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It is 5-6 times less thermally consuctive than glass

http://www.professionalplastics.com/pro ... erials.pdf" onclick="window.open(this.href);return false;

http://www.azom.com/article.aspx?ArticleID=4765" onclick="window.open(this.href);return false;


So making it too thick would not be beneficial. A higher bed temp may be necessary to get the same surface temp on the PEI or a longer dwell time (so a super super fast heated bed may not be an advantage here)

But then again, bot does it succesfully so obviouslt these can be overcome.

teoman wrote:My non windex single piece pei is also not sticking to the cracked pei

I run bed at 115 degs c. (Un verified with therocouple).

Not sure what you mean saying that your PEI isn't sticking to your PEI, but I also run the bed at 115. Maybe that's the ticket. The 3M tape can handle that short-term, but long-term it can't, and gradually releases?

Yeah, sorry, had a brain fart moment.

PEI is not sticking well to the glass, it is lifting off.

The 1st time when i heated up bed i got the detachment of sheet in exact centre.. The air inside grows so that it lifted around 3mm... I just took a needle and punctured the sheet...removed all the trapped air and pressed the sheet..From that day and now on no problem...

I have an 7mm^2 puncture but it still lifts up

Even though it will be a month or 3 before I am at the stage where I can be useful commenting on this or other topics I could not resist sticking my oar in.

bot wrote:

Holy1 wrote:

bot wrote: I designed custom clamps to hold all around the edges.

Did you want to share those clamps?

I just noticed your post now, sorry. I will definitely share the clamps, but they are for a very specific design, and are cut on a CNC router table, so I'm not sure how useful you will find them. I'll show you a picture. If you want them, let me know and I'll upload some cad files.

IMG_3682.JPG

I have just read through this thread and the sticky one on PEI and I am fascinated by the process and al the experimentation and your clamp is most ingenious . It would be a doodle for me to make something like this in my shop using something like 6061 T6 Al plate rather than the glass... and for the clamp ring as well the question will be how thick should I go on the Al I wonder if .25" would work with the Max heater; or if getting a high power heater and something like a .5 to even .75 thick Al plate would be best; I think I would also use a Al for the clamp ring as well. Oh just curious what thickness of PEI did you use? the .03"?

Windshadow wrote:Even though it will be a month or 3 before I am at the stage where I can be useful commenting on this or other topics I could not resist sticking my oar in.

I have just read through this thread and the sticky one on PEI and I am fascinated by the process and al the experimentation and your clamp is most ingenious . It would be a doodle for me to make something like this in my shop using something like 6061 T6 Al plate rather than the glass... and for the clamp ring as well the question will be how thick should I go on the Al I wonder if .25" would work with the Max heater; or if getting a high power heater and something like a .5 to even .75 thick Al plate would be best; I think I would also use a Al for the clamp ring as well. Oh just curious what thickness of PEI did you use? the .03"?

Surprisingly the clamp I'm using was cut out of .050” 2024-T3. It works very well. It obviously acts as a spring, and deforms slightly, but clamps nicely and evenly and only lifts up a tiny bit on the inside egde. If you'd like, I'll certainly share the files, but it seems you'd be capable enough to design your own if you wish. The PEI I used was 1/8" thick. Using the thin stuff requires it be glued down to a flat substrate. I don't like that, I prefer a thick sheet held in place by mechanical force.

I just ordered a 12" x 12" x 1.5mm sheet of PEI from these guys: http://spool3d.ca/" onclick="window.open(this.href);return false;
As well as a sheet of the 3M 468MP adhesive.
Nice to see a Canadian source since buying stuff from the US got too expensive lately.

I'm looking forward to not having to apply ABS juice or gluestick.

Jrjones wrote:I just ordered a 12" x 12" x 1.5mm sheet of PEI from these guys: http://spool3d.ca/" onclick="window.open(this.href);return false;
As well as a sheet of the 3M 468MP adhesive.
Nice to see a Canadian source since buying stuff from the US got too expensive lately.

