Problems with first layer (retractions, overextrusion?)
I'm really not sure what's going on here. It was printing perfectly for a week and now I'm having problems on retractions, especially on the first layer or so. If I raise up the temps and babysit the first few layers, sometimes taking a few restarts, the prints still come out great.
The filament is "lifting up" on areas of retractions, and there is stringing occurring. This below is a z-calibration in PLA printed at the default 215 degrees:
You can see the print lifting up where there were retractions (seems like):
This is an example that looks fine except for a little strand that goes rouge at the edge of the print. The hotend has a tendency to grab on to there suddenly and drag the whole print loose:
I tried playing with temps and layer height, and it seems to work slightly better on higher temps but still having issues. I also tried doing a cold pull and cleaning the bed with dish soap. Any ideas what is the culprit would be appreciated! Thank you!
RE: Problems with first layer (retractions, overextrusion?)
I tried something maybe I should've done before and just tried the other side of the steel sheet. Adhesion is much better. Still some stringing going on, not sure if it's a calibration issue or what.
RE: Problems with first layer (retractions, overextrusion?)
Adhesion issues on a PEI sheet is almost always finger prints and oils left behind when you handle the sheet. Soap and hot water is the best cleaning method. Take the sheet to the sink, use Dawn or similar plain dishsoap, plain paper towels to scrub and dry with, and never touch the print surface with your fingers. Handle only by the edges.
And, before you say you've cleaned the sheet with alcohol, acetone, etc.; if you actually did this, then why is the plastic still not sticking? It's because alcohol dissolves the oils and simply dilutes it and spreads it into a microthin layer. It is hard to beat the cleaning efficiency of gallons of soapy hot water and a running water rinse compared to a dram of alcohol.
RE: Problems with first layer (retractions, overextrusion?)
It might've just been poor cleanliness of the bed.
However! Tried printing some TPU today for which I decreased the tension on the extruder gears. After going back to PLA now I tightened it a bit less than it was before (realized it was too tight), and now the prints look better. Could that have been an aggravating factor?