Print sheet destroyed after removing headbands  

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Juan Orlandini
(@juan-orlandini)
New Member

Hello all,

Just got my Prusa last Monday and I've done a few prints with PLA and they came out perfect. Switched over to PETG and did a small test and it also worked perfectly.

Last night I started off the stacked 8 head band print and it all seemed to go well, but when I went to remove the parts, they were super stuck to the print sheet. So much so that when I flexed the PEI coating peeled off. Even after I removed the parts, there were little bits left and they were damn near impossible to scrape off. See the picture. Before printing, I did clean with denatured alcohol (91%). Hot end was set at 230 and bed at 80. 

What did I do wrong?

Thanks,

Juan 

Posted : 03/05/2020 8:50 pm
Lars Deutsch
(@lars-deutsch)
New Member

You printed too close to the printed. 

Posted : 03/05/2020 9:14 pm
Juan Orlandini
(@juan-orlandini)
New Member

agh! I was afraid of that. Trying to do the Z adjustment has been hard.

Posted : 03/05/2020 10:27 pm
phil.s6
(@phil-s6)
Trusted Member

@tachijuan

Also, don't use alcohol for PETG.  Use Windex.  It help reduce the adhesion a bit.

Posted : 03/05/2020 10:35 pm
RH_Dreambox
(@rh_dreambox)
Prominent Member

@tachijuan It was sad that you ruined your bed, but do as phil-s6 says, use Windex or some other window cleaner.
Spray Windex on the bed, spread it over the surface and then let it dry. You should not wipe the window cleaner with any paper, because then PETG will stick too hard.
If the printout is stuck very hard, you can put it in the freezer for 10 minutes. Then it loosens more easily.

Bear MK3 with Bondtech extruder...
Posted : 04/05/2020 3:58 pm
Juan Orlandini
(@juan-orlandini)
New Member

Thank you all

Posted : 04/05/2020 4:01 pm
Milos V.
(@milos-v)
Honorable Member

I can recommand using the powder coated sheets for PETG, after it cools down, it usually jumps out itself. Sure, if you do not need the smooth first layer. Otherwise as advised, for PETG the PEI sheet should not be so clean as for PLA. It is better to use one side for PLA, and other side for PETG. Because otherwise if you are using Windex for PETG, you have to remove it later on for PLA to stick good again.

Posted : 04/05/2020 4:29 pm
bobstro
(@bobstro)
Illustrious Member

After an initial mishap with high-temp PETG, I managed to avoid damaging my PEI sheets for nearly 2 years. During the big COVID printing push, I've trashed 2 of them. The best solution I've found is slathering a thick layer of glue stick on the sheet for PETG. It's not what I'd recommend for normal printing, but I need stuff to stick and remove without issue. It also requires a washing step before passing the frames on for assembly.

My notes and disclaimers on 3D printing and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan...
Posted : 04/05/2020 4:43 pm
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