing it myself. I'm not really worried about reliability and fixing: the Rocket solution has a very good rep, and good customer service.

I'm not totally decided yet, but at the moment I'm leaning that way. If the Clough42 option seems more like what I'm okay with, then I'll probably go that way instead. I've got time to wait and see how things fall out.
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I probably have about $350 into the Clough42 build end-to-end, with about $300 of that being the pulleys, belts, servo, driver, encoder and power supply. Those costs will have to be added on to the Rocketronics unit as well, so it does add up.
 
Briney Eye said:
You found me. I don't have any backlash compensation because it's not CNC, just a programmable "gearbox". The number of pitch selections is arbitrary. I've implemented every pitch that I could find in online pictures of lathes, and every tap available from McMaster-Carr. I stopped short of having an arbitrary programmable option, but it would be possible. I did limit it to 4tpi just because I have a small lathe. That's getting to be some serious depth of cut, and I have already noticed some "hiccups" cutting an 8tpi Acme thread in 1144. I'm waiting for more timing pulleys and belts so that I can gear it down from the current 4:1 ratio between the stepper and the screw. I'm planning to test it at 5-, 6- and 8-to-1.

I still have more to do. The touch screen is great for a lot of things, but on-the-fly feed direction control needed something more tactile, so I've added a toggle switch mounted in front of the headstock. I quickly programmed it to control the direction, but have to add jogging support still. I just got sidetracked by actually making some things.

I think it would be cool to do cut knurling, so I'm also thinking of adding support for multi-start threads, but that's a ways off yet. I've only used half the RAM on the Mega so far, so there's still room to squeeze more features in :). I promise to make at least a basic version of the code available at some point when I'm satisfied with it.

-Jon
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wow thanks Jon, glad to "meet". Thanks for the detailed reply - it takes time to draft something logically, so appreciate your time spent very much. EXCELLENT work & love the tidy background shots of your shop! (You are not gunna see mine!! - yet).
yeah funny how work gets in the way of research/fun.
I have reviewed a few ELS designs on youtube:
1. Rocketronics.de, Germany,
a turnkey product, not arduino related AFAIK, he does use an Atmel, very pricey (converting to Aussie dollar plus freight. He drives the X axis as well, so the thread cutting process is looped, down to the finish cut.. more to contemplate for you?! Your display is far more user friendly.
[I cant see the point of designing something that makes U feel all technophobic- which happens regularly here].

2. Clough42
He uses a heavy duty TI MCU with on board hardware handling of encoders to avoid excessive interrupts, & a floating point processor-> not sure of that animal at all. He claims only a 1/10thou threading error after running lathe for 15 min.!! (dunno where the error relates back to, i think its in the math cycle inside his Ouiji board beast). No X axis drive, 7 segment Leds & buttons display only.
- Any Threading errors occuring for you, Jon?

3. https://www.wadeodesign.com/cnc-lathe-documentation.html
"I've been a Mechanical Engineer for about 25 years and have always liked the challenges and rewards of creating solutions to problems. My interests in building as a hobby originated from working with my Father in his wood shop where he built every piece of furniture the family ever owned and has a passion for building diy style". Heartwarming, a dedicated man indeed :)
This guy has also been thorough, highly detailed doc'n (B.O.M with links to suppliers, costings) & vids, using a Grizzly 10x22 bench top lathe, threw away the guts of the gearbox & put the stepper in there, avoiding stepper overhang at the other end. X axis 'Clearpath' servo is behind lathe not on the apron. A half-nut microswitch is used. The X axis handwheel does jut out more to accomodate the AMV-102 settable capacative low cost encoder.
The Z axis handwheel remained in situ!
- his youtube clip shows a simple display but with surprising functionality, including 3 memory settings. His concept is to have the lathe used in manual mode, standalone arduino controlled ELS, but then switchable to Mach4 for full CNC.
With x axis powered, threading is looped too..
He uses 2 encoders on Z & X axis which enables a DRO function on the same "simple" screen! His arduino must be doing overtime,, no mention of any threading errors, .. [so maybe Clough42 an overkill?]
.. Starting to get hard to remember who done what!
- so much talent out there, makes me wonder whats next.
Your colour touch LCD display is a real drawcard, but agree that messing with a touchscreen in the middle of a cut is a bit dicey, cant beat a switch to grab a hold of. Sounds like all threads catered for.. gas / plumbing threads?

