PEI print bed surface experiments

jdurand · Post by **jdurand** » Fri Jan 16, 2015 1:50 pm

I just ordered an aluminum sheet to put under my glass. I got one that's painted on one side, that can go down for insulation from the heater but would look better up. Maybe I'll just Kapton the bottom of it.

JFettig · Post by **JFettig** » Fri Jan 16, 2015 2:45 pm

I threw my sheet of aluminum directly on the bed. Didn't really think about it at the time but I haven't had any issues.

dunginhawk · Post by **dunginhawk** » Sun Jan 18, 2015 12:52 pm

so i cut a small piece and put it on my flashforge creator pro and its sticking great... now to test a large print

teoman · Post by **teoman** » Sun Jan 18, 2015 12:55 pm

How do you clamp down the aluminium, glass pei combo to the onyx.

On my last few prints it has shifted rather badly...

nitewatchman · Post by **nitewatchman** » Sun Jan 18, 2015 1:05 pm

I use the industry standard 3-D Certified Paper Clips (5).

teoman · Post by **teoman** » Sun Jan 18, 2015 7:14 pm

The ones that came with my kit dont fit anymore.

dunginhawk · Post by **dunginhawk** » Sun Jan 18, 2015 9:59 pm

So i attached my piece today, with 3m sticky (which is awesome, perfect)... but my first long print and visually (its still going) at least one corner is still peeling up...
230 c
100c bed.
lightly sanded the rough side.

should i run the bed at 110? maybe so.

mhackney · Post by **mhackney** » Sun Jan 18, 2015 10:02 pm

ABS I presume? Before ramping up the temp, make sure the PEI is COMPLETELY degreased and clean. I suspect they use some sort of release agent when they manufacture PEI and that seems to cause initial problems until the stuff is thoroughly clean. Also make sure your 1st layer thickness and calibration are good. PEI is not a silver bullet for improper machine setup.

dunginhawk · Post by **dunginhawk** » Sun Jan 18, 2015 11:11 pm

Yes ABS... I used a .2 first layer thickness, so perhaps that could be fixed by a .35 or something first layer.
calibration is tight.. very good... .
I do like the stuff... seems easy to use and quick nice. just hoping i can get it working 100%

dunginhawk · Post by **dunginhawk** » Mon Jan 19, 2015 2:33 am

so i just aborted a print (for other reasons) and tried to peel the first 3-4 layers off the bed and it was REALLY hard...
so here is what i inadvertently ended up doing.

1. Alcohol rubdown
2. ABS glue (too thick)
3. Scrape ABS glue off.
4. Acetone and scrape til it was clear.
5. Alcohol rundown.
6. Light sand.

Seems to be working. ill let you know in the morning after i kick off this last big print.

techstorage · Post by **techstorage** » Mon Jan 19, 2015 4:34 am

PEI Is in place, I purchased from McMaster Carr the 12x24 sheet and it is thin. The z adjustment made a small dimple and there is an air bubble by an edge. I looked at the order form and it is .003" not the .03" on Amazon.

Prints stay down well, but I don't know how long the thin sheet will last. Ordered the .03" on Amazon with more tape to be ready for replacement when needed.

mhackney · Post by **mhackney** » Mon Jan 19, 2015 8:48 am

You should always have a sheet of paper under the nozzle when adjusting Z with the hotend hot. PEI WILL melt and dimple if you are not careful. My first piece of PEI had 100s of Z adjustments done with it and no dimples, you just need to go slow and use paper and don't ram the nozzle into the PEI.

You might be able to sand the dimple out - or at least any raised edges around it. Once you have some experience on the PEI, remove it and flip it over to get a fresh surface. I recently did that without needing to retake. With the thinner material, it would be a lot easier.

The thickness of the sheet has NO EFFECT on its longevity. If you are scraping, melting and/or gouging a .003" thick sheet, you will do the same to a .03" thick sheet. I'd actually prefer the .003" and will use that the next print surface I make. It will transfer heat faster.

