Jumping, thumping, burning

I’m doing cutouts using .19" pine luan. I switched from an 1/8th to 1/16th inch end mill (feed: 30, plunge: 20, rpm 21000, depth per cut .28.

I’m having a couple of issues.

  1. During the cutting the machine is staggering/stuttering (that’s the best way I can describe it).
  2. Portions of the cut are burning
  3. The machine went off the original toolpath and cut a shape out about 4 inches to the left of where it had originally been programmed to do so.

I’m still new and learning so any advice on what I might be messing up would be appreciated. I did manage to do several cutouts with that bit on those settings successfully before suddenly running into this issue.

Thank you! -Aaron

Please check your endmill (for sharpness) and your feeds and speeds (for appropriateness to the material and machine — see http://www.precisebits.com/tutorials/calibrating_feeds_n_speeds.htm )

Please check the machine mechanically as per: http://docs.carbide3d.com/general-faq/machine-operating-checklist/ and esp.:

You may want to calibrate per: http://docs.carbide3d.com/shapeoko-faq/how-to-calibrate-the-machine-for-belt-stretch/

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Thanks for the helpful links. I adjusted my numbers and tightened the belts and it ran super smooth. Thank you! -Aaron


In case other folks come across the thread what numbers worked better for you? I recently did some baltic birch cutting and based on GWizard kept it at .1" depth of cut, though I ran it a bit faster at 50ipm.

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Dan, good thought. I adjusted the feed to 40 and plunge to 25. I also changed the depth per cut from .28 to .14. I also tightened the Y axis belts as they seemed a little loose to me. I’m not sure which adjustment did the trick but its humming along wonderfully now. I’ve attached a pic of the project. IMG_1531