Bad Prints when steel sheet is flipped
When I got my printer, I had some minor troubleshooting to perform, but I got some very good prints, very quickly.
Levelling and adjusting the Z axis for a good squish was a painless process.
When trying to pry off a print that was stuck on the bed, I ended up with a nick in the PEI coating of the bed. The nick is right in the center, so that line will show up in any item that gets printed there.
No big deal- I will simply flip the bed.
As soon as I did this, I am no unable to get a clean print at all. The extruder ends up just squirting and dragging filament all over itself when it gets to the front of the bed. The test print for first-layer squish has rounded corners (poor bed adhesion) all the way up to the small test square, at which case the item turns into a filament explosion. It's not simply over-squished a little; the filament starts curling around the entire extruder.
Flipping the bed back results IMMEDIATELY in crisp corners and a nicely smushed bed.
The auto bed levelling is done without the steel sheet- is it possible that my sheet is warped in such a fashion that it's bowed in one direction? What would be the best way to approach this and diagnose what's going on? I would expect that if the plate were dished, I'd end up with issues on one side of the sheet near the front and back of the sheet, and the middle would print ok- but the other side of the sheet would be ok in the outer edges, but poor in the middle. The Left/right aspect of the sheet would be reversed.
I've wiped both sides down with alcohol and they appear clean. I don't think that poor adhesion would account for the birdsnesting, but I could be wrong.
I didn't see any suggestions yet for "one side of the spring steel prints better than the other". Any thoughts appreciated.
Re: Bad Prints when steel sheet is flipped
Clean the sheet.
In a sink, wash with a good dish detergent like Dawn, use a fresh paper towel as a wash rag, and only a few drops of soap. At this point never touch the surface of the sheet with your hands (seriously, edges only). Rinse in the hottest water you can get, use a fresh paper towel to help get the soap and other surfactants off. Dry the sheet with a fresh paper towel. Handling by the edges, move the sheet to the printer, desired side up. With fresh 90%+ alcohol, and a new paper towel (and clean hands), pour a cc of liquid on the bed and wash the bed with the alcohol (scrubbing is ok). Dry with a fresh paper towel (don't let the alcohol evaporate).
Now, with a small fresh paper towel, splash it with alcohol so it's damp, then wipe across the sheet as if painting it top to bottom with the alcohol. The alcohol should be evaporating as you wipe. If you see streaks ... go back and try washing again because you didn't get all the finger prints off the first time. No streaks, and you are ready to print, usually.
Once in a while you need to scrub the PEI with acetone to remove hard oxides that collect; and essentially refresh the surface. A fresh paper towel, wetted with acetone, and scrub the surface. You may see a whitish residue form. Some of that residue is PEI, so not an everyday cleaning. I do a second wipe with acetone like I am painting the sheet. This pulls up most of the residue. I sometimes resort to another alcohol wash if I think more residue needs to be lifted.
Anyways ... https://www.sciencedirect.com/science/article/pii/S0141391013002395 or Google "polyethylene oxidation" for more info.
Re: Bad Prints when steel sheet is flipped
I'll give it a shot. I've thoroughly scrubbed it with isopropyl, but haven't done the Acetone or dish soap yet.
The problem seems more physical than just poor adhesion. When it's birdsnesting at the front of the sheet, but not being squished at the back, it feels like a bad levelling issue- but one that I'm not sure how to correct.
Re: Bad Prints when steel sheet is flipped
Sometime isopropyl isn’t enough
i3 Mk3 [aug 2018] upgrade>>> i3MK3/S+[Dec 2023]