I love my Taz 5.
I have been printing PLA for a while now and the middle of the PEI bed is heavily used. I am finding my prints stick too well there. On the less used parts it sticks the perfect amount.
I tried some alcohol but it seems like it needs a bit of a harder clean. Any recommendations?
This could be:
In general adhesion to PEI boils down to the squash of the first layer (how close the nozzle is to the bed). An eight or sixteenth counterclock wise turn on the endstop should help. Use a business card as a feeler to check the nozzle height. For even more granular control of the nozzle height, use the z-offset to raise (positive value) or lower (negative value) the nozzle after homed… I find that .1 increments !take a big difference on the PEI.
To cure the sag, folks have replaced the rods and bearings with hardened rods and metal bearings.
You might try a very light sanding with very fine sandpaper to scrub off some of the PLA on the bed.
Just an Idea.
Thanks.
I’ll go with a through clean. I have been light so far.
Then measure as I have a rig that is super accurate and then sand last.
Much appreciated.
I am going to try sanding the center part to clean it a little. Nothing else worked.
Report back… Sanding usually increases adhesion.
I think you need to increase the z-stop.
I tried bed stop and bed leveling. It only sticks in the most used parts of the bed. I think it is ‘gunky’ there. I’ll try scraping it down.
I don’t know enough about PEI to know what damages it.
Oils can render it somewhat useless. You can also break it if you flex it too much. I suppose you could accidentally gouge it removing a part. Aside from that it is fairly hard to damage. The biggest issue I have ever ran into was the sheet delaminating from the adhesive, but thats easy enough to fix.
I still think it is a build up of PLA, and I do not what if anything that can remove PLA and will not damage the PEI. So I would try to sand it a very little bit with very fine grit and see if it sticks less then.
I suppose a thing film of extruded filament could be left over from each print, but never seen it happen on my bed. Extruded material comes off with the project.
If parts stick too much, I raise the nozzle an eight turn. If the rest of the bed isn’t sticking as much, THAT’S the dirty part which needs cleaning. 
. A wipe down with isopropyl alcohol usually does the trick… Or a Mr. Clean Magic Eraser, which is just abrasive enough to remove oils.
Regardless, please report back… nice to file this tidbit about leftover material into the notes.
So the solution that worked best was adjusting the z-height. Making the first layer as far away from the bed as possible gave the best results. The first layer is like a layer of string and pushed on the bed with the smallest of force.
I’ve had that problem with PLA, too. Alcohol works best on ABS, not much on PLA.
On a particularly stuck PLA part with a large flat bottom, where alcohol had done nothing even overnight, what finally helped was to heat the bed up to 70-80 C. As the bottom layers started to soften a bit I could push a thin metal tool under the edge and start lifting it up, after which it came up fine.
I left the part on the bed as it slowly cooled back down,and the small “notch” I’d made in the edge of the bottom getting under it went away over the next 20 seconds or so, and the bottom was perfect.
I really like the PEI. Nozzle height is important for objects sticking… and staying stuck to the bed. With digital dial gauges, I’ve been able to quantify the Z value for what I think is optimal (my technical definition: object starts to snap and crackle at 60C, and pops off at 50C ). Then use the Z-Offset GCode to adjust “stick” based on size of object (larger object with a lot of surface area on bed, use .2).
For my dial gauge 18.25mm is perfect (zeroed when measuring pin is completely off the bed). YMMV, but highly recommend taking the guess work out of “figuring” out the nozzle height with the digital dial gauges.
My original PEI sheet ripped and a section came off with a large flat ABS print. The replace sheet I got is 1/8", so it won’t tear. I have the same issue where the middle of the bed is much stickier, and has a visible haze on it. Acetone wipe down until paper towels no longer get discolered seems to work pretty good. Limonene works for HIPS, but I don’t know what disolves spaggetti. PLA is a form of pasta, isn’t it? Hey, are PLA prints right is they stick to the fridge?
David
Try some fine sandpaper to re-vitalize the PEI. My personal method is to use a Mr. Clean Magic Eraser… just enough grit to get rid of residue.
Don’t use acetone to clean PEI! It can glaze and cause cracking. Use isopropyl alcohol. A swipe with a wipe and you should be good to print.