Sanding PEI

Because I can’t get ABS to stick on stock Taz 5 bed. (PLA is fine though)

Alright so I’ve read through a bunch of the stuff on the forums and far as I can tell the only thing left to try is sanding the bed.

Clean bed religiously with isopropyl alcohol✓
Verified 110C bed 240 Hotend✓
Cardboard enclousure✓
Z axis? Smush? Measured plus the bottom of prints are near flawlessly smooth✓
First layer set to 200%✓

So I’ve read suggestions of anywhere between 500 grit and 5000 grit. I have 1000 grit. Any reason I shouldn’t use that? The thought of sanding the bed makes me uncomfortable so I just wanted to get some affirmation from those more experience than I before I fully commit.

Secondary question, does anyone use acetone/abs slurry on PEI? From what I understand ideally, it shouldn’t be necessary, but just curious if there is a reason to actively avoid using it? What about glue sticks?

Theres always the Aluminum bed plate!

If I sand PEI, I use 1600 grit sandpaper. You are just knocking the shine off of it, removing any oil, and roughing the surface a bit. You aren’t taking much off. just enough to dull the surface a bit.

ABS slurrey contains acetone. Some people have reported plastic surface cracking and crazing when applying cold acetone to hot PEI. I’ve never seen it myself, and PEI is not soluble in acetone, so it shouldn’t be a concern, but Lulzbot Officially Reccommends Against It.

I had good results with a “Magic Eraser” sponge. Not sure if the material is hard enough to actually be buffing the PEI, or if it just did a thorough cleaning, but I went from non-sticky to plenty sticky using it with some water and a bit of denatured alcohol. I didn’t use much pressure. The PEI surface doesn’t look different from before - no swirling, etc.

I usually only sand the PEI to remove PLA that is left from printing with it. I use 1500 or greater to just knock off the edge of shine of the bed. I also only use glue sticks to prevent certain materials like Polycarbonate and ninjaflex from bonding to the bed surface. I have not had a time that I needed to use the ABS slurry for any reason.

Piercet are you saying there is always the option to buy an Aluminum bed and replace the glass/PEI stock bed?
If I sand it I def want to be as conservative as possible. Just enough to slightly rough up the surface. I’ll probably just avoid acetone then. Piercet what do you use when printing ABS?

hrabbot, you got ABS to stick on PEI just cleaning it with a magic eraser and alcohol? Thanks maybe I’ll look into that before I try sanding.

For the record, I’m trying to print out the large herringbone gear with Esun ABS. It lifts up high on the sides after just a couple layers, and if left long enough the whole thing will start sliding around the bed.

Yup, well, make one anyways. You need a 3/16" thick 12" x 12" plate (sourced from Ebay), 4 modified bed corner pieces (sourced from thingiverse a new heating element (lulzbot sells them when they are in stock or you can peel the existing one of the glass) and a new PEI sheet with adhesive or a Buildtak sheet. You put the PEI on top of the aluminum, stick the bed heater on the bottom, print the new corner pieces out with heat set inserts (M3, from Mcmaster Carr) and put it back in place and re-level. The huge advantage the aluminum sheet gives you is even and constant heat across the entire build platform surface. The glass tends to have a hot spot in the middle and colder edges. The aluminum bed plate mod, coupled with the X and or Y axis openbuilds extrusions, make for very well adhering prints.

Ya I noticed the uneven heating on the bed with an infrared thermometer. I don’t know what you mean by “the X and or Y axis openbuilds extrusions” though…

I use a Mr. Clean Magic Eraser sponge dry. Once with some IPA, but it made the PEI too sticky for ABS. with the dry sponge, it can be done while bed is hot. With the IPA do it with the bed cold. The sponge doesn’t hurt the PEI, but the slight grit removes oisl and residue from the surface as mentioned above.

Check the comprehensive taz modifications thread in the taz hardware subforum. Or take a look at my thingiverse profile under “piercet”