Carving depth unexpectedly increasing


We’re build a model to cut a 3.1mm MDF board (
Everything started fine, but the X-Carve increased progressively the milling depth : in first path, from 1mm in the first “line”, it arrived to close to 9mm in the last line (still on first path).
Fortunately nothing was damage except the spare protecting board: it’s received the unexpected extra depth.

Anyone has an idea on fixing this issue ?
Does it come from model or from transformation ?
Is there a way to view the generated GCode to verify it ?

Just a couple ideas for common Z axis problems:

-If your collet wasn’t tight enough, upcut bits will tend to pull themselves out of the collet and dig deeper into the wood.
-Your wasteboard may not be level to the X and/or Y axis, although 8mm is a rather dramatic offset.
-If you have a 24V spindle from the first batch, it may be starting to fail.
-If the shielding on your Z axis isn’t grounded and is running next to a “noisy” wire (such as 110VAC), it may be causing it to shift down.

If you’re willing to do so, try to run the program again (with your hand on the e-stop). Watch the Z belt and see if it moves during the operation, and if so, whether it’s in consistent slow steps or sudden jerks of varying size.

I had an issue with the Z cutting deeper as the job progressed. I found two things that resolved the problem.

  1. I cleaned the area that the z axis threaded delrin nut slides up and down on.
  2. (The real cause) the power going to the z stepper was too low. It would plunge correctly but every now and then it would not raise all the way. Consequently the next plunge was still correct in travel but it started lower because it had not fully retracted from the previous up command.

Starting at z 0
Command plunge .25 inches… result z is now at -.25.
Command raise .25 inches… result z is now at -.01 due to low power
Command plunge .25 inches… result z is not at -.26 due to previous command not moving all the way back to z 0 as commanded.

This type of error grows over time. Added power and cleaned debris… no more error.

Hope this helps

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