Hi Graham, Thank you for sharing your expertise. I'm still learning, and very grateful for your help. I have a 3d spindle probe that I use as my G31 probe. I have a small tool setter that I use as my G31.1 probe for setting my tool offsets that is .76" high. So that I am understanding you, your reference to the "spindle end face", I believe that is the spindle gage line. When I did the probe Calibration routines, tool #1 shows a tool length that was put there following the Calibrate Z as the final probe calibration process. My tool gage setter, which is nothing more than a round touch-off with an alligator lead I attach to the tool. This touch-off plate is .76" high which is what I used as the guage block height when I set each tool using the G31.1 probe signal. One thing that I didn't do when setting the Calibrate Z, I didn't use the .76 as an offset for the probe. However, when setting the default tool, I left the default tool Z setting at height offset at 0 and then used the .76" gage block height offset while setting each tool. Did I do this correctly? I'm sorry, I hope I'm making sense in my questions. I'm trying to reconcile all these offsets in my mind, and I think I almost have them figured out. At least I hope I am. Again, thank you for your help.