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Bed material questions (PEI vs. Kapton)

Posted by Praeitas 
Bed material questions (PEI vs. Kapton)
May 11, 2015 09:16PM
Hi- I've been lurking for a while, but haven't really needed to post, but now have a few questions about bed materials.

EDIT: I forgot to mention that I print in just about everything. Mostly in ABS, but also dabble in PLA, and have been advancing into nylon and HIPS, as well as into polycarbonate, eventually.

Okay, so for reference, I've been using ABS slurry and have been wanting to get off that and onto kapton for some time. Being researching various things, and I'm seeing people recommending PEI, as well. (Lulzbot, for example, includes that on their printers. A friend of mine has one for work.) I'm looking specifically at the 12x12x.04" sheets of PEI and the 12x12 x.05" kapton.

First question is, has anybody done both? is there a significant difference? is there even a clear 'this is the best ever, so far' option? The internet is as usually murky on this point. so... what are the trade offs between them? Will either of them wear out and tear with parts coming off? (or is it just when crap happens and the nozzle drags?)

Secondly, is there an advantage to buying the kapton without adhesive, and gluing it oneself? I assume it needs something.

Finally, and this is more a matter of curiosity than anything else. Has anybody tried using a film of cured epoxy? I happen to have some on the shelf, for various projects. it seems like it would be an easy-to-apply treatment that would be fairly durable. Adhesion, though, might be another matter. have to assume I'm not the only one who keeps the stuff on hand... if it occurred to me to try it, I'm guessing somebody already has.

And thank you for your help. As I've said, I've been lurking for...well a year or two now... most the answers I've been able to find on the wiki or with a bit of a search on the forums. this website should be a national treasure. But if it were, the gov't would probably ruin it.

Edited 1 time(s). Last edit at 05/11/2015 09:35PM by Praeitas.
Re: Bed material questions (PEI vs. Kapton)
May 11, 2015 10:05PM
I'm interested in PEI, too, but only have experience with Kapton tape and ABS.

I use 6 strips of 5 mil thick x 2" wide Kapton tape to cover my 12" x 12.5" bed. I replace only damaged strips as needed, and the 5 mil stuff is very tough so it rarely needs replacement.
I can't imagine there would be any advantage to glung it down yourself- the tape comes with high temperature adhesive that is uniformly applied- I think you'd have a hard time keeping the surface flat if you apply your own glue.

My printer has the kapton applied directly to the not-easily-removed aluminum bed plate and removing large prints can sometimes be a struggle. A lot of people put the kapton on a glass or other substrate clamped to the bed and then put the substrate and print into a freezer to make release easier. I can't afford the extra mass that a glass sheet would add. Some people use hairspray, gluesticks, etc. but I don't want to gunk up my printer with that stuff.

Print adhesion isn't perfect with kapton- sharp corners can still lift a little bit so you still have to use brims and rafts occasionally depending on the shape of the part you're printing.

Edited 1 time(s). Last edit at 05/11/2015 10:06PM by the_digital_dentist.
Re: Bed material questions (PEI vs. Kapton)
May 11, 2015 10:27PM
I originally used Kapton tape. Found a 4-inch wide role on ebay and still have it. There are instructions somewhere for putting it on the glass using the soapy water method. Worked well although very tricky to put on without bubbles. My second printer was a Printrbot. That printer came with a fairly thick piece of Kapton that covered the whole bed. Was much easier to install than tape and I ended up ordering a piece of it from them to use on my third, homebuilt printer. It is a bit more expensive but is very long-lived and I highly recommend it. Haven't tried the PEI yet, although I do have a piece of the thicker stuff waiting around. In either case, I wouldn't recommend trying to glue it yourself. It is hard enough to put on with the adhesive pre-applied. I still use a layer of aquanet over the Kapton for printing. Have not had great luck with the spray directly on glass.
Re: Bed material questions (PEI vs. Kapton)
May 12, 2015 02:38AM
Finally, and this is more a matter of curiosity than anything else. Has anybody tried using a film of cured epoxy?

AFAIK, Epoxy sweats out some sort of oil, making it hard to glue anything on it permanently.


this website should be a national treasure. But if it were, the gov't would probably ruin it.

Well, it´s a mondial treasure! No local gov´t can ruin it winking smiley
Re: Bed material questions (PEI vs. Kapton)
May 12, 2015 02:53AM
I'm printing on PEI now for a few years. It is perfect for ABS and works fine for most other materials. The biggest excpetion is Nylon. Nylon only works for me on either glas+glue (only for smaller parts though), or on fibre boards like Garolite/Tufnol. On Tufnol it sometimes sticks so strongly that you can't get it off without damaging the part.
Some elastic materials work better for me on glas+glue than on PEI, but not by much.

Re: Bed material questions (PEI vs. Kapton)
May 13, 2015 02:58AM
I've used both Kapton and PEI. After switching to PEI there's no way I'll go back to Kapton. Mostly I'm printing PLA, but I've had success on PEI with ColorFabb XT (PETG?) too. I've got some other filaments (like T-glase and NinjaFlex) that I'll get around to trying eventually too. I've not tried ABS and probably never will.

The only learning experience I had to get over with PEI is that the actual surface needs to get quite hot to get good adhesion. According to my tests and recollection, you need to get the top surface of the PEI to 70°C, or higher.

The one failure I've had so far with PEI is HIPS. I recently bought some Hatchbox HIPS that was labeled "HIPS for PLA" (which was the combo I planned on using). It's doesn't stick to my PEI at all. Then again, it didn't stick to glue stick, blue painters tape, or a raft of PLA either, so I'm suspicious that this HIPS might be garbage.
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