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Bed temp for PETG, Does the MK3 need higher than recommended?  

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kirby
(@kirby)
Trusted Member
Bed temp for PETG, Does the MK3 need higher than recommended?

I have two different spools of PETG (MakerGeeks and MatterHackers) the sticker on the spool recommends 60C bed temp, so I while ago I created a filament profile in PrusaSlic3r for one of them, basing it on Prusament PETG, but changing the bed temp to 60/60C (60C on first layer, 60C on the rest). Some time passed...

Yesterday I was trying to print what was is basically a flat bar (about 7in x 2in and maybe 0.5in tall). Twice, the left side pulled up enough to ruin the print because when the print head was moving over that edge, it was springing up and down a little, so the top layers were getting laid down on a moving base. 

Doing some research, PETG edges pulling up is often a sign of too low of a bed temp. So, I looked at two PET(G) profiles built into PrusaSlic3r and saw they were both 85C/90C. I tried 80C/85C (80 on first layer, 85 on the rest) and the part came out ok. It's a little warped, but I may have done that by taking it of the build plate too soon.

Looking around shopping sites, I see many spools of PETG from various companies that recommend a 60C, but clearly Prusament PETG recommends 85/90C and I got better results with two different PETG spools at at least 80C. Why the difference? I'm on an MK3. Is it the magnetic spring steel build plate?

Posted : 23/12/2019 6:07 pm
kmac1036
(@kmac1036)
Active Member
RE: Bed temp for PETG, Does the MK3 need higher than recommended?

I don't think the bed should be springing up at all it should stay flat. when is the last time you cleaned your sheet? it could be it lost it's tact just by usage. check the maintenance notes on cleaning the steel sheet if you haven't done so. I ran mine at 60c last night (first print on my kit 3s) with the PLA that shipped with the box and it printed fine, the batman logo from the SD card.

Printrbot Play & new i3 MK3s owner....
Posted : 23/12/2019 7:10 pm
kirby
(@kirby)
Trusted Member
Topic starter answered:
RE: Bed temp for PETG, Does the MK3 need higher than recommended?

@kmac1036

The bed itself isn't springing up, it's the part I'm printing. The left edge is shrinking and lifting off the print bed, which causes sort of a spring effect as the print head comes back over it to lay down newer layers. I know it is shrinking, I can see the thickness is less on the left side than the right. I also cleaned the sheet before printing. Also, I'm asking specifically about PETG temps.

Posted : 24/12/2019 4:06 am
pbnj
 pbnj
(@pbnj)
Trusted Member
RE: Bed temp for PETG, Does the MK3 need higher than recommended?

I have found that 60 will work ok for the smooth bed, but can be hard to remove. I normally print at 85 for all layers using the textured bed. When it is cool the part falls off with out a problem. Always clean the bed with Isopropyl alcohol before starting. Currently into a project that will take about 6o hours to complete 10 parts. Currently on second of 4 prints sessions for the project, no problems.

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Posted : 24/12/2019 5:18 am
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