PEI bonded to Mic6

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pyronaught
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PEI bonded to Mic6

Post by pyronaught » Mon Nov 05, 2018 4:44 am

Anyone ever tried bonding a sheet of PEI to a an aluminum Mic6 plate to combine the benefits of both? When I say bonding, I don't mean the typical adhesive sheet holding the two together, which will always bubble and release over time and ruin the surface level. I'm talking about resin bonding with a high performance two part adhesive that will not allow local delamination the way adhesive sheets do. I've been doing this with good results lately and the difference between the thermal expansion coefficient of both materials has not been causing the plate to warp. You get the rapid thermal conductivity of the aluminum plus all the benefits of PEI: works on pretty much all filament types, tough as hell and doesn't scratch easily and does not require surface prep between prints.

We started doing a lot of TPU at work and the aluminum/hairspray wasn't cutting it for that. Our Mic6 plates get pretty gouged up from people not properly re-leveling or resetting the Z height after a change, whereas PEI is pretty tolerant of small amounts of nozzle dragging. You have to screw up pretty big to actually leave a mark, whereas the aluminum has zero tolerance for collisions. Hairspray buildup in the corners of our aluminum plates also happens due to half-assed cleaning between prints. The discipline required for Mic6/hairspray build plates just isn't there in our group of operators, so I went on a build plate search. I tried a solid 1/4" sheet of PEI just to see how that would work (it wan't my $100, so why not?). As you might guess, that stuff warps when heated up and the poor thermal conductivity makes a sheet that thick take forever to heat up. So if you've ever though of trying solid PEI, don't go there.

What has worked best so far is using an areospace grade adhesive called Hysol 9360 with glass beads to maintain the bond line, roughing up both the aluminum and PEI surfaces with 60 grit orbital sander, applying the adhesive to the aluminum and then sandwiching the PEI and aluminum together between two plates of 3/4" Mic6 in a press under 1 ton. I leave it in the press for 10 hours, then use an M2 to heat cure it at 70C for an hour. The press squeezes out all air and the glass beads create an even bondline without allowing every last bit of resin to be squeezed out. Now, the 9360 is very expensive at about $100 per tube and you have to have a gun that runs on comrpessed air to even shoot it. You can get about 4 or 5 plates out of one tube, so you would be looking at $25 just for the adhesive, $20 for the PEI and $50 for the Mic6. So it's a $100 build plate by the time you are done. We use the 9360 at work so I can get the leftovers for free, but someone else doing this might want to investigate lower cost adhesives. If you do use Mic6 and have some plates that you have gouged up pretty bad over time and can no longer sand the marks out, this is a good way to recover the plate back to something usable. It's a one-shot deal though, if you botch the bond line and get an uneven spread on the adhesive you have to throw the whole thing away and start over since you'll never get the PEI back off again. I've made 5 so far and only messed up the first one before I started pressing between the two 3/4" Mic6 plates to evenly distribute the pressing force without bending anything. I'll report back in 6 months after I see how they hold up over time.
Experience is what you get when you didn't get what you wanted.

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zemlin
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Re: PEI bonded to Mic6

Post by zemlin » Mon Nov 05, 2018 8:38 pm

I have considered trying some sort of bond, because you are right - the tape only works for a while. I have a PEI sheet now that needs to be re-bonded - not for an M2 though - it's 12"x12".

Needing heavier plates for clamping is also a deterrent for me ... just more $$$.

Sounds like you have a great solution though - the glass beads in the adhesive is a great feature for ensuring a good, even bond. I probably would have tried JB Weld first, but I have not tested it on PEI to see how it sticks.

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pyronaught
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Re: PEI bonded to Mic6

Post by pyronaught » Tue Nov 06, 2018 6:44 am

The thick Mic6 plates were something I pulled out of the scrap bin in the machine shop, so it didn't cost anything. They had holes in them but were still flat and served the purpose of even load distribution. But yeah, those plates are normally $100 each new so that would be $200 right there.

I did press one without the glass beads and that one turned out good too. The main key to having it turn out right is compressing between the two big Mic6 plates. Without beads you just have to be careful not to over press.
Experience is what you get when you didn't get what you wanted.

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pyronaught
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Re: PEI bonded to Mic6

Post by pyronaught » Fri Nov 09, 2018 6:01 am

Here's a plate after pressing. The excess PEI gets trimmed away on a band saw then the edges cleaned up on a belt sander.
IMG_0079.jpg
Here's the finished plate:
IMG_0080.jpg
Experience is what you get when you didn't get what you wanted.

makeal
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Re: PEI bonded to Mic6

Post by makeal » Fri Nov 09, 2018 2:15 pm

very nice

makeal
Posts: 63
Joined: Sat Aug 25, 2018 2:13 pm

Re: PEI bonded to Mic6

Post by makeal » Sat Nov 10, 2018 2:14 am

I would buy one if you have any extras

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zemlin
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Location: Indianapolis, Indiana

Re: PEI bonded to Mic6

Post by zemlin » Thu Dec 06, 2018 3:36 am

I've wanted to get some heavy plates for clamping build surfaces for a long time - today I finally broke down and ordered them. A pair of 12x12x3/4" MIC6 plates - from McMaster. I found they also have glass spacer beads - .01" diameter. A 1-oz size bottle for $11 - so I ordered those too. A little sprinkle of those should go a long way. I ordered a low-viscosity silicone that I'm going to test on the PEI to see if it bonds. Will also try JB Weld. If the Silicone bonds well I think I'll try that first as it seems like there'd be a chance of at least saving the aluminum if I wanted to replace the PEI over time.

jferguson
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Re: PEI bonded to Mic6

Post by jferguson » Fri Dec 07, 2018 10:35 pm

Hi Karl,
3/4 inch seems pretty substantial. Is this a thermal consideration? I stabilized the 1/8 inch aluminum bed on my TinyBoy by gluing 1/8 inch cork drawer liner under the heater element - or at least I think I did - it does work.

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zemlin
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Location: Indianapolis, Indiana

Re: PEI bonded to Mic6

Post by zemlin » Fri Dec 07, 2018 10:45 pm

jferguson wrote:
Fri Dec 07, 2018 10:35 pm
Hi Karl,
3/4 inch seems pretty substantial.
This is tooling for clamping to ensure flatness when bonded - not using it on the printer. My build plate is 1/4" - the thinnest cast plate available.

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