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mhackney wrote:Read my looooong thread on PEI - it has a lot of info on the 3M adhesive and various techniques to apply it. http://forum.seemecnc.com/viewtopic.php?f=36&t=7452

Does the 'wet' application really work with the 3M adhesive? Just making sure I don't bugger up a $20 piece of PEI.

I have more sheets coming from Amazon after falling in love with my first sheet. But this time I'm not going to use glass, I purchased four 0.125" aluminum plates from a local supplier for $10 per plate cut to order from an industrial sized sheet of 6061-T6. The PEI is going right on top of the Al plate and I hope this cuts down on the loss of heat from the Onyx. I don't see any distortion in the flatness of the plates when checking with metal straight-edges.

Currently I have a thin surface thermocouple taped to the back of the Onyx in the center well near where all the cables solder on. This gives me the temperature of the back side of the Onyx so I know what my thermal fuses are seeing. I was surprised to see a 10 degree difference between the thermocouple and the thermistor, and another 15-20 degree difference between the thermistor and the surface temperature of the PEI. The glass, adhesive and PEI are not great conductors of heat. Hopefully the Al plate will help get the heat from the Onyx to the PEI and reduce the temperature drop on the surface. The enclosure is also helping lower the temperature drop between the Onyx and print surface.

Another funny thing I saw was the bed height changing while the bed was heating up. I manually ran the effector down to Z=0.5 mm and used feeler gauges as the bed heated up. The bed height swelled over 1.0 mm until it came to temperature where it settled back down. If I had a run-out dial indicator handy I would take a video of the dial to show it better. The good news is that this explains why I was having first layer troubles with the PEI at first because I was starting my prints too soon after the bed reached temperature. I don't know if the swell is due to the PEI-glass interface or to the glass warping or something else. If I wait 5-10 minutes after the bed comes to temperature to start a print I don't have the first layer blues.

Yes you can use the wet application but read my post from this morning. And you won't hurt the PEI. Worse case is you ruin the adhesive.

I lost my shirt a few years ago manufacturing .125" 6061 plates here. They ultimately warp. I refunded all of my customers including their postage. I have been experimenting with .25" mic6 ground plate. I hollow the back side to reduce mass. It works great.

timskloss wrote:

mhackney wrote:Read my looooong thread on PEI - it has a lot of info on the 3M adhesive and various techniques to apply it. http://forum.seemecnc.com/viewtopic.php?f=36&t=7452

Does the 'wet' application really work with the 3M adhesive? Just making sure I don't bugger up a $20 piece of PEI.

I have more sheets coming from Amazon after falling in love with my first sheet. But this time I'm not going to use glass, I purchased four 0.125" aluminum plates from a local supplier for $10 per plate cut to order from an industrial sized sheet of 6061-T6. The PEI is going right on top of the Al plate and I hope this cuts down on the loss of heat from the Onyx. I don't see any distortion in the flatness of the plates when checking with metal straight-edges.

Currently I have a thin surface thermocouple taped to the back of the Onyx in the center well near where all the cables solder on. This gives me the temperature of the back side of the Onyx so I know what my thermal fuses are seeing. I was surprised to see a 10 degree difference between the thermocouple and the thermistor, and another 15-20 degree difference between the thermistor and the surface temperature of the PEI. The glass, adhesive and PEI are not great conductors of heat. Hopefully the Al plate will help get the heat from the Onyx to the PEI and reduce the temperature drop on the surface. The enclosure is also helping lower the temperature drop between the Onyx and print surface.

Another funny thing I saw was the bed height changing while the bed was heating up. I manually ran the effector down to Z=0.5 mm and used feeler gauges as the bed heated up. The bed height swelled over 1.0 mm until it came to temperature where it settled back down. If I had a run-out dial indicator handy I would take a video of the dial to show it better. The good news is that this explains why I was having first layer troubles with the PEI at first because I was starting my prints too soon after the bed reached temperature. I don't know if the swell is due to the PEI-glass interface or to the glass warping or something else. If I wait 5-10 minutes after the bed comes to temperature to start a print I don't have the first layer blues.

