Tool Setter Position on machines without persistent absolute positioning

[mark0815]

I have a CNC mill with a tool setter mounted on the table.
As my mill does not have an absolute encoder (neither glas scales nor rotary encoder)
I have to probe the precise Z location of the tripping point of the tool setter after each homing of the machine.

I added such a feature in a fork of probe_basic some time ago but then switched back to axis for other reasons.
My approach was:

• Take the (rough) position of the tool setter from the configuration
• Probe the tool setter with the spindle nose
  • Remove any tool
  • offset x by spindle_nose_diameter/2 to hit the tool setter with the ring of the spindle
• Calculate a new value for "spindle_zero_height" based on the tool setter tripping point.

Is such a feature of value? If so I would like to integrate the changes into the current code base and create a PR.

Regards
Mark