Gcode - Input custom number

Hi all.
I searched the forum and the net for some hint, but I didn't find anything usefull to me.
All the topics/hints I found were related to people who need to pause the executing gcode, be asked for a value then resume the job.
Basically, my need is similar (thinking about), but not sure.
My issue:
Normally I use a touch plate for Z.
In these days I realized an aluminium set square (90°) to zeroing Z-Y-X (in this sequence).
The thing works fine, but....
My intention is to fasten the square on the work plane, then use its hollow to place the corner of the material (the 0;0 piece), then zeroing the axis for the job.
But at this point I have the issue of the material thickness.....
My current zero gcode set the square thickness (15mm) as offset, and it works fine: when I type G0 Z0, the bit touch the work plane properly.
But in a "real" job, the Z offset should be "15 - material thickness".
I thought about make some custom buttons in Axis for the my known standard thickness (1.6 for PCB, 1-3-5-6-10 for acrylic).
But doing so I'll have to set 6 buttons and 6 NC files to call each time, instead of just one but asking me the material thickness before starting zeroing.

So, can this be done?

Thank you

Andrea

You can use a hal flied to enter the value an d then a button to trigger the g code:

G10 L20 P0 Z[#<_hal[name.of.hallable]>-15]

Thankyou for the suggestion,i'll give it a chance.

We had a similar requirement. We ended up defining a custom M code to prompt the user for a value and set a HAL value:

github.com/fortcollinscreatorhub/cnc/blo...nuxcnc/nc_files/M101

Then in our probing script, we read that value:

github.com/fortcollinscreatorhub/cnc/blo...cnc/nc_files/103.ngc