Z-height for zero material thickness appears wrong

[fritzw]

Copied conversation from pull request:

jadatkins commented 38 minutes ago
In your code comments you state that the correct Z value for a material of thickness 0 is 17, but you also say that empirically you found it to be closer to 19. What made you think it was 17? When I perform a "score" using xTool Creative Space and set the material as 3mm basswood plywood, in Wireshark I can see that it is setting a Z height of 17. This makes me think that the value for a material of thickness 0 would be 20. Is it possible you got mixed up somehow?

fritzw commented 28 minutes ago
I thought, that the G-code from the XCS software was cutting at Z=17 for a material thickness of zero, that's where I got this value from. Also, the maximum material thickness I can set in XCS is 16. However, i may have made a mistake somewhere (seems likely, since the focus was that far off for me).

jadatkins commented 23 minutes ago
Here's a capture I made scoring a short line on 3mm plywood. The Z value of 17 is set at the start when all the other defaults are set, and then it doesn't get set again.

https://lightburn.fider.io/posts/2086/xtool-m1-support

[fritzw]

I'll do a few tests in XCS with different material thicknesses tomorrow.

[fritzw]

So, tomorrow turned into "next month", but anyways... xTool Creative Space outputs G1 Z17 for Thickness=0mm, G1 Z14 for T=3mm, and G1 Z7 for T=10mm.

Still, that does not explain why the focus point of my M1 appears to be about 2 mm lower than what XCS assumes. Maybe my measurements of focus were off. I recently got a good mobile phone microscope lens, so I could re-test focus in more detail.

[gsrunion]

Or it could be that XTool is just plain wrong.