Add additional height for the first layer. (in custom G-Code)
At least one of the print surfaces I have, tends to require 0.15mm extra height for TPU not to flex too much, and trigger the rotation sensor.
I guess, that perticular surface does some significant thermal expansion.
On other beds/filaments, the BLTouch height is perfect.
My "Start G-code" contain G28 and G29 - I can guess that I could add a Z-travel command of +0.15 that is not "counted" after G29 - and just uncomment that line when this kind of print surface is used.
I wish for the command to just offset everything, so that it works for sequential printing too.
I do not wish to use M851 , because that is absolute, then I need first to see what offset a printer already has, and modify it. It would rather like a relative move that the machine did not "count" (being at 0.3mm over bed, it moved up 0.15mm, but still regarded the position as 0.3 - so it would work for sequencial prints.)
RE: Add additional height for the first layer. (in custom G-Code)
Sorry, I must be missing something in what you're trying to accomplish but why not just set first layer height to whatever you want it to be? Maybe you want to add the offset to filament custom gcode but if I understand correctly what's happening, it happens only on a specific print surface so you'd have to make manual changes anyway when you print on that surface as the slicer has no way of knowing what surface you're printing on.
Formerly known on this forum as @fuchsr -- until all hell broke loose with the forum software...
RE: Add additional height for the first layer. (in custom G-Code)
what is correct Z offset works for most build surfaces.
One or two build surfaces, I assume expend too much, and make TPU compress too much in the bowden tube , making the filament sensor rotate "too little" as if there was a jam.
What I try to accomplish is NOT to mess with M851, but have a line I can uncomment in the start of some jobs - that rises the nozzle additional 0.15mm