I did it with the wet method on AL plate. I don't think I'm losing too much heat to the outside, but I definitely have more thermal mass than just the glass had (However, temperatures are very even, even beyond the heating coils). Be aware that the 3M adhesive, if you look at the data sheet, stick much more strongly to aluminum than to glass long term, and that is almost untouched by water and weak bases such as most soaps. I seem to recall something like a 103% adhesion rating after 24 hours immersion.

mhackney wrote:I have been experimenting with .25" mic6 ground plate. I hollow the back side to reduce mass. It works great.

Now that sounds like a lot of work and needing tools I don't have.

I tried my first Al plate tonight an OMG is the temperature even across the plate. Less than 0.2C difference over a 8 inch diameter, once you give it time to heat up. XC is right about the thermal mass. Once at temperature, the surface was 8-10 degrees below the Onyx temperature which is about half the temperature drop with PEI-on-glass. I'll try one Al plate with PEI until it warps, since I went through all the trouble already.

The funny thing is, I can never remember what the damn thing is called - my brain keeps wanting to call it a "donkey". I call it an "inverted index error".

g.

Hmm, reading up on your experiment Michael. I think the silicone paper soaks less than than the brown backing paper, but it will soak probably to much too. The key is to let the water residu vaporize before lifting the second backing. That takes a while, that's why I let it dry overnight. Warming it up like you suggested earlier will definitely help a lot. Signmakers are having troubles sticking signs to shopwindows for the same reason. The glass surface is highly unfriendly to any glue, especially when cold. Therefore most often they do this the dry way, without water. But for our purpose the glue film must be bubble-free and that is only possible after the wet-residu is gone which takes time. Try to preheat the glass to about 50C I think that helps a lot. But the soapy residu is in principle just a way to delay adhesion.

My 5 pack of 3M came today. It turns out you can not even get the brown side off first, it is more strongly adhered than the white paper. So I removed the white side, applied to my glass wet and I'm waiting for it to dry a bit before taking the next step. I did a quick test right after applying and I couldn't even get the brown paper to separate from the adhesive while it was still wet.

I found this as well. The brown side should stay on the adhesive. It's quite thin, like a sticky piece of saran wrap, so the brown paper is the only 'sturcture' that you'll have to lay it down with.

I found this as well. The brown side should stay on the adhesive. It's quite thin, like a sticky piece of saran wrap, so the brown paper is the only 'sturcture' that you'll have to lay it down with. I laid mine down with windex, and successfully squeegeed out the bubbles. Then I sandwiched it between a pair of Mic6 plates on top of my heated bed and put a 12" chunk of granite on top of it (an old Menards counter top display that's become quite useful)... Anyway, I baked it for about an hour at 40, and then for a while at 60, and called it good enough. Then I floated the piece of PEI on top of it, squeegeed the bubbbles out of that, and did the same sort of thing to warm and dry it. I'm pleased with the results. I also followed the edge of it with a razor blade to cut the PEI down to 300mm. That came out nice and clean as well.

[img]http://i.imgur.com/eyvKAlt.jpg[/img]

Now the problem that I'm experiencing is that the non-glass surface of the PEI doesn't trigger the accelerometer the same way and I'm failing calibrations. Any tips on getting that right?

[youtube]http://www.youtube.com/watch?v=JnlxawBHJxw[/youtube]
http://www.youtube.com/watch?v=JnlxawBHJxw

I'm struggling with that problem also. Still working on sensitivity and other settings to see if there is a solution.

mhackney wrote:I'm struggling with that problem also. Still working on sensitivity and other settings to see if there is a solution.

I flipped the plate over, ran the calibration against the glass without an issue 3 or 4 times, and flipped the plate back over. Printing now. So far so good.

Man, I haven't cracked a build plate in years. This stuff really sticks.

This happened after sliding that thin tool underneath the print to loosen it.
I didn't think I was being very aggressive with it, but I guess it was too much.

printing at 250c ABS on a 110c bed.

I'm guessing that I need to raise the z height a bit and/or lower the bed temps.

