Using the Mitutoyo 950-111 Zero Setter and Haimer probe (other probes would likely work). After calibrating the zero setter and placing it on a clean reliable surface (back of vise works good) load your probe and don’t forget to set your T# to the appropriate offset (I’m using 50 for my Haimer). I have been using work offset G59.3 for all tool setting. Bring the probe down on the gauge block side of the setter until the probe is zeroed. Zero your Z on the DRO.
No documentation comes with the Zero Setter, but this is how I figured it was intended to be calibrated. If you really need (i.e. OCD) the needle to be in a certain position when it is at zero, there is a set screw holding the indicator into the assembly that would allow changing the relative position of the hand.
change to the desired tool and bring it down on the pad side of the setter until the setter reads zero. Make sure to tell your control what number tool you have in and click on the “M6 G43” button. The Z dro will now read the length of your tool from spindle nose (assuming you set your Haimer per Tormach’s directions). When you type or copy and paste the value in the length column, the Z on the DRO should read 0.0000. No math required. This works extremely well for replacing broken or dull tools mid run as well. I clean off my vise, change to G59.3 and establish the new cutters offset as above, then switch back to G54 and run m program.