The addition of the X axis would be a real drawcard . In no way am I down playing your efforts here! not sure what U meant by 8 TPI hiccups but i presume it wasnt pretty.. But am sure u can fix it.
Yep knurling a great idea, Jon.
No point in releasing anything unless you are happy - will gladly wait. (My old Taiwanese lathe rattles like crazy with the backgears - i hate cutting threads for fear of the neighbours. The metric 127 gear has lost its mate, so cant cut metric ATM).

Getting an Arduino to do anything is a sheer fluke for this 64 yr old 'newbie' - analogue electronics is far more familiar here.
another aspect of a concept i have, is to drive the spindle from a stepper, with angular displacement control/readout, so as to cut long spirals or splines/flutes with a toolpost mounted router - woodwork stuff:)
Incidentally I bought a TI Launchpad & built the Touch DRO. I decided to 'bury' it in thickish aluminium, making it military almost, & sprayed it a bronze colour after seeing Ian on "Full custom garage" spray a car in similar. But i had trouble getting the display to read properly with the cheap chinese scales. No issues with the 'proper' Igageing Easy-View scales. Yuri couldn't help here.

Cheers, QTRON.
 
My shop looks tidy only because of careful framing. It's a wreck, and I barely have room to turn around, which is why I planned to build a detached shop this year about three times the size, but it's looking more like a spring thing all the time.

I'm sticking with the "programmable gearbox" concept for the foreseeable future. No CNC for me, thank you. I still might look at a micro with quadrature decoding at some point. I have no need for floating point the way I'm doing things. I have interpolation error but no accumulation of rounding error, and I can stop at a limit on the same count all day long, better than I can measure with a tenth indicator.

I gave very serious consideration to the Clearpath servos, but cheaped out. The "hiccups" I'm seeing are momentary stalls on heavy cuts that aren't quite big enough to cause my microstepper driver to error out. I think I can fix it by increasing the gear ratio between the motor and lead screw. I'm currently running 4:1, but have ordered timing pulleys and belts that will allow me to test 5-, 6- and 8-to-one. If that's still not enough, I might start thinking about Clearpath again. They have one that ought to be a drop-in, and would double the torque. I just balk at the price tag.

I've been reasonably happy with my TouchDRO setups. I'm using Shars scales with added decoupling caps in the heads to make them more stable. I have the cross feed scale on the lathe mounted above the screw, covered and completely out of the way, and I would have a hell of a time doing that with any other kind of scale. About the only possibility would be a DroPros magnetic scale. I wish Yuriy would get fired up and fix a few things, but he seems to have moved on.

Take care.
 
Dabbler said:
well... sort of. Matching the driver boards to the steppers, and to the logic board isn't a slam dunk. In the sense that you can buy and entire kit from Rocketronics, it makes the procurement part a one-stop-shop. The Clough42 solution would be a LOT cheaper, but I just don't want the uncertainty of doing it myself. I'm not really worried about reliability and fixing: the Rocket solution has a very good rep, and good customer service.

I'm not totally decided yet, but at the moment I'm leaning that way. If the Clough42 option seems more like what I'm okay with, then I'll probably go that way instead. I've got time to wait and see how things fall out.
Click to expand...
I would be interested in your comments, Dabbler, on my comparisons, summary, presented to Jon, Briney Eye re ELS, in particular Wade'O design's efforts, scope of ELS stand alone part of his design. BTW thanks for your comment re Rocketronics good customer service.
Another excellent DRO supplier from Germany is Caliper2pc, https://www.caliper2pc.de/en_index.html, a pc based DRO that can be used in conjunction with Mach3. Has some clever 'wizards' too. Uses Chinese scales, definitely a better investment than TouchDRO.
 
Yay! My HTD pulleys and belt arrived. Guess I know what I’ll be doing tomorrow then. :)
97569402-E29E-4C1A-9972-EAE25A7E5922.jpeg
 
I missed the board, hopefully he'll get more soon. What pulley sizes are you going with?
 
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