SO3: Skipping steps? [SOLVED]

I’m not actually sure if that’s what’s happening here, but I’m seeing it with both HDPE and Plywood…I assume I’d see it with other materials, but that’s all I’ve been cutting so far.

Hard to tell if it’s in a certain direction only (X,Y) or if it’s only happening on arcs, but you can see how most of the larger circular cuts here have chunks either missing or left behind from the spindle jerking around.

I was running with a .125" endmill at .0625" stepdown, 60ipm feed, 20ipm plunge.

I’ve checked all of my connections, and nothing seems loose.

Any other ideas?

Check your belt tension and pulley set screws.

I’ve found that more belt tension than is prescribed is needed.

Hmmm. Original SO3 instructions don’t seem to apply to the XXL…there’s almost no play in the motor mounts, so I can’t use that to tighten the belts…am I missing something?

If you’re out of adjustment w/ the new belt anchors, my suggestion would be:

  • loosen the belts at the ends
  • loosen the motor and tilt it forward slightly
  • secure the belts at the end, pulling as tight as you can manage
  • tighten the motor, straightening it up
  • tighten the belts from the end

If that doesn’t help, contact

That seems to have done the trick. Thanks, Will.