Check your bowden tube!
I've had my Mini for 18 months and love it. Recently the print quality hasn't been great. I was getting Z banding and under-extrusion in areas that had lots of quick switching between printing and retracting. I replaced the nozzle and the hotend PTFE tube, tightened the idler screw and checked belt tension. Nothing helped. I noticed a while ago that the filament would move up and down significantly inside the bowden tube when retracting but didn't give it any thought. Then it hit me. Replacing the bowden tube fixed all my print issues.
I couldn't bring myself to spend $16 on a $2 part from Prusa so I ordered the PTFE tube below from amazon. The cut end of the filament requires a little extra effort to push through but so far this tube seems to work. The only thing I don't like is that it's not as translucent as the original part. I can see dark colored filament through it but not light colored.
Tools
I've had my Mini for 18 months and love it. Recently the print quality hasn't been great. I was getting Z banding and under-extrusion in areas that had lots of quick switching between printing and retracting. I replaced the nozzle and the hotend PTFE tube, tightened the idler screw and checked belt tension. Nothing helped. I noticed a while ago that the filament would move up and down significantly inside the bowden tube when retracting but didn't give it any thought. Then it hit me. Replacing the bowden tube fixed all my print issues.
I couldn't bring myself to spend $16 on a $2 part from Prusa so I ordered the PTFE tube below from amazon. The cut end of the filament requires a little extra effort to push through but so far this tube seems to work. The only thing I don't like is that it's not as translucent as the original part. I can see dark colored filament through it but not light colored.
And there are plenty of jigs to cut you own.
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Chuck H
3D Printer Review Blog