[Fermé] PETG not sticking to PEI sheet...  

Re: PETG not sticking to PEI sheet...

Have you tried a really strong IPA(90% or higher) to try to get some of the PLA that must be on the bed off the plastic. PLA does not react to Acetone.

Re: PETG not sticking to PEI sheet...

Have you tried a really strong IPA(90% or higher) to try to get some of the PLA that must be on the bed off the plastic. PLA does not react to Acetone.

I can get my hands on some and give that a shot, but from what I am reading online it seems PLA doesn't react to alcohol?

Re: PETG not sticking to PEI sheet...

PEI does not like fats and oils which is why it needs to be cleaned with 90+ proof isopropyl alcohol.

Re: PETG not sticking to PEI sheet...

It's surprising to hear about your issues of getting PETG to stick to the print surface.
I have printed almost 1kg of filament and it's been working flawlessly.
Due to the online information that PETG is prone to stick to the bed so much that it can be hard to remove I have not used IPA to clean the bed, I just wiped off the dust with my bare hands, intentionally getting some oil onto the bed.

I even printed a U-profile, standing on the U-end, where I was pretty concerned about it coming off, and it stuck.
It's the part in the center-right of the photo.

What seemed to be very important is the temperature, at the 85 to 90°C bed temperature during printing, the PETG sticks very well, when the print is finished letting it cool off makes the prints pop off pretty easily.

Check the first layer height and temeprature, if those are right PETG should stick just perfectly!
It's a nice material to print with (I used Hobbyking PETG, but have 2 more rolls of Prusa PETG ready)

BTW, the print quality on these prints was OK, but I printed more of those parts after the latest Slic3r update and the new prints came out much cleaner, with less stringing and smoother surfaces.

Good luck!

Re: PETG not sticking to PEI sheet...

Hi Prusa guys,

.....
[*]I have my Z-offset perfect with PLA. I have tried that offset with PETG and I have tried taking Z very far upwards so it lays down rather than smashing it into the bed, both without luck. The higher Z-offset actually made the problem worse, to the point it's just dragging around a line of filament at times (especially turning corners).
....
Thanks!

what you might be missing is that your Z needs to be a lot lower. The Z should never be dropping the filament down so that gravity brings it to the sheet. It's only too low when it starts to squish and drag out the sides. I suggest opening the printer guide going through the Z calibration again doing the first layer adjust with the "Live Z". My Z offset after calibration was -0.67 but there can be a wide range due to the rough nature of installing the Pinda sensor.

I have not printed PETG yet but the instructions state a couple of different ways to keep the PETG from sticking too much. You may wish to print one model with PLA first after getting the Z adjusted properly (low) and then use either the glue stick or Window cleaner as a transfer adhesive for the PETG because you really don't want to end up with a damaged PEI sheet.

Re: PETG not sticking to PEI sheet...

Hi Prusa guys,

.....
[*]I have my Z-offset perfect with PLA. I have tried that offset with PETG and I have tried taking Z very far upwards so it lays down rather than smashing it into the bed, both without luck. The higher Z-offset actually made the problem worse, to the point it's just dragging around a line of filament at times (especially turning corners).
....
Thanks!

what you might be missing is that your Z needs to be a lot lower. The Z should never be dropping the filament down so that gravity brings it to the sheet. It's only too low when it starts to squish and drag out the sides. I suggest opening the printer guide going through the Z calibration again doing the first layer adjust with the "Live Z". My Z offset after calibration was -0.67 but there can be a wide range due to the rough nature of installing the Pinda sensor.

I have not printed PETG yet but the instructions state a couple of different ways to keep the PETG from sticking too much. You may wish to print one model with PLA first after getting the Z adjusted properly (low) and then use either the glue stick or Window cleaner as a transfer adhesive for the PETG because you really don't want to end up with a damaged PEI sheet.

It's surprising to hear about your issues of getting PETG to stick to the print surface.
I have printed almost 1kg of filament and it's been working flawlessly.
Due to the online information that PETG is prone to stick to the bed so much that it can be hard to remove I have not used IPA to clean the bed, I just wiped off the dust with my bare hands, intentionally getting some oil onto the bed.

I even printed a U-profile, standing on the U-end, where I was pretty concerned about it coming off, and it stuck.
It's the part in the center-right of the photo.

What seemed to be very important is the temperature, at the 85 to 90°C bed temperature during printing, the PETG sticks very well, when the print is finished letting it cool off makes the prints pop off pretty easily.

Check the first layer height and temeprature, if those are right PETG should stick just perfectly!
It's a nice material to print with (I used Hobbyking PETG, but have 2 more rolls of Prusa PETG ready)

BTW, the print quality on these prints was OK, but I printed more of those parts after the latest Slic3r update and the new prints came out much cleaner, with less stringing and smoother surfaces.

Good luck!

Thanks for the info from both of you. I have PLA printing great and consistently, with my first layer looking great. Out of curiosity, are you using the same Z-offset you are using on PLA? If not, can you advise how much you are adjusting when swapping between the two? I know the installation differences of the Pinda mean you can't provide me with exact numbers to punch in, but it would be interesting to know how much you are raising Z relative to your PLA height. I.e., .1mm higher, .2mm higher, etc?

Re: PETG not sticking to PEI sheet...

