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Anyone Tried a Removable PEI Bed?

Posted: Tue Mar 22, 2016 10:56 am
by moejt
I have come to love PEI. A well maintained and well cleaned/sanded PEI sheet has unparalleled stick.

Recently I have been experimenting with other build plates such as Geckotek. I love the idea of Geckotek and its removable flexible plate but after the first few prints it loses its stick as the coating cures more. (I've been in contact with the creator Brad and the plate is working as intended and he is also seeing the adhesion issues that I am experiencing. Hopefully future versions will have the performance I need).

Anyways, So i'm back to PEI because I can obtain better stick. However I hate part removal of the PEI. I make and sell a lot of costume props which are required to look perfect, thus I need perfect bed adhesion. This requires me to often "over stick" a part on the PEI for large prints just so a corner doesnt warp slightly.

This isnt the problem... The problem is when you go to remove the part (yes I use proper procedure, IPA soak, I take my time and the bed is set between 50-60C). But even with the best intentions and being careful, you still end up with bubbling of the PEI sheet as it pulls. Not a major issue but man is it annoying.

All this to say -> PEI is the perfect build plate material except for its inability to stick well to its sub plate.

This brings me to my next idea. Why bother with adhesion? Has anyone tried to buy a 1/8" or 1/4" thick PEI sheet and use it as a removable bed? There would be no bubbling as the bed doesn't need to be "glued" down.

Anyone tried this? What would be the issues that you'd run into? Flatness? I've never messed with PEI in its raw form, I assume its pretty rigid? As in a 1/8" sheet would not flex (i've seen people talk about scoring and snapping PEI sheets). Why are more people not doing this?

Re: Anyone Tried a Removable PEI Bed?

Posted: Tue Mar 22, 2016 11:59 am
by ttabbal
I've been looking into it. I found some older forum messages on other sites talking about PEI being used that way. It sounds like there is potential for the bed to be a little less flat. That seems to be an issue with any removable surface though. I was going to try it, but the Zebra was a lot cheaper so I decided to give it a go first. It works well, but doesn't grab as well as PEI. I'm still planning to try getting a PEI sheet to use that way. I doubt 1/4" would be needed, 1/8" is probably more than you need really.

If you do try it, please post your experience.

Re: Anyone Tried a Removable PEI Bed?

Posted: Tue Mar 22, 2016 1:50 pm
by jballard86
ive purchased an 1/8 thick sheet with the same idea. It came warped. I attempted to bake it to anneal it in a way. to do that I clamped it between 2 aluminum plates and put it in the oven @ 350 for 3 hours, I then bumped up to 405 for 1 hour, lastly turned the oven off it took 16 hours for the assembly to cool.

At some point it cracked in 3 different places.

I ordered another piece, I have not yet tried to flatten it.

Re: Anyone Tried a Removable PEI Bed?

Posted: Tue Mar 22, 2016 6:14 pm
by moejt
I figured I wasn't the first who thought of this!

I looked into zebra plates but everything I read made it sound like they were more for PLA and ABS stick was "meh".

Geckotek is promising, and I think the typical user would probably be happy with it.

Jballard could you tell me who your supplier is? Maybe I'll try a different one?

Re: Anyone Tried a Removable PEI Bed?

Posted: Tue Mar 22, 2016 7:24 pm
by ttabbal
I haven't tried ABS, PETG works quite well. HIPS is a little iffy sometimes, but usually works well. It worked really well when I inadvertently used a raft.. :lol:

Re: Anyone Tried a Removable PEI Bed?

Posted: Tue Mar 22, 2016 11:19 pm
by kcchen_00
ABS works great on the Zebra plate. Set the heat bed to 70C, get the initial Z correct. I'd also recommend a lower extrusion temp for the first few layers... they recommend 230C, but 240C seems to be fine.

A PEI removable bed would be interesting. I've read the same posts about bowing of thicker plates. The sweet spot may be a little thicker than stock, using the 3M 468MP strips. The thicker sheet should spread the stress from print removal.

Re: Anyone Tried a Removable PEI Bed?

Posted: Wed Mar 23, 2016 3:43 pm
by jballard86
moejt wrote:I figured I wasn't the first who thought of this!

I looked into zebra plates but everything I read made it sound like they were more for PLA and ABS stick was "meh".

Geckotek is promising, and I think the typical user would probably be happy with it.

Jballard could you tell me who your supplier is? Maybe I'll try a different one?
I ordered from Amazon. I feel like this is going to be a reoccurring theme with thicker sheets of PEI.

A better idea may be to add a slightly thicker pei sheet than stock to an 1/8" substrate. if glass I would put the same sheet on both sides to try and counteract forces trying to break it. Think laminated glass.

To bad thin sheets of gorilla glass are really expensive, add PEI to each side of a .078" thick sheet would probably be incredibly strong.

Re: Anyone Tried a Removable PEI Bed?

Posted: Wed Mar 23, 2016 3:52 pm
by jballard86
im actually thinking that a 1/16 borosilicate glass plate with a 16g aluminum plate laminated to each side with a stock thickness pei sheet laminated to each side would hold up to the forces just fine, while also keeping weight down.

The lamination would add to the stiffness of the glass and should hold true to the straightness of the glass, if they could be bound together efficiently, without tape.

Re: Anyone Tried a Removable PEI Bed?

Posted: Wed Mar 23, 2016 6:44 pm
by moejt
Maybe, but I still feel like you'd have problems with the PEI coming free of the subplate. It all comes down to adhesive and maybe a better adhesive just needs to be used than what lulzbot uses with their PEI sheets.

Anyone know what lulzbot uses to glue their sheets to the plate? I feel like it's pretty lack luster, although I hear the issue is possibly more due to moisture during assembly?

A 1/8" sheet of PEI that is flat really would be the ideal situation (unless a flexible PEI "alloy" could be found, then that would truly be the Holy grail).

Is it the tolerances on the sheet that make it not flat? Or is it that it just bows? Wouldn't an even thicker PEI sheet fix bowing? So the issue would be tolerances. So the real question is - are flatness issues unfixable because they are caused by the material? (warps during cooling ect) or are is the issue with "poor" manufacturing process. Might be time to source another vendor?

Re: Anyone Tried a Removable PEI Bed?

Posted: Wed Mar 23, 2016 7:28 pm
by jballard86
i think it is just warped in general.

Binder clips would possibly hold it flat. my next post ill include a pic.