PEI surface without adhesive?
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I plan on upgrading my delta's print bed with the following stack from top to bottom: (optional) insulation -> 240V silicone heater -> 6mm aluminium tooling plate -> PEI surface. In my current setup there is a glass plate in the mix, on which the PEI is stuck to with the usual 3M adhesive.
My question is whether I can drop the adhesive (and glass) and put it straight on the aluminium heat spreader? I was thinking about some locator pins/holes to keep it in place. Any thoughts? -
I'd be concerned it would not stay flat as parts heat and cool on it?
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@bearer said in PEI surface without adhesive?:
I'd be concerned it would not stay flat as parts heat and cool on it?
That's what I am having trouble estimating. No clue if it would become an issue or not
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The idea is to have a removable print surface without going to magnetic surface route.
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I guess it would depend on the thickness of the sheet, you could just try heating it on the bed and see how soft it gets. A 120x120mm 1.6mm perforated PCB warps from the forces of a 40x40mm ABS part in my Up! Mini 2.
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@bearer I've never printed ABS, only pla/petg and tpu. By bed would be ~420mm diameter though
I've been looking for 500x500mm sheets and haven't found anything thicker than 1mm. Most commonly I've seen 0.2mm, which is obviously to thin in my case. -
Can't you just try it and then add adhesive if it doesn't work?
I am using 1mm PEI and I can't see how it would stay flat on my bed without adhesive.
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@zapta said in PEI surface without adhesive?:
Can't you just try it and then add adhesive if it doesn't work?
I am using 1mm PEI and I can't see how it would stay flat on my bed without adhesive.
The issue is that if it does not work without adhesive, I would need to come up with another solution to keep it removable. My current bed (~310mm dia glass+3M+PEI) already cools quite slow, the new setup would only add thermal mass so I decided I want something removable.
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But wouldn't you want rigidity while surface and part cools?
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@Nxt-1 Not sure if the frame permits it but how about simple clips like the overly used fold-back clips or something like in this (German) shop? There are variants that span 8+mm and would only take marginal amounts of space at 3-5 points around the perimeter.
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@nxt-1 said in PEI surface without adhesive?:
The issue is that if it does not work without adhesive, I would need to come up with another solution to keep it removable.
I am using this stack: insulation, 3mm aluminum with printed heater, adhesive, magnetic sheet, sprint steel plate, adhesive, 1mm PEI, and it works quiet well. Down side is that the magnetic sheet will lose it's properties if I will go above ~80C (at least this is what I heard).
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There are magnetic sheets that will work up to 120C if I recall correctly.
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@wilriker said in PEI surface without adhesive?:
@Nxt-1 Not sure if the frame permits it but how about simple clips like the overly used fold-back clips or something like in this (German) shop? There are variants that span 8+mm and would only take marginal amounts of space at 3-5 points around the perimeter.
That might actually be the most elegant solution if just the 3 locating holes and pins I planned are not sufficient.
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My concern was more that when it heats up it will expand and soften, making it difficult to keep flat in the center even if you pin or clamp the edge. But its an interesting approach, please do report how you get on.
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@bearer It will be at least a couple of weeks before I order all the materials, if not months. But if I have experiences to share, I will add them here
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@bearer said in PEI surface without adhesive?:
There are magnetic sheets that will work up to 120C if I recall correctly.
Very interesting link. Thanks. I plan to upgrade my bed to 5/16" mic-6 and may use this magnetic sheet.
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@nxt-1 I've tried exactly the same for my Wasp 60100 delta (60 cm buildplate). Got a 60 cm 1 mm thick sheet of PEI without adhesive and initially taped it down with kapton on the fringe. However, the PEI does warp when heated (even at 60C, more so at 100C) and not only pulled off the tape on the fringe but also bulged in the centre area. I then added spokes of double-sided kapton tape which mostly prevented the bulging in the centre:
But, even then, it still lifted off the kapton tape at the fringe by several mm after a couple of hours, which would ruin the very large prints I want to do. There might be better/smarter solutions using other types of tape (better adhesive) or other ways of placing the tape but at this point the work to tape it down sufficiently somehow is way too much work. I'm wondering if I should have gone with a much thinner sheet thickness b/c the warping is probably less (?) but I don't know how thin is still practical and I'm not about to spend another $150 to find out. No sure what I'll do with the 1 mm sheet I have but I either have to perma glue it to the bed or find a springsteel/magnetic solution for it ... -
I think it would work fine if the tape wrapped under whatever the PEI is sitting on. Just holding down flat like that requires very little force to peel it up.
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@charding said in PEI surface without adhesive?:
@nxt-1 I've tried exactly the same for my Wasp 60100 delta (60 cm buildplate). Got a 60 cm 1 mm thick sheet of PEI without adhesive and initially taped it down with kapton on the fringe. However, the PEI does warp when heated (even at 60C, more so at 100C) and not only pulled off the tape on the fringe but also bulged in the centre area. I then added spokes of double-sided kapton tape which mostly prevented the bulging in the centre:
But, even then, it still lifted off the kapton tape at the fringe by several mm after a couple of hours, which would ruin the very large prints I want to do. There might be better/smarter solutions using other types of tape (better adhesive) or other ways of placing the tape but at this point the work to tape it down sufficiently somehow is way too much work. I'm wondering if I should have gone with a much thinner sheet thickness b/c the warping is probably less (?) but I don't know how thin is still practical and I'm not about to spend another $150 to find out. No sure what I'll do with the 1 mm sheet I have but I either have to perma glue it to the bed or find a springsteel/magnetic solution for it ...Well that is exactly what I did not want to hear haha. Thanks for your experience.
I assume 'loose' PEI is off the table now sadly. The only alternative I can think off right now is to glue the PEI to a thin-ish flat aluminium tooling plate and consider that the removable part. The bed stack would become (optional) insulation -> aluminium tooling plate heat spreader -> aluminium tooling plate -> 3M -> PEI. I would hope to locate the alu/PEI combo in XY direction with locating pins/holes on the base heat spreader and unconstrained for the Z.
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Before I planned to use a 6mm thick plate as heat spreader. I wonder what thicknesses I should plan now. Maybe something like 4-5mm for the base heat spreader and 2-3mm for the part the PEI will be attached to.
I also wonder whether the base heat spreader still needs to be tooling plate and regular flat-ish aluminium will suffice. Any thoughts?
