Anyone Tried a Removable PEI Bed?

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ttabbal
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Re: Anyone Tried a Removable PEI Bed?

Post by ttabbal » Mon Jan 02, 2017 8:39 pm

And I thought that the 40mil I recently installed was thick... :)

robajohn
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Re: Anyone Tried a Removable PEI Bed?

Post by robajohn » Tue Jan 03, 2017 10:36 am

Amazing this topic bubbled to the top as just this weekend I started getting bubbles!

I used an #11 exacto and poked the bubbles and squeegeed them back down same as I would on RC aircraft covering. I have no doubt that is a temporary solution though. But I sure learned a lot reading this thread!

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i-t-w.com
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Re: Anyone Tried a Removable PEI Bed?

Post by i-t-w.com » Tue Jan 03, 2017 6:03 pm

At some point LulzBot R&D experimented with 1/4"?? thick fiber reinforced ULTEM (PEI). We have a couple of the 12" square sheets if someone wants them. They're not pristine, but the price would be low.
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KFayal
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Re: Anyone Tried a Removable PEI Bed?

Post by KFayal » Sun Feb 26, 2017 2:43 pm

I'd like to chime in here on this thread. I keep hearing that PEI bubbles are the fault of the operator, but I can attest that I have had 2 build plate replacement by LulzBot (thankful for that) where the bubbles are happening in a circular pattern on the outer edge of the build plate. Both times (and now a third) the bubbles are in a big ring pattern in areas where I don't even print. I'm attaching a photo that I sent to the support folks. All three of the build plates I've had are doing the same thing. I don't know why, but maybe it's the amount of printing that I do, the length of the prints, I don't know. In any case, now I've got the same thing cropping up again and I'm considering the BuildTak Flexplate system with maybe a thicker PEI.
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20160216_113647.jpg

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CoParaTech
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Re: Anyone Tried a Removable PEI Bed?

Post by CoParaTech » Sun Feb 26, 2017 4:27 pm

I think bubbles are inevitable no matter how careful you are. I also think it depends on the shape of objects that are printed, the bed temp, and the type of filaments used. I have gone through probably 6 PEI sheets in a few years. But I print fairly large flat bottomed objects daily with bed temps of 70-105° C. After a few months, bubbles will start to appear near the edges of the parts and sometimes under them. I think the 3M adhesive just breaks down with heat over time and and the thin PEI just flexes where the adhesive fails as the parts cool and pull on the PEI surface. Going with a thicker PEI may be a viable solution. Perhaps I'll try that next time around and see how that goes.

robajohn
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Re: Anyone Tried a Removable PEI Bed?

Post by robajohn » Sun Feb 26, 2017 6:50 pm

Hey guys, FWI- maybe I am too dumb to know better (it happens far too often) but I have had excellent luck simply "popping the zits!" :)

I used the provided X-acto knife and just placed a few parallel cuts in the PEI. Since it is glass underneath you don’t have to worry about going too deep! Then I took the edge of my spatula and squeezed the gas out and pressed the sheet back down. I added cuts as needed for any stubborn pockets of gas. Then buff with the 3000 grit. I have had to do this on 5 or 6 spots on the bed.

I did this over a month ago and it has worked out very well.

In the first picture I had made the cuts and let the gas out before I took the first picture so you don’t really see the big bubble I started with but it was bad I promise! I took pics of this one because the other areas I "fixed" this way are hard to see.

Initial cuts in the bubble...
20170226_183453.jpg
Using the spatula to get the gas out and stick it back down....
20170226_183508.jpg
Ready to buff it out with emory cloth/3000 grit paper…
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20170226_183520.jpg

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CoParaTech
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Re: Anyone Tried a Removable PEI Bed?

Post by CoParaTech » Mon Mar 20, 2017 7:13 pm

Well, I snagged the thicker 40 mil PEI from CS Hyde and man what a difference! After installing the PEI sheet on the bed and putting it on the bed frame, I had just the right size washers laying round to put under the Bed Leveling Washers to compensate for the increased height and I didn't have to change the screws. So I tweaked my Z offset a bit, but not much, and have been printing for 3 days straight with my worst PEI torturing parts and I must say I'm impressed. The PEI doesn't stress at all and it is handling high heat without breaking a sweat. We'll see how I feel a few months down the road when it gets around the time the stock PEI sheets always failed (actually I think it was the adhesive that failed, not the PEI), but this thicker PEI is much stronger and I didn't have to change any temp settings. So for you guys (like me) that are tired of the bubbles under your PEI, you might want to give this a closer look. They have the stock size for the Mini (6.6875" x 6.6875") and I think Taz too. The Mini version in 40 mil is $17.87 with 3m adhesive sheet already mounted.

http://catalog.cshyde.com/viewitems/3d- ... /ultem-pei

doenute
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Re: Anyone Tried a Removable PEI Bed?

Post by doenute » Thu Apr 27, 2017 7:46 am

I have to agree with Suntorn's method earlier in this thread--good system They 1/8" PEI is excellent when laminated with the standard 3M tape to same glass. There are MANY air voids under the PEI, but there is no way they can turn into "blisters" with any kind of height that would effect printing due to the thickness of the PEI itself. Just give it a couple minute extra to let the heat soak through it before printing.

I went ahead, at the same time, and made the bed a two part system per the Lulzbot development--heater pad laminated to spring steel then glass/PEI lamination simply resting on top. Seems to be working just fine for me, but I am not pushing the envelope of heat sensitive materials with adhesion/warp problems like Nylon etc.

Is it perfectly flat--no. Is it better than printing over top of blisters and bubbles--yes.


BTW, I also purchased a 1/4" sheet and it is too thick. Due to differential heating of the profile, it simply curls up on the edges. Flip it over and it does the same thing on the other side. Goes back to flat without heat. I think the best compromise is the 1/8".

Daniel
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Re: Anyone Tried a Removable PEI Bed?

Post by Daniel » Wed May 24, 2017 5:57 am

Here is an update, I really love myy system now (removable PEI bed), I tried a 0.03" form Amazon instead of the 0.04" from McMaster Carr, it's much better, more flexible. Installed since months, it still looks like a new, no buble at all. I think I got the best setup now !

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