I want to make two of something and have two pieces of stock with a little different size that I will be surfacing to the right thickness as a first step. Using zero at the top means bottom values change. I can use the “t” parameter in the measurements by setting bottom to something like “t - 12” mm., but I was thinking the right way to do this is make zero be the top of the wasteboard. Changing the material thickness then would only change how much waste comes off the top in the first step. However, how do you use Bitzero? To get the Z value it needs to be used BEFORE work-holding, but then there is no corner of the stock to align the X and Y. And Bitzero won’t sit flat on the wasteboard because there is no X edge within scope for it to hang over.
What is best for zeroing with zero bottom?
And with zero bottom, the toolpath start depth becomes the thickness. I can use “t” for this, but will the machine start the process before touching the material? Or should I pad the top value a little like “t + 1” mm?
Set up the job for the origin at the Bottom of the stock and set the origin there (somewhere off to the side, or before clamping the stock in place)
set zero at the top of the stock in the file, set zero at the surface of the wasteboard, then jog up to the defined Stock Thickness and re-set zero at that height
set zero at the top of the stock in the file, jog down as it to set zero at the surface of the wasteboard, then enter the Stock Thickness and set the zero at that height as an offset from the current position
You are correct about putting the overhang on the BitZero on top of the material when only probing Z. You hang the overhang over the edge only when probing X Y and Z.