Replace PEI without removing heatbed  

Re: Replace PEI without removing heatbed

Yes. There are many threads with examples of people who have replaced it without removing the bed from the machine.

I soaked paper towels in Mineral Spirits and let them sit on top of the bed for 45mins or so. Then started to peal it up, putting mineral spirits under to soften the glue. Took a while to get all the glue residue off the bed, but quite doable.

Other's have used that 3M solution, others Limona<something> and others turpentine. The freezing step can certainly help, but is not necessary.

If you search the forum you will find one person who did damage the bed, when some of the heating traces were damaged as they took of the PEI sheet.

Re: Replace PEI without removing heatbed

➡ just this friday I replaced the pei at my genuine i3 mk2 and tried to remove the old surface without removing the heatbed.
but I found it very hard to "peel" it off from the pcb, even with the aid of d-limonen and/or a heat gun. this 3M glue really is tough stuff !

💡 because I wouldn't hurt the surface of the pcb, I decided to disassemble it and put it into the freezer as recommended in the replacement video.
after that the pei came off from the pcb much easier, and in big chunks (not the small, nibbled ones as before) without the risk of damaging the unprotected pcb surface.

afterwards I put the paper towels on top of the pcb and soaked them with d-limonen. to scrap the glue off from the pcb I first tried an old smartcard.... but it was a little bit to weak, so I used the straight edge of an old compact cassette cover instead, which worked pretty well. in fact I needed 3 "rounds" of soaking d-limonen and scraping off the glue... incredible how much glue there was.

now the heatbed looks as good as brand-new, even the area with the little hole in the middle (where I once ripped the sheet) and where I've tinkered it with a small kapton patch, looks pristine.

Re: Replace PEI without removing heatbed

I have replaced PEI x2 in a month and I highly recommend just removing it. Its not that hard.

My steps...
1. Place in freezer (cable attached is fine) for 20 mins.
2. Remove PEI by lifting corner. It should be nice and firm and pop off nicely after you get an edge started.
3. Place papertowls on bed which still has all the glue.
4. Power Turpentine Gum Spirits (a type of paint thinner) onto the paper towels so they are soaked.
a. Recommend having a plastic bag of sorts that will fit the bed and paper towels in while it soaks since the turpentine has very strong odor.
5. Allow to soak for ~40 mins.
6. Use large scraper, like a dry wall spackler, to remove as much glue as possible and quickly. Bigger tools with a slightly more blunt edge work well.
7. Usually a little glue is leftover since it starts to dry quickly. Soak again for another 20 mins and repeat to get the last of it.
8. Use alcohol and a separate cloth to remove any residue/turpentine. Remember to use new areas of cloth to not re-apply any turpentine.
9. Place new PEI. Avoid touching the board directly and applying natural body oils. If you do, wipe with alcohol again before letting the PEI seal to that area.

Re: Replace PEI without removing heatbed

Replaced mine a few weeks ago without removing the heatbed. It's not really bad, it works best to "roll" it off the bed using a pipe or round pole of wood. Do not to try to rip it off in a 90° angle staight upwards, it's hard to get it off that way.

Advantage of the "roll off" way: For me most of the glue stayed in the PEI sheet and only a little amout kept stuck on the bed -> easier to clean.

Re: Replace PEI without removing heatbed

I designed that scraper for that use: https://www.thingiverse.com/thing:2657335
I have no clue for another use.

Re: Replace PEI without removing heatbed

I just replaced my PEI sheet about a week ago and while I'm sure it's possible to remove and replace without removing the bed, I think it's worth the extra 10-15 minutes it takes in the overall process to remove it. However, I would suggest that you re-mount the heatbed before applying the new sheet since it makes it so much easier to install it on the stable platform. At the risk of repeating some already great instructions, here was my process that worked better than expected.

1. Remove Heatbed
2. Place in freezer for 30 minutes (I left the cables and the plastic cover on the bed in place)
3. Remove sheet. In my case it came off in about 3 large pieces as it separated along the damaged spots.
4. Cover with paper towels and soak in D-Limonene (Amazon: https://www.amazon.com/gp/product/B073RQ3CBC/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1 )
5. After applying the Limonene, I placed the whole bed with the paper towels inside a 1-quart ZipLoc back with the cables hanging out. I let it sit for 1 hour. NOTE: Make sure to keep the bed print-side up and limit the contact of the solvent with the bottom of the bed as it can also dissolve the adhesive on the tape that holds the thermistor in place.
6. I then used a putty knife to scrape off the glue. It was metal which probably isn't the best idea but I was really careful and I was able to get 95% of the glue off on the first try. I then just used the soaked paper towels to re-wet the areas where there was a little glue left and used the scraper to completely clear the bed.
7. After all the glue was gone, I rinsed off the bed with warm tap water. Be sure to rinse the bottom of the bed too.
8. Re-mount the bed to the printer and re-attach the cables to the RAMBO.
9. Clean the bed with 91% IPA.
10. Apply the new PEI sheet as described in the Prusa guide. I just pressed hard with my fingers to affix it to the bed as I worked about 1 inch at a time from the left side to the right.
11. Re-run the full XYZ calibration and Live-Z adjustment. In my case the Live Z was almost identical to the values prior to the replacement.

Re: Replace PEI without removing heatbed

I live in Minnesota, it will be colder than most freezers outside in a few weeks, I plan to set my printer outside for a short time to allow it to chill out, then strip off the old and bring it inside for the normal glue removal/reinstall process.

I also wondered if setting the entire unit in a freezer would avoid a disassembly step?