Normally, you don't need to change Z between materials.
But the first layer thickness is important. Look here:

Re: PETG not sticking to PEI sheet...

If you follow the steps I have outlines below, and as already explained by others in this thread, you should have no problems printing with PETG.

PETG adhesion to the print bed can be very strong, but that's when temperatures are high. Wait for the print bed to cool dow to around 70C, and you should have no problem removing parts.

Re: PETG not sticking to PEI sheet...

I was able to print PETG without any problem until the FW/SW update and now my prints lift off. I suspect I set my Z height two high. I am going to re-calibrate once I get a chance again. What I did for quick fix was to put down painters tape with glue stick and was a quick and dirty way of getting my print to stick. I was running out the down and wanted to get this print started before I went to work and it worked great.
But like I said I was printing before without tape and I think when I uploaded the new FW/SW I went through all the cals again and probably set Z too high. PLA prints no problem but PETG does not stick. Photo of PETG from MakerGeeks printed on Painters tape and glue stick.

Re: PETG not sticking to PEI sheet...

Well, after a bit more work I finally have this figured out. Here's what I did:

That said, victory shots with a 200% blue PETG Benchy @ .2mm!

Re: PETG not sticking to PEI sheet...

Congratulation!

Just want to share my experience with the build-in First layer calibration.
IMHO, firstly it is too fast, no enough time to do fine adjustment. Secondly, it forces you to calibrate with PLA.
Theoretically, it should work for other materials but an option to choose other temperature settings do no harm and might be useful in particular cases, like yours.

Re: PETG not sticking to PEI sheet...

Congratulation!

Just want to share my experience with the build-in First layer calibration.
IMHO, firstly it is too fast, no enough time to do fine adjustment. Secondly, it forces you to calibrate with PLA.
Theoretically, it should work for other materials but an option to choose other temperature settings do no harm and might be useful in particular cases, like yours.

Yes, an option for other filament types would be awesome. Would also like to see the little square at the end get some perimeters. I might have been able to spot the .015 squish too much that I had if the perimeters were there.

Re: PETG not sticking to PEI sheet...

I was able to print PETG without any problem until the FW/SW update and now my prints lift off. I suspect I set my Z height two high. I am going to re-calibrate once I get a chance again. What I did for quick fix was to put down painters tape with glue stick and was a quick and dirty way of getting my print to stick. I was running out the down and wanted to get this print started before I went to work and it worked great.
But like I said I was printing before without tape and I think when I uploaded the new FW/SW I went through all the cals again and probably set Z too high. PLA prints no problem but PETG does not stick. Photo of PETG from MakerGeeks printed on Painters tape and glue stick.

First, as a woodturner, that vessel model is awesome.

I have a problem with lifting on corners and ends, regardless of filaments. The prints are about a few hours each, but only 50x150mm rectangle with 90° corners. Tried pei, buildtak, same issue it seems. New , clean, old, dirty, same issue. First layers look awesome, but there is what seems to be some warping in future layers as it is just those 90° corners. Some lift further than others. I use the default profiles in Slic3r as I don't know enough to change them. What I am printing requires an absolutely flat bottom.
Did you eliminate it with blue tape and glue on Petg?

Re: PETG not sticking to PEI sheet...

Hello,

I have the same problem now...

I was able to print PETG with no problem at all (even the PETG sticks to much), but now I'm facing the same problems, PETG sticking to the nozzle but not sticking to the bad.

cleaning with alcohol & windows cleaner.

I've used the same gcode file that success to print the same model that now fail...

Don't know what to do next.

Rotem

Re: PETG not sticking to PEI sheet...

Hello,

I have the same problem now...

I was able to print PETG with no problem at all (even the PETG sticks to much), but now I'm facing the same problems, PETG sticking to the nozzle but not sticking to the bad.

cleaning with alcohol & windows cleaner.

I've used the same gcode file that success to print the same model that now fail...

Don't know what to do next.

Rotem

use a brim 😉

Re: PETG not sticking to PEI sheet...

I'm starting to fight corner lift on PETG as well. At first everything stuck like crazy now it's not sticking so well on long prints, short appear to fine though. I took acetone to the sheet last weekend and that helped a little, then I switched from glue stick to Windex for PETG and that improved it a bit more but I still get corner lift to some degree on all longer prints. I've only ever printed on one side of my sheet but don't want to move to the other side until I know I can secure a replacement sheet, be it PEI, Powder Coated or some other 3rd party offering...

Re: PETG not sticking to PEI sheet...

What is this model? It looks like a leaky teapot with a tree growing out of the spout. Thanks.

Re: PETG not sticking to PEI sheet...

Have you tried cleaning with Isopropyl Alcohol? Additionally, reduce Z slightly. I had the same problem with the Z setting at -0.640 mm. I gradually decreased the setting to -0.800 mm before it would begin sticking. My best range for Z is somewhere between 0.880 and 0.890 mm. My test subject was 3D Benchy. The final dimensions for the printed Benchy were remarkably precise according to the specification. My setting was -0.880 mm.

Re: PETG not sticking to PEI sheet...

I switch a lot between PLA and PETG. PETG always sticks best on my setup when I clean the PEI sheet with acetone. For cleaning before printing PLA is use the 70% isopropyl alcohol. I print all PETG layers at 79% speed maximum. The difference in layer heigth for me is (-)0,687 PETG vs (-)0,627 PLA.