Hey guys, I just wanted to share the procedure I use to precisely calibrate my Z axis.
All you’ll need is a Z probe and a metal block of known dimension. I use Universal Gcode Sender for this.
Lower your bit to just above your Z probe. Use the probe command (example: G38.2 Z-5 F1) to probe down to your Z-probe. In my case, I use precision ground, hardened steel “1-2-3” blocks.
Without raising the bit, reset the Z axis zero by hitting the Z0 button in UGS.
Now, raise the bit a little higher than the height of your known object. Place the known object on top of your Z probe block. Again, I use a precise 1-2-3 block here.
In UGS, repeat the probe command from earlier. Once the machine shops, read the current Z postion from UGS.
Now, send $$ in UGS to get the current configuration. In particular, we are looking for the value of $102. In my case, it was set to 49.909.
Now, I use a Z steps calculator to calculate your corrected Z steps value. In my case, my known distance is exactly 3 inches. The distance my machine thinks it moved was 2.990 inches. The calculator returns a corrected steps/mm value of 49.743.
Back in UGS, send the corrected value as $102 = XX.XXX
Repeat this procedure to test your new value.