I’m testing the accuracy of the Z travel and am very slowly making progress getting it dialed in but is getting out of hand as far as changing the z value on my probe…
I’m making a .125" pocket and am consistently cutting deeper, by around 16 thou. Every time I adjust my dimension for the probe to account for the change it makes very little difference in the outcome, usually increments of 2 thou. At this point I’m entering 13.xx mm for the probe (even though my calipers are showing 15mm+.
Also the fact that it’s always in mm and not imperial is making me add an extra step in conversion which is annoying. Is this jus the way it is? Yes all of my settings are in imperial.
Are you using wood as the carving medium? Wood is surprisingly elastic at these tolerances; between spring-back, moisture absorption or loss, wood fibers that lay over rather than actually being cut, etc. I’m not sure you can get dialed in a whole lot closer. Also double check that your z carriage is fully and evenly tightened. You might want do use a different material - aluminum, or even hdpe.
Have you compared the probe method for Z zero with the paper method? They should give your close to the same value for Z zero. By the way, 1mm is about 40 thou. Way more than your discrepancy.
I would think it extremely rare, but I suppose there could be a flaw in the z ball screw. Have you tried elevating or lowering the surface from which you reference to use another portion of the screw threads?
Just had another thought…in your Settings–>Probe Dimensions–>Probe Fast Seek (and) Probe Slow Seek…
My default settings are 75 mm/m fast and 25 mm/m slow. You might try temporarily setting those to ridiculously slow (like 10 and 5 mm/m) and see if that makes a difference. If so, there could be an issue with your CPU in the controller or even the Z stepper motor - computers are fast, but they are not instantaneous; it does take some clock cycles to determine that the probe circuit has now closed and thus it’s time to stop the stepper motor…if the CPU is occupied or having an issue, it could be failing to react quickly enough…
One suggestion I might make on resetting the probe thickness value - after you set it restart the controller… Not sure how you’re interfacing with the Onefinity but if I make changes from a remote computer they aren’t reflected on the locally attached touchscreen.
One other thought would be your workholding, when using an upcut bit, cutting forces want to lift your material up which could be resulting in a somewhat deeper than expected cut although I don’t think it would be the full .016" you’re seeing.
That tells you it’s not a probe problem. Next check the z axis calibration (using probe or paper) with some references of known thicknesses. Need to rule out z axis hardware.