PETG 1st cm Peels up  

RE: PETG 1st cm Peels up

Wellp, I can't figure out how to edit my post... So I will repost a larger image... 

RE: PETG 1st cm Peels up

Your bed is contaminated. IPA and acetone do not remove finger oils very well in how they are typically used. Take the bed to the sink and wash with hot water and dish soap (no additives for skin, scent, etc) and scrub/rinse well/dry using clean paper towels.

do not touch the build sheet with your hands - handle it only by the edges now, or wear disposable gloves.

Now wipe down with some windex and you should be all set.

RE: PETG 1st cm Peels up

Thanks @vintagepc.  I had suspected that, and I tried that, and I just tried it again.  Still No luck.    

hmmmmm?

RE: PETG 1st cm Peels up

PS - that photo shows the bed is really really dirty. Way too much whatever it is you're using to prevent sticking.

Soap and hot water - and try following this process.  And don't use things like Windex if you're having adhesion issues with PET.  I had to go ultra clean with Amazon PETG. It was almost as bad as trying to keep PLA sticking to the PEI. And, most important, soap and water are the LAST step to use if you want ultra clean.

Hot Water wash: often, as needed
Handle the bed only by the edges.
Wash the bed in hot water, use a fresh paper towel as a wash cloth, with a few drops of plain dish soap (Dawn, unscented, no anti-bacterial, etc.). Rinse well in hot water - if you have very soft water, rinse a bit longer.
Dry the bed with a fresh paper towel.
Handle the bed only by the edges.
Place bed on printer.

Alcohol rinse: every few prints
Once in a while, an alcohol rinse is helpful to remove PLA residue. It does not remove finger oils.
Pour a 5 cm puddle of 91%+ alcohol in the middle of the bed, with clean hands use a fresh paper towel to scrub the bed. Wipe up all the alcohol.

Streak test: when contamination is suspected
With a fresh piece of paper towel, and very clean fingers, dampen the towel with 91%+ alcohol, and wipe the bed side to side moving back to front, like you're painting it with alcohol. The alcohol should be thin enough on the towel it quickly evaporates. If you see any streaks, the bed is dirty and needs a wash.

Acetone wash: infrequent
Pour a 2 cm puddle of acetone on the bed, scrub it around with a fresh paper towel. It will evaporate fast as you clean. This step removes PEI oxides that form over time and with heat, and improves PLA adhesion to a like new state.

RE: PETG 1st cm Peels up

I think it depends hightly on how seasoned your bed is - I have to use windex with Amazon PETG or I'm pretty sure I'd never get it off. Had a few close calls when I swapped filaments and it didn't quite all get purged... got a blob of black in my purge line that did NOT want to come off...

But back to the OP - the dishwashing liquid method is A+ for me when I have this exact issue with PETG. 

You should probably also double-check your Live Z still forms a good layer; if not it's gonna give you a bear of a time getting proper adhesion, and next to a dirty bed, it's usually the second biggest cause of failed bed adhesion.

RE: PETG 1st cm Peels up

Thanks @tim-m30 and @vintagepc, Greatly appreciate your help.

I was trying glue stick in that picture.  My mk2s still prints PETG like a boss.  But with that machine - no glue stick, no come off - lol...

I am Leary of trying PETG on the MK3 completely clean - I have heard horror stories of people messing up the sheet trying to get it off.  I had a little luck today slowing down the first layer, and increasing the filament temp 2 degrees...  I have been playing with the Z height now...  I might try the completely clean attempt here in a minute.  

Again, thanks

RE: PETG 1st cm Peels up

As an aside, whether it fuses or not seems dependent on the temperature - higher temperature PETGs are more likely to stick and not let go; lower temperature ones (Amazon and Hatchbox, for example) tend to be less of a problem. Good luck - you're just experiencing something most of us have at some point or another. As is said, "Experience is what happens when you don't get what you expect!"

RE: PETG 1st cm Peels up

Posted by: vintagepc

[...] whether it fuses or not seems dependent on the temperature - higher temperature PETGs are more likely to stick and not let go; lower temperature ones (Amazon and Hatchbox, for example) tend to be less of a problem.

*sigh* Yes, be wary when trying new filaments that print at higher temps than you're used to. I had printed PETG for months with few issues when I tried 3DXTech's matte PETG. Great stuff, but it prints at 260C and really grabbed onto my PEI. I managed to tear off a couple of chunks of my PEI surface during removal. I've since learned to apply some glue stick or something like MagiGoo when trying higher temp prints. Here's the poor ripped up and poorly patched PEI,  and here's the same part in the same filament popping off effortlessly after a print using MagiGoo.

I've since replaced that PEI sheet. Having a spare sheet on hand is a good idea. I tried nylon for the 1st time this week, and was pleased to find it worked well with a thick layer of glue stick, even though it had no interest in sticking to bare PEI. Every material is different. Definitely consider reserving one surface for PETG or other "unknown" materials. 

RE: PETG 1st cm Peels up

No argument from me - FIRST TEST ADHESION WITH A SMALL PART - is great advice for any new filament.  I have to admit even Amazon PETG at 250c grabs the PEI at the purge line fairly well, especially where I've scratched the PEI with tweezers in a few places; wellenough I usually leave a nasty fingerprint down the purge length when I print PETG.  An early spool of clear Prusa PETG adhered like it was super glued down - that was with a sorta clean bed; for it Windex or gluestick is a must. 

I need to add a Not an Expert / Your Mileage May Vary disclaimer to my sig.