PEI bubbles on print bed?

Anyone else have bad bubbles under their bed?

I have a few spare PEI sheets I can use to replace, but what is everyone doing to avoid these?

Beat me by 2 hours.

Following as I have the same issue after printing on a hot bed.

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I don’t think there really is anything you can do. The adhesive has separated from the bed and the sheet. Replace the sheet and be cognizant of the effect it has when pulling upward on your print. Though I know it sometimes can be difficult not to. If you’re not printing with a releasing agent like magigoo you can try spraying a mixture of water and rubbing alcohol on the base of your print.

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This also tends to occur at the higher bed temperatures that are used for printing with ABS and/or Nylon. Using a thicker that stock PEI sheet may help. I remember a thread in the old forums about the adhesive used not being rated for these higher bed temperatures but I don’t remember the outcome of that thread.

I pretty much exclusively print with ABS. But this is the first time it’s bubbled up bad. With smaller bubbles I just take a vinyl squeegee and press them back down.

I know swapping the PEI is a pain and IPA is scarce so if I go through the trouble of changing it out I want to check if there’s a way to avoid it.

I had this same problem with my Taz5. I do print ABS often. My first occurrence happened during the warranty period and Aleph replaced it at no cost to me. I am positive that this is not caused by pulling objects off the bed. The center, where most things are printed, was the one area that didn’t bubble so badly. I may be wrong in this assumption, but there are three layers that make up this older style bed - Heater, Glass, and PEI. I haven’t tried to peel the PEI off, but could the bubbles be from the heater becoming separated? My second older style bed is also starting to bubble. I was going to buy another new bed when I saw that they had redesigned it. It’s now called a modular bed. It has a separate heater (with a metal top) and a separate PEI coated glass plate (1 side). You can print on either side. This will eliminate the possibility of the heater developing bubbles. If the PEI bubbles, you either make a new PEI glass plate or simply purchase a new top plate. I haven’t done the replacement to the modular bed yet, but it looks like a much better design. I waiting for the existing bed to get really bad. I bought the modular bed when it looked like Aleph wasn’t going to survive.

Best regards,
PCH

As I recall the previous threads on this topic, the going theory was that this was due to moisture in the adhesive layer. This is consistent with bubbles being more common with ABS – since the bed temperature for ABS is right around the boiling point of water, it would be more likely for bubbles to form.

There’s no good solution, as I recall – replace the adhesive and PEI is all you can do.

As a means to possibly slow down the development of the bubbles, I’ve dropped my max bed temperature to 90 C for ABS. Not sure that will help, but I’ll give it a try.

Not much that can be done to prevent the Lulzbot PEI sheet from bubbling. If you catch it early, the bubble can be squeegeed out… I’ve had good results from a plastic wax scraper for a snowboard/ski.

General guidelines I like to follow:

  • Remove prints when bed cools below 60C, Lulzbot recommends 50C.
  • Try not to pry up, ease a flat edge (ie. spatula) around the edge of print.

When it is time to replace the sheet, a thicker sheet seems to help with bubbling. But as folks have said, it will eventually happen when cycling through higher bed temps.

I noticed the bubbles starting to appear once I started printing ABS with a substantially higher bed temps. I have a spare PEI sheet but dread the work it takes to remove the old sheet.

How long have you been using that PEI sheet? Pressing the bubbles out as others have suggested is something you can do. I recently replaced a sheet of PEI on my print bed (Taz 6) and its not especially difficult to do. There is a video on you tube that tells you how to do it.

I had that problem a few years ago. I believed it was partially caused because of my impatience in removing my finished item before it was completely cooled. Soon, bubbles appeared in the PEI film as it was separating from the heated bed.
I mostly solved the problem by doing 3 things after I replaced the PEI:

  1. I let the PEI adhesive surface set a couple of days before I used it.
  2. I now always wait for complete cooling to room temp before I remove a part.
  3. On parts with a flat bottom that adhere well, I use a light weight crafting hammer to knock the part sideways with one swift blow. This avoids trying to pry the part up (difficult) and adding stress to the PEI adhesive that eventually causes separation (bubbles).

By doing the above, I have noticed an extended life of the PEI as bubbles are mostly a thing of the past. Granted, I mostly print with eSun PLA PRO while occasionally using ABS and others. I’d say about a 85/10/5 split between the three types.
Hope this helps…

Another tip for print removal is isopropyl alcohol around the edges to help release the print. Works well for ABS… allows a removal tool (ie. artist spatulas… especially the #2) to slide under and around the print.

After I purchased my Taz 6, supposedly it had only been used about 5 times, my pei started bubbling. This was my first attempt at using it. I would try to squeegee them down, but they popped back up. Decided to replace the pei and upon a closer Look, there was a tiny pin hole in the sheet. So replacing it was the only solution. Be careful on removing objects, especially ABS.

The hotter it gets and the older the sheet is the more bubbles you will get. I replace it and use a roller to apply my PEI to reduce that. Warps parts on the bed if the bubble gets big enough.

Also, more care when removing prints will reduce the chances of bubbles. The images posted above seem to me to be bad application in the first place. Get your roller and squeegee skills up!