Clough42-based ELS for the G0709

[mcdanlj]

I just completed a Clough42 ELS install on my G0709. Thought I'd quickly share lessons learned:

• The gearbox is stiff. I couldn't drive it 1:1 with a 180W servo. I'm driving it 6:1 with a 3d-printed 11-tooth 1.5 module gear on the servo (seems to damp vibrations better than metal, so planning on it being a wear part I replace occasionally rather than cutting a permanent one in metal). I think if I were starting from scratch with what I know now, I would splurge and get the substantially more powerful 750W iSV2-80TR-48V750A to drive the gearbox. Or if I wanted a bigger project, just replace the whole gearbox.
• James's firmware doesn't support all the threads that the gearbox provides, even ignoring mod/diametral pitches. I wrote a PR for James which adds a digit of precision and optionally adds more threads (all the ones on the G0709 except for mod/diametral) which makes it a straight superset of what's supported on the G0709 for threads, anyway.
• I also merged that PR with Steve Ward's thread-to-shoulder, angular position reporting, and arbitrary metric thread spec PR.
• Here's the firmware I'm running — it is set up for 6:1 driving ASW1 with a servo set for 168 steps/rev, but you can use my Characterizing the G0709 quick change gearbox post to choose a different ratio.
• You can't use a stepper and get precise threads through the gearbox, as far as I can tell. Need to use a servo and choose a number of steps per motor revolution that gives you an integer steps per lead screw result. My PR has a Python one-liner to help find those.
• The firmware doesn't know that Z and X feed rates are different. Mine is set up for Z, and just know that X is about ¼ of Z.

If you want all this in the form of a story, I posted it at Maker Forums. ☺

Hope that's useful to someone someday.

 

[wachuko]

That was brave… I do not have the courage nor skill to do that with mine!!

Have you done any videos using it?

 

[mcdanlj]

@wachuko The only irreversible change I made to the lathe was drilling another hole for the wires from the primary control enclosure to my secondary enclosure. Everything else I could just pull off and replace with the original change gear set. That reduces the need for bravery. Bravery would, I think, be actually to replace the entire transmission with an ELS and stop turning a large set of gears more or less uselessly. ☺

What would I put in a video? I guess I could shoot a video of threading to a shoulder? But other than that, the whole point is that it works about the same, but without having to mess about with change gears and transmission knobs that you have to fiddle the chuck to get to change half the time, and with additional pitches available?

I'm not much of a youtuber...