I'm looking forward to not having to apply ABS juice or gluestick.

Thanks for the link! I have been using PEI for almost 2 years but I need some more for another printer and being in Canada is great.

Good prices on those too.

On the same site, they have buildtak at a higher price. Since it's more expensive, does that mean it's better in some way?

ramai wrote:On the same site, they have buildtak at a higher price. Since it's more expensive, does that mean it's better in some way?

See these links for buildtak and what other users think of it: http://forum.seemecnc.com/viewtopic.php?f=36&t=5236" onclick="window.open(this.href);return false;

http://forum.seemecnc.com/viewtopic.php?f=35&t=5555" onclick="window.open(this.href);return false;

http://forum.seemecnc.com/viewtopic.php?f=37&t=8787" onclick="window.open(this.href);return false;

bot wrote:

Windshadow wrote:Even though it will be a month or 3 before I am at the stage where I can be useful commenting on this or other topics I could not resist sticking my oar in.

I have just read through this thread and the sticky one on PEI and I am fascinated by the process and al the experimentation and your clamp is most ingenious . It would be a doodle for me to make something like this in my shop using something like 6061 T6 Al plate rather than the glass... and for the clamp ring as well the question will be how thick should I go on the Al I wonder if .25" would work with the Max heater; or if getting a high power heater and something like a .5 to even .75 thick Al plate would be best; I think I would also use a Al for the clamp ring as well. Oh just curious what thickness of PEI did you use? the .03"?

Surprisingly the clamp I'm using was cut out of .050” 2024-T3. It works very well. It obviously acts as a spring, and deforms slightly, but clamps nicely and evenly and only lifts up a tiny bit on the inside egde. If you'd like, I'll certainly share the files, but it seems you'd be capable enough to design your own if you wish. The PEI I used was 1/8" thick. Using the thin stuff requires it be glued down to a flat substrate. I don't like that, I prefer a thick sheet held in place by mechanical force.

I would enjoy seeing the file it never hurts to see how others solve problems... and right now I have yet to have an inkling of what my problems will be

Bot, how did you attach the clamp?

I just removed the cracked PEI (my mistake cracking it) and cut it in half, i used 4 binder clips? folder clamps? to hold it secure to my AL heat spreader. It was not lifting at all and it printed perfectly, but at the end of the print, the sides of the pei had lifted 2-4mm off the AL. Luckily the section with the part had not lifted so i got a good print.

How would I go about attaching the thicker PEI sheet to the bed?

Thanks in advance.

Here are the STEP files for the bottom and top part of the clamp. The bottom one has holes for the onyx's hole pattern.
The onyx is screwed to the bottom, sandwiching some cork and acrylic. The top clamp sandwiches everything together including the PEI, a mirror, and an aluminum heat spreader.

aah, but this is max metal specific?

teoman wrote:Bot, how did you attach the clamp?

I just removed the cracked PEI (my mistake cracking it) and cut it in half, i used 4 binder clips? folder clamps? to hold it secure to my AL heat spreader. It was not lifting at all and it printed perfectly, but at the end of the print, the sides of the pei had lifted 2-4mm off the AL. Luckily the section with the part had not lifted so i got a good print.

How would I go about attaching the thicker PEI sheet to the bed?

Thanks in advance.

On my Rostock Max, I just clamp the PEI and a mirror to the onyx bed like so:

Thanks for the pictures!

That is how i had imagined it, but seeing the thinner PEI bulge so much i had started pondering if there was something else to it.

Will the 3M Tape hold down a bulging PEI sheet?
I figured I would try the PEI by clamping it around the edges before taping it to the glass. When the heated bed was up to temp (100°C) I noticed that the middle was bulging up, and flipping it over would just make the bulge 'pop' to the other side.

