Touch Probe Not Accurately Setting Z

I’m using the touch probe to set my zero and it’s not accurately registering. Here’s my process:

  1. Securely attach my material to the wasteboard which has been surfaced by my Shapeoko XL.
  2. Connect CM, initialize my machine and allow the BitSetter to measure the length of the bit.
  3. Place the touch probe at the corner of my material with the edge HANGING OVER.
  4. Jog the bit to above the target and then tap the Probe button in CM.
  5. Choose the three axis zero with the correct bit selected, in this case a 1/8" Endmill.
  6. Probe goes through it’s steps and the zeroes are set.
  7. Run my file and find that my pockets are approximately 0.05" too shallow.
  8. Troubleshoot by zeroing on my material with paper and find that the pockets are the perfect depth.

The photo is the test pocket run after the paper zero. Any thoughts on why this is occurring, and more importantly, how to fix it?

One thing you have to be careful when setting you Z0 is that often, the edge of the board may be damaged or the material is somewhat uneven or the material may not be touching the wasteboard evenly for example clamps may press the material unevenly, some being tighter for example. 0.05 is not a lot so maybe you want to check the Z0 manually in the corner and where you have you pocket to check if there is a difference.

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well if he used the paper method at the same spot as the probe … wouldn’t that be pretty much the same?

(but yes I’ve learned to probe Z in the middle of the wooden material… I had to give up on my probe since it was consistently 0.7mm off)

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Valid point about clamping pressures and the subsequent height of the material. I have this stock brad nailed with 18ga 1" brads in each corner across 19" in width and 13.5" in height. It certainly could effect it by 0.05" as I get away from the corners. On my next iteration, I’ll zero X/Y on the corner and redo the Z in the middle.

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Sometimes, material has a tendency to bow in the middle.

Unfortunately, at least for this troubleshooting exercise, I didn’t redo the zero on the corner. I did it more toward the middle of the material. I’ll zero in the middle on my next iteration.

I’m not going to be happy if the probe ends up being off…seems like it defeats the entire purpose. If it’s material warping or deflection, I can live with that.

I’ve been noticing something similar. I’m trying to figure out a routine that will swap bits and return to 0,0,0 to test this.

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True, and in the end 0.05 is not the end of the world considering the material - MDF. Sometimes I need to take a step back and consider good enough, good enough.

Please contact us at about your Probe not being accurate and we’ll do our best to work through this with you.