Help: Stuck TOO well to PEI+MIC6!

[NF6X]

I have one of the fantastic MIC6 with pre-applied PEI from a previous production run by Insta. It sat idle for a long time, and I finally got around to installing it a few weeks ago. I had been generally printing PLA with the extruder at 200ºC and the bed at 60ºC. I had trouble with corners peeling up on large prints, and I ended up dialing in 70ºC bed temperature with a 5-perimeter skirt. That has been working very nicely.

I just ordered some conductive PLA from Proto-pasta, for use printing fixtures for ESD (static electricity) sensitive things. They recommend higher temperatures than one would use for regular PLA in the 220ºC-230ºC range, and note that layer adhesion and strength are not as good as regular PLA. For my first test print, I tried printing a fairly long fixture for holding SMT tapes during PCB assembly. I set the extruder at 225ºC and left the bed at 70ºC.

Boy, was that a mistake! The layer adhesion was just good enough to hold together during printing, but too weak to apply much force to the part without pieces breaking off. Well, body to body supports pop out nicely, at least. But the bottom layer is stuck solidly to the PEI surface. I can't scrape it off with a fingernail, and of course the bottom layer is thin enough that it's difficult to even feel the edges with a fingernail. I'm concerned that there's no way to remove this failed print without damaging my PEI surface!

I tried freezing the plate to see if that would help release the build, but that shot in the dark didn't help.

Before I try anything else, I'd like to see if any of you more experienced folks have any suggestions. I hope that I can preserve my PEI surface, because I doubt that I can do nearly as good a job applying a new one as Insta did. When I applied PEI to my original glass build plate, I had a LOT more bubbles than my beautiful PEI + MIC6 plate arrived with.

Is there any hope, or did I done goof up bad?

[Jules]

Not a clue! That looks like it's stuck on there so tight that prying it off is just not going to be an option.

Looks like they were completely correct about layer bonding being horrible too.

I'd try VERY carefully prying it off with a razor blade in a holder (and use gloves so you don't cut yourself), get down at eye level and try to get the edge under a corner. Slowly pry up one corner and you might be able to work a thin spatula underneath. Your first layer might have been too thin too...looks very flat.

If you can't get it off, the PEI sheet is about 25$ to replace, so if you damage it you can buy the sheet tape and a sheet of PEI and apply it yourself. But PEI will take a lot of prying that would damage tape...you might be able to get it scraped off if you are careful. As much as you can and then maybe sand the remnants with a fine grade sandpaper.

[zemlin]

I haven't had that happen with PLA, but I've had a few ABS prints bond too well when I overs-squish the first layer.
I have one sheet with a couple of small divots where I was scraping the part off with a razor blade, and the blade flexed enough to dig the PEI - so be careful if you try to scrape it with a flexible blade. After that I softened the part material with acetone before scraping it off the sheet.

Acetone won't work with PLA (I assume), but I'm wondering about PLA's lousy heat resistance. Maybe heating up the bed and then some gentle scraping to remove the stuck material. No experience here - just guessing.

[NF6X]

Thanks for the suggestions! Maybe I'll try warming the bed to a higher than normal temp to see if that helps before I go to work with a razor blade. Maybe I should look into getting another PEI+MIC6 plate to keep on hand as a backup.

[atomic_peach]

Does methylene chloride react with PEI? You could try using that to dissolve the PLA off. It's quite aggressive and used in some aluminum paint strippers; but given how nasty this stuff is, leave it as a last resort unless you've worked with it before.

[insta]

The PEI is super resilient. Get a wide carpet-scraper (4" wide razor blade, basically), hold it at a very very low angle, and gently scrape the stuck plastic off.

I used to be very ginger with my PEI, but now I just dig chisels and stuff into it to pop parts off (granted, I can also replace it easier...). There's a reason I use the much thicker stuff on these builds

[NF6X]

I think I've found a technique that works. Heating the build plate to 110ºC makes the filament fairly soft. I have sliced off most of the mass with a sharp razor. It appears that I can burnish off the remainder with an electric drafting eraser. Periodic re-heating of the plate is necessary, and care is necessary while handling the hot plate and sharp blades. I use the same cut-resistant gloves that one of the other regulars here (zemlin, IIRC) recommended while I'm doing this sort of thing. This chews through the eraser very quickly, though. I will need to buy a bunch of eraser refills before I resume the task. I think this has a good chance of ultimate success.

I would still like to buy a spare plate, though, so that my next disaster doesn't take my printer out of commission while I'm cleaning up the mess.

[Jules]

Glad you found something that's working........that was one stuck print!

[NF6X]

Next time I experiment with this filament, I plan to put down some kapton over the PEI to give me a disposable build surface until I dial in the process. Maybe this filament will work OK with lower bed temperature... or maybe it just sticks too aggressively to PEI to use it on that kind of surface.

Hmm, I have dual extruders... maybe I should print this stuff on top of a raft of something else? I haven't gotten the hang of dual extrusion yet, but I expect I will with more experience.

[Jules]

I'd just test with a smaller print first with that filament....large surface area prints are a beeyatch to get off sometimes, even when the filament doesn't crumble when you try to remove it.