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Different live Z adjustment for PETG and Powder coated sheet?  

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nimaim
(@nimaim)
Trusted Member
Different live Z adjustment for PETG and Powder coated sheet?

So I use solely my powder coated sheet to print on because I've gotten superb results with it and never need to "prep" it before printing anything (e.g. glue, windex, etc.). There is the occasional wash with soap and water and pre-applying IPA, but that's it. I've damaged my smooth sheet a bunch already (dimples, scratches, etc.) and haven't had time to apply a new PEI sheet.

Every time I've printed PETG recently, the powder coated sheet has been getting more and more scuffed (with a clear "mark" showing where the print just was after I've removed it), which is curious since PLA does just fine.

Do you guys use a different Z offset for materials like TPU/PETG? If not, how do you get PETG not to screw up the powder coated surface? And yes, I wait until it cools down to room temperature to remove the print and it comes off just fine flexing the sheet, though it never seems to come off "clean". As such, I'm hesitant every time I need to print PETG, as I don't want to further damage it.

I tried to get Prusa support to replace it for me as it seems to be an early model (I know there's been later revs of the PC sheets), but they refuse to, even though I've followed all the recommendations online. I can post a pic later but printing some stuff right now.

This topic was modified 2 years ago by nimaim
Posted : 07/06/2020 8:56 pm
bobstro
(@bobstro)
Illustrious Member
RE: Different live Z adjustment for PETG and Powder coated sheet?

You'll find recommendations to back off Live-Z for PETG anywhere from 0.02-0.2mm. It's not absolutely necessary, but can produce a better 1st layer and reduce the odds of filament sticking to the nozzle. I'll just do a quick adjustment as I watch the 1st layer go down and not bother with elaborate profiles or more rigorous steps.

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Posted : 07/06/2020 9:03 pm
nimaim
(@nimaim)
Trusted Member
Topic starter answered:
RE: Different live Z adjustment for PETG and Powder coated sheet?

Thanks Bob. I've already backed it off 0.25mm (to be on the safe side, these sheets aren't cheap) but that adversely affects print strength / layer bonding as that "squish" between layers is less prominent. This also makes it semi-borderline whether or not it's going to adhere to the plate properly throughout the print. I guess there's a fine line in between but I never heard of PC sheets getting damaged / scuffed like this so I was curious what others were doing.

This post was modified 2 years ago 2 times by nimaim
Posted : 07/06/2020 10:06 pm
nimaim
(@nimaim)
Trusted Member
Topic starter answered:
RE: Different live Z adjustment for PETG and Powder coated sheet?

Anyone else's early PC sheet get damaged with PETG without having to back off Z offset significantly? Not sure I'd call mine damaged per-se as it still works but it's more "marked/scuffed up".

Posted : 08/06/2020 11:49 am
jsw
 jsw
(@jsw)
Famed Member
RE: Different live Z adjustment for PETG and Powder coated sheet?

I have one sheet profile for the smooth sheets and another for the textured (PC) sheet. I do not vary due to material. My current 'textur1' profile works well with PLA and PETg.  I don't ever remember doing ABS on the textured sheet.

I agree that it needs little prep.  IPA is all I've needed.  I've heeded the warning to never use acetone on it.  It sticks with the skirt and first layer quite well, and if I let it cool, it literally falls off.

Posted : 08/06/2020 12:13 pm
nimaim
(@nimaim)
Trusted Member
Topic starter answered:
RE: Different live Z adjustment for PETG and Powder coated sheet?
Posted by: @jsw

I have one sheet profile for the smooth sheets and another for the textured (PC) sheet. I do not vary due to material. My current 'textur1' profile works well with PLA and PETg.  I don't ever remember doing ABS on the textured sheet.

I agree that it needs little prep.  IPA is all I've needed.  I've heeded the warning to never use acetone on it.  It sticks with the skirt and first layer quite well, and if I let it cool, it literally falls off.

And no visible marks / scuffs on your PC sheet? Interesting. I feel like I'll have to set up a diff profile just for PETG / TPU (anything that adheres too well) for this sheet. I backed it off so much I'd say it's probably a 3 sheet of paper gap now rather than the 1 that works great with PLA. It's likely that once the main layer was scuffed up, it's now compromised for each subsequent print.

Posted : 08/06/2020 12:26 pm
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