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Filament Jam Issues (heatCreep?)  

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Crab
 Crab
(@crab)
Reputable Member
Filament Jam Issues (heatCreep?)

After about 1.5 years on my MK3S+, I'm just now having issues that I'll try to describe below. Basically I'm getting jams by filament lodging in the PTFE tube.. 

I've been printing a lot of PLA lately at about 210 and I can unload it fine.. When it comes out, I pull on the filament a bit to help it, but it seems to have a nice molten end, which I snip for future reinsertion. Many times now when I go to put a new color of PLA in, there is a block in the PTFE tube which had about a 3-5mm piece of filament in there.. No way I can see how it got there because the filament usually comes out okay.. But I did have a few time in a print with color change that the unload sequence did not release the filament and I really had to pull it hard.. but at that time it did reload a new color.. This is also happening a few times on color changes.. the hard unload.. and it had never happened before last week.. .

Mostly when I removed the PLA filament, it seemed to come out fine with a molten end. Had this about 4 days ago and no way I could get the block out and I ended up totally disassembling the hot end and replacing the PTFE tube. I had no experience at that repair, but seemed to go okay.. I recalibrated, new Z offset and things are fine.. But now I find that issue is coming back.. I can get around it a bit by unloading the new filament when it gets blocked .. then cutting a new end.. and really forcing it down into the tube with hand pressure help.. Sometimes I need to do this a few times.. 

Something is wrong.. and I have no real knowledge of hot-end issues. 

Any help and suggestions appreciated, even if it requires changing the hot end.. 

 

Posted : 12/12/2023 2:20 am
zukpr
(@zukpr)
Eminent Member
RE: Filament Jam Issues (heatCreep?)

 I had a TPU jam recently that required me to stick the needle up the hot end to break it loose. Then I did a cold pull to clean out the nozzle more fully. Now it is printing like a charm again. You might try that.  You can find directions to do a cold pull in the Prusa help documentation. 

Posted : 12/12/2023 5:38 am
RandyM9
(@randym9)
Honorable Member
RE:

Check the idler pulley. It will get jammed with filament dust over time and need more force to spin. 

Undo the tension screw and pop the idler pulley door open. If the gear doesn’t turn freely by hand, remove the hinge screw holding the door and take it off. Push the axle rod out of the housing and remove the pulley (it may go easier one way and not the other so if it seems like it’s binding, push in the other direction) then push the two needle bearings out of the pulley with the Allen key. Check the online manual for pics and better instructions.

Soak all the parts in IPA for a while, moving the parts around a few times, them remove everything, dry thoroughly and put a drop of light machine oil on the bearings. After letting the oil seep in, wipe off the excess and reinstall everything.

This may not be the issue, but it’s worth checking.

Cheers

This post was modified 11 months ago by RandyM9
Posted : 12/12/2023 9:44 pm
Crab
 Crab
(@crab)
Reputable Member
Topic starter answered:
RE: Filament Jam Issues (heatCreep?)

Thanks.. did a cold pull and got a bit of crud.. but I had the tension on the filament too loose. Had loosened it for TPU and didn’t tighten again and so it was stripping filament.. Used @RandyM9 suggestion and found lots of dust in the gears.. Cleaned that out really well and seems to be good now.. Thanks for suggestions to both. 

 

Posted : 13/12/2023 2:02 am
zukpr
(@zukpr)
Eminent Member
RE: Filament Jam Issues (heatCreep?)

Sweet. Glad it is working again. 

Posted : 13/12/2023 3:28 am
RandyM9
(@randym9)
Honorable Member
RE: Filament Jam Issues (heatCreep?)

Glad you got it sorted.

Cheers

Posted : 13/12/2023 4:28 am
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