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X moves half the distance despite identical settings. <resolved, Lathe is in diameter mode>

Posted: Thu Jul 09, 2020 9:21 pm
by Colt4587
Hello!

So I have a new mini lathe that I have setup with centroid acorn.

I have the Z and X axis setup identically. But the X axis will move half the distance I tell it to via the MDI. If I say X-20 (mm) it will move 10, 10 will move 5 etc. Z axis, with exact same settings, will move the proper amount precisely.

Both axis use the exact same 1204 ball screw

same exact drivers : https://www.omc-stepperonline.com/digit ... m556t.html

Same motors: https://www.automationtechnologiesinc.c ... 570-oz-in/

same exact DIP switch settings:
DIP switch.PNG
same exact software settings.
wizard view.PNG

Yet they do not move the same distance when commanded to using the Centroid Acorn. I have re-done the wiring, re-flipped the DIP switches, even changed microstepping (from 1/8 to 1/16). I also swapped the cables at the plug end, and the cables on the drivers themselves, and it follows the X axis. I have purchased a new driver and replaced each drive with it, and it follows the X axis. I have manually measured the ball screws, and that they do indeed move 4mm per revolution. I've been through all the options in the wizard, but the only way I can get the X axis to move the correct amount is to double the steps per revolution. The only thing (that I can think of) that I haven't tried yet, is to use the screw terminals temporarily to see if they exhibit the same behavior. Right now I am using the DB25.

Report attached, please let me know if I missed anything.

Thank you so much!

Re: Extremely Odd, X moves half the distance despite identical settings.

Posted: Thu Jul 09, 2020 9:57 pm
by cncsnw
X axis movement on a lathe represents changes in part diameter.

For example, if you want the tool to cut a diameter that is 20mm smaller, then you program an X position that is 20mm smaller, and the cross-slide moves 10mm towards centerline (therefore cutting 10mm per side, making the part 20mm smaller).

So it is correct and expected that the X axis, in general, moves half as far as the number you give it.

Re: Extremely Odd, X moves half the distance despite identical settings.

Posted: Thu Jul 09, 2020 11:01 pm
by Colt4587
cncsnw wrote: Thu Jul 09, 2020 9:57 pm X axis movement on a lathe represents changes in part diameter.

For example, if you want the tool to cut a diameter that is 20mm smaller, then you program an X position that is 20mm smaller, and the cross-slide moves 10mm towards centerline (therefore cutting 10mm per side, making the part 20mm smaller).

So it is correct and expected that the X axis, in general, moves half as far as the number you give it.
Welp. That makes total sense, but also totally in line with my "noobness."

Thank you for taking the time to explain that to me.

And at least I've now quadruple checked everything, lol