Weirdest first layer problem I have ever had
Genuine unmodified mk3s
Firmware 3.10.1
Prusa Slicer 2.4.2
Nozzle is good
Re-done first layer calibration successfully, nozzle height appears to be perfect
This is a known good print I have done several times before (all prints affected)
I have cleaned and tested the extruder, by running the extruder manually from settings menu, and it is near impossible to stop the filament by grabbing it while running an extrusion, so the grab from the extruder gear is perfect
This fault just started suddenly when everything was previously working fine.
On the first layer, it appears that half way across putting a line down, it starts retracting the filament tiny amounts and makes itself lose grip, then on the way back down the line it starts extruding properly again and it starts grabbing the filament properly, then at around the same spot it seems like the extruder starts retracting again as it loses grip. It does the same thing over and over again at the same point across the bed.
Anyone seem something this crazy before? I have no idea how to solve this one
Thanks for any help
RE: Weirdest first layer problem I have ever had
Anything stuck under the steel sheet? I had some weird extrusion patterns which were caused by a tiny speck of filament stuck to the heated bed.
RE: Weirdest first layer problem I have ever had
I am certain the steel sheet is flat to the bed.
It probably doesn't show well in my photo, but the outline that the printer draws first, it perfectly formed all the way around the object
If you move the part to another part of the bed, or rotatate it, does the problem move with the part or stay in the same area of the print sheet?
Does the other side of the print-sheet show the same problem?
Cheerio,
RE: Weirdest first layer problem I have ever had
I re-sliced the same print rotated 90 degrees and the problem is still in the same place.
If the problem remains in the same place *on the print sheet* then there are two main possibilities:
a contamination problem - a thorough cleaning of the sheet might be enough...
Or a bent/dented sheet - lie it flat and shine a light at it edge on - is there a shadow or highlight in that spot?
Cheerio,
RE: Weirdest first layer problem I have ever had
If I pull on the filament while it is printing, it is definitely retracting when it gets to that point.
The only reasonable explaination I can think of is a bad connection to the extruder motor when it hits that spot.
I am pulling apart the extruder now to check the wiring. I forgot how much of a pain the original extruders are to work on
RE: Weirdest first layer problem I have ever had
I removed the extruder motor, untwisted the wires and snapped the blue wire. So there we go, if anyone else sees this weird problem, it is an intermittent connection to the extruder motor
RE: Weirdest first layer problem I have ever had
That certainly seems like a good explanation why it happened at that spot.