Permantly adjust Z axis?
Hello all,
Since I got my mk4, I have had adhesion issues. I started with a smooth sheet, bad adhesion, I wound up glue sticking after trying all the standard advice (wash it with water and a little dawn, wipe it down with IPA, etc etc). Glue sticks worked more or less OK although I am pretty sure I shouldn't be needing to do that. I got a satin sheet, and it was the same thing: bad adhesion even when fresh from the factory, washing it with water and dawn didn't work, IPA didn't work, glue sticks it was.
I finally assembled my MMU3 and got a shiny new textured sheet, exact same issue, but worse: not only was the adhesion bad but I could tell the first later was a little bit too high. I used hairspray and that worked more or less OK. Finally I read about adjusting the live Z and that, finally, seems to be perfect: I reduced my live Z by -0.002 and I am seeing a clear improvement. I don't think I'll ever get that "petg is hard to remove from the bed" that people seem to have, mine basically falls off even with hair spray - but good enough.
I am tired of setting that z every single print, how do I do it permanently? There is a slicer setting somewhere, I bet.
Also, is -0.004 or 5 too aggressive? I am hesitant for fear of damaging my sheets or nozzles.
Best Answer by UjinDesign:
Hello! I don't know the inner workings of how the printer determines the proper z-height when probing. Maybe something is off hardware-wise with your printer, and if I were you I'd ask the Prusa support chat real quick.
Yes, there is a way to permanently adjust the z-offset. Just go into the Printer settings, make sure you've enabled either "Normal mode" or "Expert mode" in your slicer (see top right of the screenshot) to show more options. Change the "z offset" settings. Save the new settings as a new printer, and select that printer when doing future slicing. I personally did exactly this but raising the z offset a little when printing with PETG, because I found that it helps against filament creeping up on the nozzle on the first layer.
It sucks to damage a print sheet, so if you're unsure how much of a z offset is reasonable before damaging your sheets, just pick the same value you're using when you do your live z offset testing, right? (I haven't done that personally so I don't know if that's a fool-proof way, but it seems like it). Just thinking logically I'd say that the most you can decrease your z offset before you run into the risk of damaging your print plate would be if you lower it more than your first layer height (usually around 0.20 mm for 0.4n).
RE:
Hello! I don't know the inner workings of how the printer determines the proper z-height when probing. Maybe something is off hardware-wise with your printer, and if I were you I'd ask the Prusa support chat real quick.
Yes, there is a way to permanently adjust the z-offset. Just go into the Printer settings, make sure you've enabled either "Normal mode" or "Expert mode" in your slicer (see top right of the screenshot) to show more options. Change the "z offset" settings. Save the new settings as a new printer, and select that printer when doing future slicing. I personally did exactly this but raising the z offset a little when printing with PETG, because I found that it helps against filament creeping up on the nozzle on the first layer.
It sucks to damage a print sheet, so if you're unsure how much of a z offset is reasonable before damaging your sheets, just pick the same value you're using when you do your live z offset testing, right? (I haven't done that personally so I don't know if that's a fool-proof way, but it seems like it). Just thinking logically I'd say that the most you can decrease your z offset before you run into the risk of damaging your print plate would be if you lower it more than your first layer height (usually around 0.20 mm for 0.4n).
RE: Permantly adjust Z axis?
OK, easy enough - thank you! I appreciate it.
RE: Permantly adjust Z axis?
Also, is -0.004 or 5 too aggressive?
0.004 is basically nothing. On my Mk4S I have to adjust Live Z by about -0.03 to get a good first layer. For PETG that is. With PLA, I need to adjust it by +0.03 to avoid ripples. SO much for the "always perfect first layer". While it was a bit time consuming to dial a Mk3S in, at least it never needed any adjustments after that. The load cell based Prusas are in a different league—and not a better one. Plenty of reports on their GitHub site, and Prusa shrugs it off as "cosmetic".
Formerly known on this forum as @fuchsr -- https://foxrun3d.com/