What caused this to happen to the PEI sheet? And other PEI questions.

My printer did not put any filament down today in the top left, and instead it seems like the PEI sheet has burned and bubbled up. What would cause this, and how can I prevent it in the future?

There were pockets of air that were starting to occur, and I already had ordered a replacement PEI sheet to install. I am wondering what I can do to avoid his in the future. Was it just a cause of the PEI sheet starting to pull away from the print bed?

Also, how long should a PEI sheet last? I have been using this printer since January of 2017, and have run approximately 700 print jobs, the average length of which is around 30 minutes. Does this seem like a lot of use for the life of one PEI sheet? Is there anything I should be doing to extend its life?

Mine looked about the same after a year… I started having adhesion problems… I think it was $45 and a new PEI sheet and problem solved. Worth every penny!

This was also posted on reddit and determined that the auto level procedure was not done correctly so the nozzle went in to pei sheet while printing. Always watch the autolevel and first layer for these issues.

It looks like a combination of a few things:

  • Autolevel not working and the nozzle is too close to the bed initially - nozzle or discs may have leftover filament or the wiper pad is dirty. Check those regularly and clean the left-over filament… flip the pad or reverse for best cleaning.

  • Part removal - Try not to pry up or “knock” the object off the bed. Get a good removal tool. Something thin that can slide under the print. Buildtak makes a good tool, but a smaller paint knife (the number 2 in this set) helps to initially get under the print. I use the smaller spatula to get under the print and start working around the print, then slide the larger under to help the smaller tool continue around the perimeter of the print.

Additional “best practices” with the PEI:

  • Make sure the bed cools below 60C (50C is the LB recommended temp) before removing parts - The 3M adhesive that is used is still soft at higher temps, therefore the stress of removing objects can cause the PEI to lift from the glass.

  • Avoid letting the object cool completely - Especially with ABS, it will contract and stress the PEI film / adhesive. If it does cool completely, try heating the bed to 100C for 5min then let it cool to 50C for removal.

    This sounds like a pain, but the PEI really helps to simplify the adhesion of objects to the bed. You don’t need messy products like hair spray or ABS juice. Tape and glue sticks help with some filament types. Just get to know the PEI and it will save headaches in general.

Hope these tips help.