Printing a simple piece, about 70 mm high, in black PLA. a little over half was up, a horizontal seam appeared. See photo. Piece was oriented like that in printer, left side facing back of printer. The seam protrusion is worse near the back, almost disappears about 3/4 way toward front.
Speculating: like filament was overheated briefly.
Any ideas??
Thanks
Here’s a checklist for starters:
That is indeed a mysterious mid-print flaw. I agree with your theory that some kind of mid-print interference in filament flow caused this issue. Overheating doesn’t seem to make sense though, mainly because I would not expect such a hardware failure to be momentary, as the output clearly indicates. It’s not impossible, but it seems improbable on such a smooth surface. If it were a loose wire on the thermistor as an example, I would expect printer vibration to cause such a defect to appear randomly throughout the print. You mentioned it only happened at one level and trailed off.
My initial reaction might be that there was a snag in the spool during winding at the factory, causing a portion of the filament to get wedged in the side. This could have led to a momentary drag with subsequent flooding forward although admittedly I can’t envision how that could happen either. I can’t discern from the photo, but if you could provide a closeup and look for evidence of under-extrusion before the over-extrusion, that might lend support to this alternative theory.
Have you been able to repeat this flaw?
I first suspected something mechanical that stalled the head, but it would have been a long event (that seam wraps around to the other side).
Looking more closely, I think what may have happened it the part lifted (partially) from the bed at that point. It seemed firmly attached at end of job, so I didn’t initially suspect lifting.
top photo is bottom surface.
bottom photo is front edge. you can see the change in surface angle.
The moire pattern is a webpage artifact.
So CanDo’s comment #2 is likely the case.
I’ve had a lot of bottom surface curling recently.
Thanks.
see my comments below
If the bottom of the print is on the left of the last photo, it does look like the left side is narrower at the fault layer, like the print detached from the plate and “rolled up and to the right” so there’s some horizontal displacement.
Simple solution for PLA: wash the plate gently with warm water and dishwashing liquid (don’t scour it) and apply some glue.
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