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Extrusion jamming what should I check  

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Bob
 Bob
(@bob-2)
Reputable Member
Extrusion jamming what should I check

My Prusa Mini has been offline for about a year now due to extrusion problems.  When I first go the printer it worked beautifully and gave me many successful prints, some that took over 24 hours.  Then is started have feed problems were it started jamming.  I tried changing filament including Prusa branded filament and others that have been successful in my Prusa i3 and Ender 3.  I tried replacing the tubing in the hot end with Prusa replacement as well as Capricorn.  I tried replacing the nozzle using both Prusa and 3rd party.  My next step is to replace the heat brake, I'd read that some believe the OEM heat brake is too thick allowing heat creep to cause problems. 

Before I go so deeply into this I want one more last opinion.  I did a search and I don't see many complaints about jamming over the last year, it seems the most recent was 9 months ago.  So, before I do major surgery on my mini, has someone come up with a solution to the jamming the minis have been prone to?

 

Thanks

-Bob

Prusa I3 Mk2 kit upgraded to Mk2.5s, Ender3 with many mods, Prusa Mini kit with Bondtech heat break, Prusa I3 Mk3s+ kit

Posted : 30/12/2021 1:13 am
KTH
 KTH
(@kth)
Trusted Member
RE: Extrusion jamming what should I check

is it jamming at the nozzle or extruder?

Posted : 30/12/2021 3:39 pm
Bob
 Bob
(@bob-2)
Reputable Member
Topic starter answered:
RE: Extrusion jamming what should I check

I'm assuming it's at the hot end, I can get a good first layer or 2 then it starts clicking and under extruding.  I've been following various recommendations in the forum and got frustrated and gave up.  I purchased a Bondtech heat break hoping that's the solution.  Since it's been months since I set this aside I'd hoped someone had found a silver bullet to this problem.  Since I saw a new post today from someone with a similar issue I'm guessing one hasn't been found.

-Bob

Prusa I3 Mk2 kit upgraded to Mk2.5s, Ender3 with many mods, Prusa Mini kit with Bondtech heat break, Prusa I3 Mk3s+ kit

Posted : 30/12/2021 3:49 pm
TeachingTheDetails
(@teachingthedetails)
Eminent Member
RE:

Not sure, if you've the exact same problem, but my Mini used to regularly jam. I'd do a cold pull, clean the nozzle with a needle, take apart the extruder and clean the gear from debris, etc.. That would make it print again for a while, before eventually jamming again.

In the end, it was the idler that was too tight, grinding the filament, leading to underextrusion or full on jams. 

The tutorial with aligning the idler screw flat to the surface of the extruder never made sense to me and allowed too much variance. So I ended up using the following method to get the correct idler tension:

- Unload filament

- Remove the bowden tube from the extruder (so that the filament will exit the extruder without going to the hotend)

- loosen the idler screw completely

- Set nozzle temp to 200° (so the extruder will allow extrusion)

- Manually feed filament into the extruder

- On the Mini, go to settings-> Move axis -> Move E ->turn wheel to extrude

- slowly tighten the idler screw until the extruder gear starts extruding the filament

Leave the idler screw at this tension, where it's just enough tension to feed the filament.

Now all that's left is to reattach the bowden tube and start printing.

Ever since adjusting the idler tension this way, I've not had a single jam. 

hw: PRUSA MINI+, FW 4.3.3 & Cr-10s w/ BLTouch, Ezboard, Hemerasw: PrusaSlicer 2.4, Windows 11

Posted : 30/12/2021 4:12 pm
Bob
 Bob
(@bob-2)
Reputable Member
Topic starter answered:
RE: Extrusion jamming what should I check

simple enough process, I'll give it a try.

thanks

-Bob

Prusa I3 Mk2 kit upgraded to Mk2.5s, Ender3 with many mods, Prusa Mini kit with Bondtech heat break, Prusa I3 Mk3s+ kit

Posted : 30/12/2021 4:58 pm
Bob
 Bob
(@bob-2)
Reputable Member
Topic starter answered:
RE: Extrusion jamming what should I check

I implemented your solution and so far so good, I have a Hubs Marvin printing now, we'll see how it goes.  One issue I had though was I couldn't get the filament to not extrude, even with the bolt completely removed it would still extrude, so I basically just set it to minimum pressure.

-Bob

Prusa I3 Mk2 kit upgraded to Mk2.5s, Ender3 with many mods, Prusa Mini kit with Bondtech heat break, Prusa I3 Mk3s+ kit

Posted : 31/12/2021 7:02 pm
Bob
 Bob
(@bob-2)
Reputable Member
Topic starter answered:
RE: Extrusion jamming what should I check

It's not looking hopeful.  I'm printing my first "real" print and I'm suffering under extrusion.  It started clicking on the first layer which could be a z-offset issue, but I have a lot of practice on z-offset so I'm kinda' doubting it.  Right now it's on the first layer which is NOT clicking but still under extruding. 

I'm running the current firmware, 4.3.4.

It's such a sweet machine when it's printing well and such a PIA when it isn't.

-Bob

Prusa I3 Mk2 kit upgraded to Mk2.5s, Ender3 with many mods, Prusa Mini kit with Bondtech heat break, Prusa I3 Mk3s+ kit

Posted : 02/01/2022 9:05 pm
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