After I let everything cool, the PEI is still bulged. Is the 3M tape strong enough to hold the PEI flat at temperature? I have 1.5mm thick PEI, smooth on both sides

Jrjones wrote:Will the 3M Tape hold down a bulging PEI sheet?
I figured I would try the PEI by clamping it around the edges before taping it to the glass. When the heated bed was up to temp (100°C) I noticed that the middle was bulging up, and flipping it over would just make the bulge 'pop' to the other side.

After I let everything cool, the PEI is still bulged. Is the 3M tape strong enough to hold the PEI flat at temperature? I have 1.5mm thick PEI, smooth on both sides

The 3M tape is strong enough to hold the PEI to the glass but the tape is not easy to work with without getting air bubbles in it.
At the beginning of this thread is a "sticky" by MHackney that provides tips on applying. The link is here: http://forum.seemecnc.com/viewtopic.php?f=36&t=7452" onclick="window.open(this.href);return false;

Jrjones wrote:Will the 3M Tape hold down a bulging PEI sheet?
I figured I would try the PEI by clamping it around the edges before taping it to the glass. When the heated bed was up to temp (100°C) I noticed that the middle was bulging up, and flipping it over would just make the bulge 'pop' to the other side.

After I let everything cool, the PEI is still bulged. Is the 3M tape strong enough to hold the PEI flat at temperature? I have 1.5mm thick PEI, smooth on both sides

Well the 3M adhesive is a lot stickier than I thought!

Printing a test piece right now to see how much better PEI is than ABS juice.

Let us know how it works out.

Jrjones wrote:

Jrjones wrote:Will the 3M Tape hold down a bulging PEI sheet?
I figured I would try the PEI by clamping it around the edges before taping it to the glass. When the heated bed was up to temp (100°C) I noticed that the middle was bulging up, and flipping it over would just make the bulge 'pop' to the other side.

After I let everything cool, the PEI is still bulged. Is the 3M tape strong enough to hold the PEI flat at temperature? I have 1.5mm thick PEI, smooth on both sides

Well the 3M adhesive is a lot stickier than I thought!

Printing a test piece right now to see how much better PEI is than ABS juice.

Eaglezsoar wrote:Let us know how it works out.

The PEI seems to work well for my smaller items, I first tried it with lower bed temperature settings as suggested, but I had better results keeping the bed at 110°, perhaps because this PEI is smooth (glossy) on both sides?

I still am having issues with levelling the printer to the bed, so I am limited to a small build area for now until I get something setup to work with openDACT.

mhackney wrote:Scrape it off with a single edge razor blade. I do think acetone will take off the tape residue too - but scrape first.

For the record, this worked pretty well. It took a little while to scrap off all the tape, but when I was finally finished there was actually very little residue that I had to clean up, the glass looked practically brand new.

I took the opportunity to order a replacement sheet of PEI rather than reusing the old one. My first sheet was from Amazon and worked alright, but didn't seem to work as well for me as for some others posting in this forum, so I decided to give McMaster a try.

It is a NIGHT AND DAY difference. The sheet from McMaster works much better and 20 degrees cooler than my previous sheet. My ABS doesn't curl at all and this morning I accidentally destroyed a part getting it off the PEI - it's that sticky. And hopefully now that I can run the new sheet cooler, the 3M tape won't release after a few months like it did last time.

Even if McMaster's a couple bucks more expensive and without free shipping, it is absolutely worth the difference in cost.

(Side note: Even trying the windex trick, I was still left with a zillion bubbles using my 1" strips of 3M tape. I think the 12"x12" sheet of tape is definitely the way to go from now on.)

I use PEI from both Amazon and McMaster with no problems. I do sand my surface with 600 grit (wet with a little water) to get a matte finish. This likely helps sticking too. But, the glossy side holds tenaciously as well. I also swipe the surface with isopropyl alcohol if I start to see any adherence issues. Finger print grease and other contaminants do affect this stuff too.