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Bad printing - extruder issue?  

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YigalB
(@yigalb-2)
Eminent Member
Bad printing - extruder issue?

My 3+ years Prusa Mini was working perfectly until lately. 

First layer calibration works well, the printing seems to be good, then it looks like purging is stopping for while - take a look at the pictures.

I cleaned the printing head, re-calibrated and it happened again.

I start suspecting the extruder: firstly because Prusa support guided me to tighten the screw, and also because the problem is bigger with certain filaments.

1- what do you think? Any ides?

2- How to calibrate the screw? The manual states it has to be flush with the plastic, but nothing is said about fine tuning.

3- What is the effect over tightening? less purge? 

4- what is the effect of loose tightening/no tightening at all? I am not sure I understand the role of the screw.

5- Should I replace the extruder? Any recommendation for a non-Prusa better extruder? (perhaps with built in sensor?)

 

Thank you

 

Posted : 14/05/2024 4:42 am
fuchsr
(@fuchsr)
Famed Member
RE: Bad printing - extruder issue?

Go with the Bondtech IFS extruder or the aTrianglelab clone. The only update I wholeheartedly recommend for the Mini. I have it on my two Minis, and never had to change the tension of the extruder screw again, which was a constant with the stock extruder.

Posted : 14/05/2024 11:29 am
YigalB
(@yigalb-2)
Eminent Member
Topic starter answered:
RE: Bad printing - extruder issue?

 

Posted by: @fuchsr

Go with the Bondtech IFS extruder or the aTrianglelab clone. The only update I wholeheartedly recommend for the Mini. I have it on my two Minis, and never had to change the tension of the extruder screw again, which was a constant with the stock extruder.

Sounds good, yet I wonder about the "again" - so you had to tune the tension once? I am concerned about the tuning. 

Posted : 15/05/2024 4:51 am
fuchsr
(@fuchsr)
Famed Member
RE:

"Tune" is giving it too much credit. I just screwed the screw in and backed it off a couple of turns or so as per the Bondtech instructions. It's been years but I know I didn't go through any tuning process. 

This post was modified 1 month ago by fuchsr
Posted : 15/05/2024 10:43 am
YigalB liked
YigalB
(@yigalb-2)
Eminent Member
Topic starter answered:
RE: Bad printing - extruder issue?

The problem was solved by tightening the idler screw. 

Although the online database (  https://help.prusa3d.com/article/idler-screw-tension_177367  ) states to align the screw with the surface, I had to tighten it more. I guess it needs more pressure on the filament (is it so?).

The  user guide doesn't state how to calibrate it, or what are the tradeoffs of the different tightening options. 

Posted : 30/05/2024 7:15 am
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