I can’t get my probing offset working. I’ve tried a few varfious tidbits in this thread. When it touches the plate, my Z is 0.5. Using M851 has no effect. I’ve tried with and without USE_PROBE_FOR_Z_HOMING commented out.
Also, can’t get any result from
#define Z_PROBE_END_SCRIPT "G92 Z14.25\nG0 Z18 F6000\n"
No movement ever happens.
Okay, it’s the TFT and the firmware.
G28 Z respects/uses the offset properly.
“Home Z” on the TFT does not seem to work properly. 
AHA!
The TFT firmware stores touchplateThickness in a parameter which can’t be edited. It is set to 0.5. So the issue lies in the TFT firmware.
Back to manually setting Z 
1 Like
I believe that people do this with the custom menu in Marlin. They set up the “home Z” script as follows:
; set relative coordinates
G91
; home Z to the touchplate
G28 Z
; Set the workspace coordinates to the top of the touchplate
G92 Z3.09
; lift the spindle 5mm
G00 Z5
; set absolute coordinates
G90
Should this work for x and y too?
Then i can use some cornerpiece aluminium as positive and bit as negative so i always have the exact corner and height set gcode in custom menu