[Closed] Hotend jam consistently happening  

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elizabeth.worrall
(@elizabeth-worrall)
New Member

I've been printing PLA for a while now (gone through 3 kg of it) since I bought it late last year. However, I keep getting jams in the hotend and have to keep doing cold pulls to get it out. I push the PTFE tube as far down as it can go and pull the black ring up as much as I can, but I've had to change over the tubing three times and not get a completed print. I was getting blockages with a PLA filament I was using for the first 3 spools but they weren't that bad, but then I changed over to a different PLA filament and I can't get a complete print with it. It will print fine for a few hours then get blocked. I've tried increasing the temperature a little (to 215) but it still blocked. I even had a go at putting a bit of cardboard under the black tube to stop it from moving. Any suggestions on where I'm going wrong?

This topic was modified 10 months ago 2 times by elizabeth.worrall
Posted : 10/01/2020 12:10 am
covertpluto
(@covertpluto)
Trusted Member

Hi, your hotend fan might not be working normally. The filament will stick to the heartbreak if the fan doesn’t cool. Try running self test and clean any dust in the heatsink.

This post was modified 5 months ago by covertpluto
Posted : 26/05/2020 12:33 pm
Neophyl
(@neophyl)
Noble Member

One thing missing from a Mk3 standard build that really should be there is the locking ring that goes underneath the black ring and keeps it pulled up.  If you buy a hotend from e3d they include them but for some reason Prusa dont use that part.  I normally print off several and then fit them as standard. Something like this https://www.thingiverse.com/thing:618001  

With lots of retractions the ptfe can work its way up slowly and then you get a gap and then you get a jam.  With the little lock it stops the ptfe from working loose.  I wont say its a cure all but I have never had that sort of jam om my Mk3 (then again I have a silicone sock too which makes a big difference).  I wouldn't say I'm a heavy user but I've gone through well over 30 1kg spools since I bought my Mk3.

Posted : 26/05/2020 12:51 pm
covertpluto
(@covertpluto)
Trusted Member

@neophyl

Hi, looks like you have got the Bowden version of it. Should be just fine if you insert the tube in fully, then use your fingernails to gently pull the black collet away from the heatsink.

Posted : 27/05/2020 6:58 am
Neophyl
(@neophyl)
Noble Member

That was just the first example I found yesterday while searching from the work computer as an example, the one I printed is almost identical to the E3d supplied version.  If you go to the E3d website and look at their hotend kits you will see that they include and instruct the use of the spacer to ensure that the collar is always kept raised.  As E3d makes the hot ends for Prusa and except for a minor prusa specific change to the heatbreak for MMU use the rest is a stock V6 setup.  If the manufacturer fits them as part of their standard kit then there is probably a good reason for that.

btw E3D refer to the black plastic collar as a Collet and the little plastic locking ring is a Collet Clip.   You can see all the parts for a standard V6 kit here https://e3d-online.dozuki.com/Wiki/V6_Parts

Posted : 27/05/2020 7:26 am
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