Bad print quality
I just finished upgrading my MK3S+ to MK3.9 the other day, but I encounter problems with the print quality. There is a lot of stringing and the layers do not seem to be regular.
I have same results with all filaments I tried (Prusament, eSun, Spectrum). I increased the value of retraction (as far as 2mm), but no improvement.
The only thing that seemed to help has been reducing the nozzle temperature to about 180 degrees, but even then it was far from perfect and I started getting nozzle cleaning issues.
I have no clue on what I could try next.
RE: Bad print quality
I have the same problem and nothing work, i print with a MK3S+ the same object and i have no problem but with the MK3.9 it's a disaster
RE:
After building my MK3.9 kit, I had a similar problem with really bad stringing when I used the default temps for PLA and PETG in PrusaSlicer. If I lowered the temps from PLA from 215 to 180, my stringing went away. I contacted Prusa support and they determined that my hotend thermistor needed to be replaced. My original hotend thermistor was all black. The new one they sent me has half blue wires and half black wires (see the Prusa eshop for a picture). There is a thread on the MK4 forum on this issue. This replacement part fixed my problem and now my prints are perfect. Hope that helps.
RE: Bad print quality
After building my MK3.9 kit, I had a similar problem with really bad stringing when I used the default temps for PLA and PETG in PrusaSlicer. If I lowered the temps from PLA from 215 to 180, my stringing went away. I contacted Prusa support and they determined that my hotend thermistor needed to be replaced. My original hotend thermistor was all black. The new one they sent me has half blue wires and half black wires (see the Prusa eshop for a picture). There is a thread on the MK4 forum on this issue. This replacement part fixed my problem and now my prints are perfect. Hope that helps.
Concur. I had a similar problem. This needs a store chat report for assistance.
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Chuck H
3D Printer Review Blog