Dugginhawk, not sure why you put ABS glue on the PEI? In any event, it probably had the effect, along with the acetone rinse, of thoroughly cleaning the surface.

dunginhawk · Post by **dunginhawk** » Mon Jan 19, 2015 8:50 am

i did it because im still having major curling.. even after ALL of those steps, im curling...
I even did a brim this last print and there was just enough gap between the plastic brim and the print and it curled up...
im running 110c on my print bed... im so frustrated

dunginhawk · Post by **dunginhawk** » Mon Jan 19, 2015 9:06 am

any chance 110 for the bed is just too hot? should i back it down to 90 ?

mhackney · Post by **mhackney** » Mon Jan 19, 2015 9:07 am

I have to ask... Did you or are you running canola oil in your Bowden tube? You really should not have any issues printing ABS or PLA on good, can PEI. It really sounds like you have a contamination problem - ESPECIALLY if you abraded the PEI with some very fine sandpaper.

BTW, where are you located? Are you one of the guys up here in NE?

mhackney · Post by **mhackney** » Mon Jan 19, 2015 9:08 am

It is possible that too hot could be a contributor. I print ABS at about 80-85°C on PEI.

mhackney · Post by **mhackney** » Mon Jan 19, 2015 9:09 am

I also have to ask...

Are you using a fan? If so, when do you turn it on? Did the part start to curl before the fan came on? Are you running the fan at low speed for low airflow? Maybe take a look at strategy #12 in my guide (See signature).

dunginhawk · Post by **dunginhawk** » Mon Jan 19, 2015 9:12 am

No canola. No fan. No contamination.. pretty controlled environment.
I am actually In Des MOines IA, but work in Omaha, Lincoln weekly. (traveling IT sales).
Are you in omaha? next time im over that way id love to meet for a coffee or something.

mhackney · Post by **mhackney** » Mon Jan 19, 2015 9:15 am

No, I'm in Boston, MA - I thought you were from the NE.

Ok, that is just plain odd! We need to identify the variables. The 0.003" PEI is one. Can you send a link to where you got it? Perhaps it is a co-polymer or something and not the same material the rest of us are using.

Have you been able to print this part on other surfaces without curling? Did you post a photo or STL of the part?

dunginhawk · Post by **dunginhawk** » Mon Jan 19, 2015 9:23 am

This is the one i bought

http://www.amazonsupply.com/dp/B0013HKZTA

No. i havent been able to get it not to curl with anything ive tried. glass with hair spray, glue stick, glue stick liquid.

I cant share the STL file because its a customers. it is about 8x4x1.5 in inches... 20-25 infill,

mhackney · Post by **mhackney** » Mon Jan 19, 2015 9:42 am

Sorry duginhawk, I confused you with techstorage for a minute (he has the 0.003" PEI) - you have the same material the rest of us have used. Do you have shiny side up or matte side up?

Can you describe the print process...

does the first layer go down nicely and stay put when the 2nd and 3rd layers are printed?

At what point does the part curl?

Does it curl in the same place all the time?

Have you tried rotating the part in the slicer to see if the part peals at the same spot on the part or the same spot on the PEI?

Have you shifted the part along X or Y to move it off center to print at a different spot on the PEI?

dunginhawk · Post by **dunginhawk** » Mon Jan 19, 2015 9:49 am

Its too big to shift it, at an angle.. i can try turning it 180 degrees.
first layer goes down amazingly well... Best first layer ive ever printed.
Starts to curl around layer 20-40
seems to try to curl in each corner, not just 1.

mhackney · Post by **mhackney** » Mon Jan 19, 2015 10:08 am

Without a lot of data, what you describe sounds like shrinkage of the ABS. Have you tried putting a temporary aluminum foil enclosure around the part to keep the heat in (a makeshift heated chamber)? You can make several of these in incremental heights to add as the part increases in height. I suspect this is what you are experiencing. PEI is not magic, everything else has to work correctly too. Large ABS parts have a lot of shrinkage. There are many strategies to deal with that.

dunginhawk · Post by **dunginhawk** » Mon Jan 19, 2015 10:19 am

yeah, it makes me sad... i may just try a raft, a tall wide one... i just suck at raft settings to get them to come off easy with little artifacting.

dunginhawk · Post by **dunginhawk** » Mon Jan 19, 2015 12:41 pm

someone on the other board used this method for stemming the curling in the corners.
so im printing that right now to see if that helps...
[img]http://i1132.photobucket.com/albums/m562/dunginhawk/Capture_zpsab4cef3e.jpg[/img]

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PEI print bed surface experiments

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