PEI: Giving It a Try


#1

I’ve heard great things about the PEI print surface and decided to give it a try. Materials used are 0.03" thick 12" by 12" sheet of PEI, 12" by 12" 3M 468MP adhesive and a 12" x 8-7/16" sheet of glass. For me total cost of materials was $21.35 USD.

Setup was a little sketchy. That PEI and adhesive are tough stuff, glass was the weakest layer. If you’ve never bonded to layers with adhesive or used transfer tape then watch some youtube videos, get some ideas about how it’s done. I wont give any advice because I don’t think I did it best. I did somehow succeed in getting the glass and PEI bonded without breaking the glass. Oddly the 12" PEI and adhesive were shy of the 12" glass.

The adhesive and 0.03" PEI add about 1mm to the build platform. I regret that I can’t report the added weight on the Y axis; I don’t have a precision scale.

Heated print bed sandwich!

I was surprised by the temperature difference between the top and bottom of the heat bed. 90° on bottom and 60° on top. I let it heat for quite a while and if never broke 60° at 90° bed temp. Consider this is at the edge of the build platform.

First print, no failure. For my first print I printed the last PETG print I did on bare glass. I did have some support material come loose, but it wasn’t a show stopper. Next I’ll try to print a model I couldn’t get to succeed on bare glass due to curling.


#2

I glued my PEI sheet to a 5mm (overkill) aluminium plate and I can print at 70c with no issue.
You might want to lower your Z-offset a bit so it squished a bit more on the bed for the first layer.

That being said, even with low to no squish, I have yet to have a print fail with PETG. It stick to PEI super nicely at 70c for me.

I’d be a bit concerned if the top of your PEI sheet is 30c less than the heatbed PCB, you could try adding a layer of insulation to the bottom of your bed (cork/heavy cardboard) so the heat doesn’t dissipate through the bottom of the printer.


#3

Thanks for the advice. I have some sheets of cork, I’ll try insulating the bottom of the PCB heater.


#4

Well that PETG print that failed 3 times on bare glass due to curling succeeding on PEI. That first layer stayed down perfectly. Too well in fact, I can’t get the print off. I’ve got it in the freezer now, if cold doesn’t free it I’ll try a bit of heat.


#5

Yeah that’s something I forgot to mention. I had some issue with ABS that I couldn’t remove from a cold PEI sheet (I had to scrap the sheet). I think PETG stick even harder, this is something to consider.

I have some gcode that set the bed to 40-45c at the end of a print. I find its easier to remove the part at such temperature than room temperature or colder.


#6

You are the man, @AndreQ! Freezer didn’t do a bit of good. Heated it up th 50° and it popped right off.


#7

What glue did you use? I’m hoping to get my PEI this week, tossing up between the 3m and glue.


#8

My bad, I should have written “stuck”. I used the high heat 3M tape everyone seem to use on reprap forum or reddit. I forgot the link, but it was from Digikey.


#9

I just applied mine, and couldn’t get it remotely flat :frowning: the sheets of tape I got had creases from being rolled up… Even the sections that applied well don’t feel flat. Not sure where to go from here, removing it will be the first step.


#10

Bummer! I wonder if some heat and a squeegee/spatula would help some of those creases in the adhesive level out.

Lulzbot has a guide that might help with the removal and reapplication. https://ohai.lulzbot.com/project/mini-replacing-pei/maintenance-repairs/

My 3M adhesive came in flat sheets between two pieces of cardboard. I understand why now. I’m curious how thick the PEI you’re using is. The 0.03" thick PEI I used was quite rigid and would not deform easily.


#11

I am only using the .3mm PEI, so .011" I think? a very thin sheet - why, well beggers can’t be choosers.

I contacted the seller to see what we could organise - I was willing to pay for it as I shouldn’t have tried to use it seeing as it was damaged. He came to the party and is sending me replacement 468 express, he is posting it in sheets this time instead of a roll.

I have been doing some reading and apparently you can wet apply it with windex, so I will probably give that a go, I have done that before with other large adhesives with excellent results.


#12

We’ll that’s some good news. From the images in that lulzbot guide it appears they’re using thin PEI as well. For a printing surface I don’t imagine it matters just affects how you might apply it. There is certainly no cutting a 0.03" or 0.76mm sheet with a razor blade like lulzbot describes, you have to score and snap. That operation was very sketchy and I’m shocked I didn’t break the glass I just stuck it to.