Well in my machine plan for Z check,
is I have a resistance pressure sensor.
SIMILAR to this one
https://www.sparkfun.com/products/8713
When a juki nozzle is about 10% compressed, the resistance falls from 10M ohms to about 40k.
at 50% compression about 10k.
I'll stick that on the table at z=0;
On spring collar release for the nozzle changed, I need about 700 grams to reliably compress it sufficiently .
glen