TAZ5 - PEI separating from adhesive

General LulzBot TAZ
1

Have previously replaced the PEI surface on the head bed with 0.060" PEI sheet attached to glass with new 3M double side adhesive.

After several lengthy prints (10-15 hrs), one side of the PEI is separating from the adhesive. This is causing the bed level adjustments to get totally out of whack. Any suggestions or recommendations on better adhesion? I have another PEI sheet and 3M adhesive sheet that will allow me to change out the PEI on the build plate. When done previously, I thoroughly cleaned the class prior to setting the adhesive in place. The PEI protective film was removed and immediately the PEI sheet placed upon the adhesive. Then reinstalled the build plate in the machine.

Should the build plate be placed into some type of compression to “push” the PEI onto the adhesive more firmly?

Thanks,

Wayne
Oklahoma City

2

There are higher temperature rated adhesives out there, the issue at that point becomes one of ability to ever remove the PEI sheet. With the 3M adhesive you can still remove and reattach the PEI sheet. With one of the higher temperature rated adhesives likethe 3M 9082 High temperature adhesive tape or Loctite 9340 high temperature epoxy, that PEI sheet is never coming off. The problem with those also is we don’t know if they conduct heat well enough to work for our purposes.

To get a better initial adhesion, you can vaccuume bag the bed if you have an air compressor. Install the new sheet as normal taking care to eliminate air pockets, then bag the assembly and place under vaccume until the adhesive has reached full working strength

3

As I recall, when the bubbling PEI issue first came up, I saw a mention in this forum from a factory guy that they’d had to add a “bake-out” procedure with the build plates to improve things.

I’ve begun doing something like that, myself. Here’s what happened to me:

I had a bad PEI bubbling/blistering issue with my TAZ5, it was one of the fairly early ones. Lulzbot, with their usual great customer service, sent me a new build plate ASAP.

I should mention that, looking back, the blistering on my original build plate only started getting bad after I’d let the printer sit unused for a week, then began using it again.

Anyhow, when I got the new build plate I installed it and did a test run up to 110 C (I mostly do ABS), and there was no blistering. Then I didn’t touch the TAZ for two weeks, due to some family obligations that had come up.

During that period it was hot and very humid here, unusually so for southern California.

Then when I turned it on for the first time after not using it for that two weeks, I immediately saw that the PEI was starting to blister!

Thinking about it, my assumption was that it had absorbed humidity from the air during those two weeks. So I started by warming the plate to 30 C for a day, and saw no problem. Then I took it up to 40 C for a day, and saw no problem. I repeated that process in 10 degree steps, giving it around 6-8 hours minimum at each temperature, until I got it up to 110 C and there was still no problem!

In effect, that was two tests on two different build plates, with the same result: A longish period of inactivity in a high-humidity environment resulted in blistering. And ever since, I run the plate up to 50 degrees or so for four hours or so, if I haven’t done anything on the machine for a few days, just to keep it dried out.

Doing that, I’ve had zero problems with blistering. And that’s with the replacement plate that had started to blister when I first ran it after two weeks of non-use.

So read into that what you will, but I believe that moisture is absorbed into the adhesive layer, at least partly through the PEI but also along the edges since the problems generally seem to start around the edges.

And my experience says that warming the plate to 50 C or so for a few hours every few days of non-use will keep the problem from coming back.

For folks who print with PLA, it’s probably less of a problem. Maybe in drier seasons or locations it’s not a problem. In winter, when the heater runs a lot, it’s probably not a problem, for instance.

Anyhow, you might try an approach like that, especially after putting on a new PEI layer, to see if it helps.

4

I think it’s humidity absorbed into the adhesive as well. I’m on my third bed. The first I didn’t know what to look for. The second looked bad, I could tell it would bubble and separate. The third plate looks good. Any bubbles looked as though it was related to the silicone heater pad.

With the third I’ve sealed the edge with silicone. Been careful to let cool to 50C. Have a dehumidifier in the room to keepat 40%. If it happens again, I may try LB support… But more than likely I’ll look to removing completely and going to a removable bed.

Always give support a call first… They are really good about this issue.

5

Humidity may be the root cause of the separation. Today when printing (machine is in my garage, in an enclosure) the rain was falling outside. Looking at the weather station at 8 pm CDT, the humidity is still greater than 99%.

I’m going to try the preheat process for a period, then let it cool, and follow up with sealing the edge of the PEI to the glass plate with silicon.

I’m sure the original build plate and PEI would have been covered under warranty. But. I didn’t even inquire since it was my actions that damaged the material. I pulled a chunk out of the PEI one day after printing. I apparently tried to separate the ABS piece from the PEI before the temperature had fallen off sufficiently. I was using the clam knife supplied in the tool kit and proceeded to cut a 1/2" by 3" chunk of the PEI sheet.

From links found on other posts on the forum, I ordered the 0.060" PEI sheet and the 3M adhesive (DigiKey and McMaster Carr). The original PEI was maybe only 10% the thickness of the 0.060 sheet I installed, very thin in comparison. ABS prints just almost don’t want to release from it.

From a newby stand point, the TAZ5 machine is pretty fool proof. I did have a power supply failure which Aleph replaced, thank you! Print problems have been mostly self inflicted. I’ve been driving the TAZ5 with a laptop computer. Windows updates really irritate me in that I have had a couple instances where the print is going flawless, then, the computer reboots! So, any print taking longer than an hour to build, is printed from the SD Card eliminating the pc…

Thanks all for the insight!

6

FYI my Shop computer with Windows 7 the power saving and Windows update are both turned off. About once every 2 weeks I let it do the Update thing.

7

This has been discussed over in the mini forum:

https://forum.lulzbot.com/t/heated-bed-delaminate/2073/1

Yes it is humidity trapped in the PEI. Lulzbot now bakes their PEI before adding the adhesive and it seems to be much improved. I’ve gotten a replacement bed and it’s done quite well. At least better than the old bed. You can call Lulzbot under warranty and they will send you a completely new glass bed with heater and PEI no questions asked. Takes about 10 minutes to install.

Give Lulzbot a call and they’ll take care of you.

-Jim