Is this damage from PETG and how to avoid it?
I have read horror stories about PETG adhesion to the smooth PEI sheet so I have religiously applied original formula Windex to my sheet after every print. I re-use the same paper towel to apply so it builds up a nice blue color and won't remove all the surface contaminants.
I've been printing for 7 days now and all of my prints have removed without difficulty and without marking the sheet. However last night I had a fairly large print that seemed to take off some material around the edge of the model:
edit: Not sure how to embed better quality so here is an Imgur link as well: 
I had a hard time getting it in focus, but it looks like small silver flecks where the corner of the model was. I always wait for the bed to cool and even this last model popped off very easily, only requiring a slight outward bend of the sheet.
My questions are:
- Is this damage to the PEI sheet?
- If so, how does this affect the sheet? Will material bond more strongly to these silver flecks?
- How can I avoid this?
The only variable that was different with this last print is I had run a XYZ recalibration and the live Z was too close to the sheet at first. However I fixed it before the skirt was done printing, and the skirt came off without issue. The other variable is the fact this print was huge... maybe the slight bend I put in the sheet was enough to pop the corner off too strongly?
RE: Is this damage from PETG and how to avoid it?
Sorry for not including this in the original post but I'm printing with PushPlastic PETG at 245C.
RE: Is this damage from PETG and how to avoid it?
Smooth PEI sheet and petg , you should use a glue stick, petg can hold to strong and damage your bed.
After each run with a glue stick, wash your bed with dish soap, and alcohol.
Then print petg again. use fresh glue stick.
RE: Is this damage from PETG and how to avoid it?
PETG sticks well to PEI; most use Windex to form a layer of release agent. Spray on, use a paper towel to make an even layer of wet, then let it evaporate and dry to leave a coating.
When removing any plastic, even PLA, when the sheet is warm, and sometimes even when the sheet is cool, the adhesive holding the PEI to the sheet will form bubbles. These bubbles will go away with time. Heating cycles cause the adhesive to absorb them again. To hasten the absorption, flip the sheet and put the bubbles against the bed.
A quick way to cool a part and sheet for part removal is to place the sheet in the freezer for a few minutes. This is especially helpful for those PETG filaments that have a "special" bond with the PEI sheet.
And - after soap and water, do NOT use alcohol. Water is the best rinse out there. Proper course of cleaning is alcohol to remove PLA residues, acetone to refresh a smooth PEI sheet (no acetone on PC PEI sheets), then wash with soap and water to remove whatever the alcohol and acetone have lifted.
RE: Is this damage from PETG and how to avoid it?
When removing any plastic, even PLA, when the sheet is warm, and sometimes even when the sheet is cool, the adhesive holding the PEI to the sheet will form bubbles. These bubbles will go away with time. Heating cycles cause the adhesive to absorb them again. To hasten the absorption, flip the sheet and put the bubbles against the bed.
Thank you for this! It turns out the silver flecks in the image I posted above were indeed bubbles. A few prints later I tried to find them and they are mysteriously gone. Good to know!
A quick way to cool a part and sheet for part removal is to place the sheet in the freezer for a few minutes. This is especially helpful for those PETG filaments that have a "special" bond with the PEI sheet.
Also really good to know... I had considered this, as the ambient temperature in my garage is pretty high right now (around 40C) so cooling down that far takes 10-15 minutes. I get impatient especially for small prints and things like first layer calibration. I thought perhaps condensation from the refrigerator would be an issue, but I guess if it is heated/dried soon afterward it wouldn't be an issue.
And - after soap and water, do NOT use alcohol. Water is the best rinse out there. Proper course of cleaning is alcohol to remove PLA residues, acetone to refresh a smooth PEI sheet (no acetone on PC PEI sheets), then wash with soap and water to remove whatever the alcohol and acetone have lifted.
Not sure I understand what you're saying here... for PETG my cleaning routine has been just Windex, but for PLA I use 91% isopropyl alcohol. I haven't had to use acetone yet. Are you suggesting a wipe with a damp paper towel after the iso wipe?
RE: Is this damage from PETG and how to avoid it?
Soap and water actually cleans the bed of contaminants like finger oils. Alcohol simply dilutes the oil and spreads it over the entire surface. I've used finger prints as a release agent for PETG that likes to stick using alcohol as a thinner. Works really well if you have oily hands. Windex left to dry on the sheet is also a good PETG release agent.
But when printing PLA, soap and water is best. Alcohol can be used to remove PLA residue that forms, but follow the alcohol with soap and water.
Why soap and water? It is a matter of volume. A few gallons of hot water rinses contaminants away; a few grams of alcohol can't come close to that cleaning power.
RE: Is this damage from PETG and how to avoid it?
As per Prusa's Mk3 printer manual, avoid using any Isopropyl Alcohol to clean the PEI bed before you print with PETG as that can cause the PETG to adhere too well to the PEI surface.
Use either glue stick as a separation layer on the PEI after using Isopropyl Alcohol or clean the PEI with a "Windex" type glass cleaner instead.
RE: Is this damage from PETG and how to avoid it?
I lift the z height slightly with petg - otherwise i find it does come too close to glueing intself to the sheet.
Let it cool to 45c or less before even trying to remove
RE: Is this damage from PETG and how to avoid it?
I have read horror stories about PETG adhesion to the smooth PEI sheet so I have religiously applied original formula Windex to my sheet after every print. I re-use the same paper towel to apply so it builds up a nice blue color and won't remove all the surface contaminants.
I've been printing for 7 days now and all of my prints have removed without difficulty and without marking the sheet. However last night I had a fairly large print that seemed to take off some material around the edge of the model:
edit: Not sure how to embed better quality so here is an Imgur link as well:
I had a hard time getting it in focus, but it looks like small silver flecks where the corner of the model was. I always wait for the bed to cool and even this last model popped off very easily, only requiring a slight outward bend of the sheet.
My questions are:
- Is this damage to the PEI sheet?
- If so, how does this affect the sheet? Will material bond more strongly to these silver flecks?
- How can I avoid this?
The only variable that was different with this last print is I had run a XYZ recalibration and the live Z was too close to the sheet at first. However I fixed it before the skirt was done printing, and the skirt came off without issue. The other variable is the fact this print was huge... maybe the slight bend I put in the sheet was enough to pop the corner off too strongly?
I routinely switch between PLA and PETG and I use white cotton gloves to reduce hand grease from the print surfaces. I print about 12 hours per day every day and use 2 PEI sheets rotating sides and sheets. Every time I print I use another SIDE of the other sheet that is cooled down, taking the hot sheet off the printer to cool. This works perfectly with no real thought. I have NEVER had to use soap and water. Just Windex between prints. I have over 40 days on those sheets and counting. No permanent bubbles, scratches, marks, or sticking.
Now to get the PC sheets to work as good. I love those things but they became a pain quickly.
Just my 2 cents.
RAH
I am the inveterate tinkerer. I can tink up most anything.
RE: Is this damage from PETG and how to avoid it?
I have a powder coated sheet on the way -- can you share your experience with them? The Prusa documentation seems to indicate simply cleaning it with iso is enough for PETG.
RE: Is this damage from PETG and how to avoid it?
I have a powder coated sheet on the way -- can you share your experience with them? The Prusa documentation seems to indicate simply cleaning it with iso is enough for PETG.
RE: Is this damage from PETG and how to avoid it?
I have a powder coated sheet on the way -- can you share your experience with them? The Prusa documentation seems to indicate simply cleaning it with iso is enough for PETG.
Sinoth,
I just added some comments on my experience to the discussion mentioned by Tim.
RAH
I am the inveterate tinkerer. I can tink up most anything.