Hello Everyone,
I noticed something odd today, it looks like part of the PEI surface on my heated bed seems to be bubbling and lifting off.
I’ve attached photos of what my bed looks like. Any thoughts? Is this fixable, or do I need to order another PEI sheet?
Actually, speaking of which, are there instructions on how to replace the PEI sheet?
Thanks,
Dower
You look to have damage to the surface in one spot, which will let oils, dust, and air come into contact with the adhesive causing early failure of it…
There is a guide on PEI replacement.
https://ohai.lulzbot.com/project/mini-replacing-pei/maintenance-repairs/
I do not know if it is any good since I have a Taz myself. 
Bubbles under the PEI surface will happen with time. If your Lulzbot is within the warranty window, contact support and they will send you a new heater, glass plate, and PEI surface assembly ready to install no questions asked. I should know, they replaced mine 3 times. 
Great support!
If you are outside of warranty, Lulzbot sells PEI sheet replacements. The replacement instructions are in the last post.
You can prolong your PEI sheet and reduce bubbles by making sure you remove parts, like ABS, at their recommended removal temp, in this case 50C, and being careful not to let the bed cool completely before removing it or heating the bed back up to remove it. Best practice is to remove it right when the bed hits its recommended removal temp.
Adding a bed temp hold also helps if you can’t be right by the printer when it finishes.
I have to keep an eye on my prints to pull them off at the right time so holding the bed temperature would be great so I don’t have to stand around waiting. Do you have some G-code to add to the end of the print to make that happen? I think I remember seeing a section in Cura to add or modify end of print commands.
I have a month old Taz which is doing the same thing, although it has smaller bubbles and not those 2 huge ones. All the tiny bubbles were present before using it. On the front edge of the PEI film, it’s very rough and coming up. It snags things when I try to clean the surface. I sent pics in to support. They said it’s normal, and I could sand the edge if I wanted.
A bunch of small bubbles ~1mm should be okay. But I’d let LB support know if it gets worse… 2cm+. As for the edges, that should be okay also…
Support really is pretty good on these machines. The PEI sheet will ultimately bubble, but if it does within the 1yr warranty, they are good about replacing. After the year (or possibly the third replacement), you’re on your own.
They are larger than 1mm, and change when heated. I can push them around under the surface easily with my fingernail. My concern was since they are kind of big right now, that they would coalesce and form larger ones like the OP has. That and if there are bubbles, that means it’s not quite level in that spot and I didn’t want it to potentially affect prints.
Replace your end gcode with this (it is located under expert mode under the start/end gcode tab):
M400
M104 S0 ; Hotend off
M140 S0 ; heated bed heater off (if you have it)
M107 ; fans off
G92 E0 ; set extruder to 0
G1 E-3 F300 ; retract a bit to relieve pressure
G1 X5 Y5 Z156 F10000 ; move to cooling positioning
M190 R50 ; wait for bed to cool to ABS removal Temp***
G1 X145 Y175 Z156 F1000 ; move to cooling positioning
M140 S50 ; turn bed temp to ABS removal temp***
M84 ; steppers off
G4 S3600 ; Hold bed temp for one hour S***
M140 S0 ;Shut off heated bed
G90 ; absolute positioning
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You will need to modify the code on the lines with ***'s. This one is set up for ABS, but all you have to do is change the 50’s to whatever the recommended removal temp is for your material. Also, change the S3600 for whatever hold time you want. Right now it’s set for 1 hour. You could set it for 8 hours if you wanted if it was going to finish the print in the middle of the night.
Adding a bed temp hold also helps if you can’t be right by the printer when it finishes.[/quote]
I have a month old Taz which is doing the same thing, although it has smaller bubbles and not those 2 huge ones. All the tiny bubbles were present before using it. On the front edge of the PEI film, it’s very rough and coming up. It snags things when I try to clean the surface. I sent pics in to support. They said it’s normal, and I could sand the edge if I wanted.[/quote]
Tiny bubbles are normal. When they conglomerate into giant bubbles and affect prints, it’s not normal and they’ll replace it. After the year warranty, though, you’ll have to replace it yourself. It’s not particularly hard, just a big time consuming.
Those are due to the application of the adhesive. The adhesive has curled on itself slightly and therefore thicker. Unfortunately, its pretty common and no real way of rolling out or removing the air bubbles. Keep an eye on it. LB will replace if it gets worse.
I’ve never seen the PEI so badly before… but I guess it could happen.
Did you send that same picture to LB support? I think it should be compelling enough for a replacement.
Yes, that was one of them I sent in.
It seems that Lulzbot is no longer replacing these under warranty.
I received a reply with instructions on how to replace the PEI sheet, and basically that this is a normal wear item.
No offer in sight to replace the sheet, even though my bubbles were from a little over a month of use.
Since then, I bought a whole new heated bed, along with two PEI sheets.
That is probably what they hoped I would do.
Sorry.
Where do you find recommended removal temp?
For some reason the mini page doesnt list the removal temp. here is the removal temps for the taz which should be the same LulzBot | Taz 6 cura profiles
Thanks!