[img]http://i.imgur.com/wTv1Ab6l.jpg[/img]

I use a GeckoTec and I could not be happier with it. The magnetic base plate is about 6 mm thick and the build plate is another mm in thickness, takes a little longer than the glass does to get up to temperature and a while longer to cool down but it is worth it. Simple to remove PLA after it has cooled, I like it Have not tried it with ABS or PET filaments yet, I have some to test with but too busy printing with PLA at present.

@gestalt73 - if you broke that plate with PEI on top then you really were exerting a lot of force. You are also heating your bed waaaayayyyy too high. 70-80°C will do it.

@crocky, is GekoTek textured?

mhackney wrote:
@crocky, is GekoTek textured?

It has a coating on the build plate which does not be disturbed when you are printing to it, when the print is finished you just wait until it has cooled then you simply pull her of the build plate and if it is hard you can't remove the build plate off the magnetic base give a couple of small twists and it will fall off. For me it is a beaut device! No cleaning either so far...

I mean, is the surface textured and does it impart a texture to the bottom of the part? For me, this is a non-starter. PEI works exceptionally well and does not leave a texture and I can control whether it leaves a matte finish or glossy finish.

It's probably semi-gloss... The same finish as the build surface.

Anybody have luck playing with the accelerometer settings to make them work with non-glass surfaces yet? I was going to play with it, but didn't want to duplicate the effort if someone else has already dialed it in. My assumption is that I'll want the accelerometer to be more sensitive, right?

I have it working with Duet but not sure if or how that translates since some of the "magic" is in the probing control Duet provides.

This seems to be a fickle thing to repeat. Originally, I was having the probe point on the Y tower press too hard and disjoint my effector. It happened over and over and would never get past that point. About a week later, full calibration worked without an issue. Today, XYZ all work for the endstop offset, but the spot under the Z tower was causing issues. This makes me think that I'm right on the edge of what's an ok probing sensitivity.

I changed this value from 40 to 45. So far so good. I'll let you know if it goes haywire again.
[img]http://i.imgur.com/7TZx1Fz.png?2[/img]

I got my 3M sheets and PEI yesterday and are fiddling a bit with it. Like Michael already said, it is impossible to take off the brown backing paper first. It sticks way to much for that. The other siliconized white backing goes of easily, and my theory is... that there is a theory to it...

The glue film itself has totally zero structure to it. Essentially it has no form of it's own at all. So the structure has to be given by the backing paper. In order not to pull the glue loose from the backing, they have to make the second liner stick less significantly. So, in my opinion the white should go off first, then you have a sturdy brown craft backing that makes the "wiping the bubbles out" easy. After that you have to make very certain that the glue film is sticking to the glass/alu enough to be able to pull the backing off. So it is better to wait and let it dry longer than you have patience for

I have the 3M fixed to the glass absolutely bubble free now. Maybe later today or tomorrow I will try the PEI itself. I made some recordings of me in action. If it doesn't look to ugly I will share that later.

I ruined one adhesive sheet and got it right the 2nd time. I went overboard and let it dry for 3 or 4 days before I tried peeling the backing off.

g.

g.

I was able to get the brown backing off after about 2 hours of baking on the Onyx at 50 degrees. But barely, a small piece of glue film came loose at the outer perimeter of the boro. I just cut it away.

I do however get a funny misty white discoloration that appears to be on top of the PEI. But is not. It's in the glue film. It disappears under firm pressure but reappears after a while. Looks like it is chemistry between the glue and the application fluid I used. I have a fluid that is specifically intended for vinyl signage applications, but the 3M seems to not like it. Will see if it vapourises in time...

Correction... Instead of changing the max probing sensitivity, you need to change the actual sensitivity in the printer settings below. (for whatever printer type you have selected above)

Interestingly, lowering the sensitivity value seems to make the probe more sensitive. I lowered mine from 20 to 15 and haven't had a failure yet.

[img]http://i.imgur.com/AllTxYM.png?1[/img]

PEI works for me! ABS 235C/95c-300mm tall on a 22mm by 22mm raft. I could never do that with gluesticks.

[img]http://www.perrydice.com/images/20x20x300.png[/img]
[img]http://www.perrydice.com/images/20x20x300close.png[/img]

That's cool!