Magnetic bed sheet pitting- Prusa I3 mk3s
Hi, during a print recently using PETG I noticed that there are small pits in the sheet around the circumference of the object that was made previously. Has anyone encountered this and can shed some light on what I may be doing incorrectly? The pits seem to be a little worse going around corners. The prints are coming out awesome given this issue. Thanks in advance for your help!
RE: Magnetic bed sheet pitting- Prusa I3 mk3s
What temperature was the bed on that object? And how hard was it to remove?
You are using the Smooth PEI sheet. It is a sticker on a smooth steel plate. Sometimes the sticker gets bubbles...
RE: Magnetic bed sheet pitting- Prusa I3 mk3s
Those are probably not pits, but bubbles in the layer of adhesive between the PEI and the steel. They form due to the force from the part attempting to curl at the edges and pulling the sheet up while hot. If they are bubbles, they will mostly go away over time.
However, PETG in particular may stick too strongly to the PEI and rip it up. When printing PETG filament, you should either use a powder-coated sheet (which can handle the stress better) or apply something to reduce adhesion between the part and the PEI such as the glue-stick that came with your printer, a layer of painter's tape, or other materials that are known to work for the purpose.
RE: Magnetic bed sheet pitting- Prusa I3 mk3s
This is normal if adhesion was strong. Normally - for PETG - a good idea to wipe some Windex around to let a film dry as a release agent. The bubbles will resolve over time as the gasses are reabsorbed into the adhesive layer.
RE: Magnetic bed sheet pitting- Prusa I3 mk3s
Hey, thanks for the reply. I was running the bed at 75c and the object wasn't that hard to remove from the bed. I was unaware that the actual bed was a sticker which now makes a little sense now given the issue. Unfortunately I am running another print atm and cannot look any closer. I have had good success with this sheet but is there another that would do just as good or even better? Thanks again.
RE: Magnetic bed sheet pitting- Prusa I3 mk3s
Ty both for ur replys. I was concerned that I might have an issue with the printer but given ur responses this is a normal experience. Thanks for the tips! 😀
RE: Magnetic bed sheet pitting- Prusa I3 mk3s
I love the powder coated sheet. Others hate it. Definitely less adhesion than the smooth sheet, but seems to be indestructible.
The sheet I choose to use now pretty much depends on what surface finish I want. And I think the textured surface is great.
RE: Magnetic bed sheet pitting- Prusa I3 mk3s
@efryman
I mostly print PETG (85C) and have the "bobbles" all the time on the smooth PEI build plate. They normally appears around the edges of the part and sparse on the rest of the build plate. They disappear again.
Printing at higher temperature with PC (115C) more bobbles appear, but they will also disappear again.
Have a look at my models on Printables.com 😉