Filament jams happens quite often, when using retraction - what to do?
 

Filament jams happens quite often, when using retraction - what to do?  

  RSS
Rasmus
(@rasmus)
New Member

I have the Original MK3S, and lately I have had problems with filament jams.

When I print, suddenly it starts to "click" from the extruder motor. When I try to unload the filament I can't and the filament typically breaks just above the PTFE tube, as the filament have been worn down due to grinding. To fix it I usually end up removing one side of the extruder gears, and with a small plier try to grab what is left of the filament. At the same time I will use a small needle and insert into the nozzle to loosen up what ever is stuck. When the filament is removed I can usually reinsert the filament at print again.

I noticed it mostly happens on prints, where there is a lot of retraction due to lots of small areas to print. Today it happened, when I printed the "Cute Mini Octopus".

I think it might be caused because the filament gets soften by the extruder motor getting very hot - is that likely?

 

My printer is in a IKEA LACK enclosure, and the ambient temperature is around 28c in the enclosure. Outside it is aprox. 23c.

The printer is a MK3 that was upgraded to MK3s. When the jams started happening quite often, I replaced the PTFE tube, but that didn't solve the problem. I print with Prusament PLA Galaxy Black at the moment, but I have seen the same problem with another brand and with PETG as well.

This topic was modified 1 year ago by Rasmus
Posted : 08/08/2019 3:38 pm
thomasa88 liked
AlmostSheldonPK
(@almostsheldonpk)
Active Member

How high is your retraction settings?

Posted : 08/08/2019 9:41 pm
Rasmus
(@rasmus)
New Member

It is all standard in PrusaSlicer. Printing 0.20 quality profile with Prusament PLA selected.

This post was modified 1 year ago 2 times by Rasmus
Posted : 08/08/2019 10:43 pm
Tim
(@tim-m30)
Illustrious Member

Keep the enclosure doors wide open; and if your unloaded filament has a stub that measures 2.2 mm , you might considered swapping the heat break for a stock E3D variety.

It is always wise to get more than one opinion......
Posted : 08/08/2019 11:56 pm
kai liked
Nigel
(@nigel)
Honorable Member

That's what I did. I fitted the stock E3DV6 heat break.  No clogs since.

Nigel
Life is keeping interested and excited by knowledge and new things....
Posted : 12/08/2019 3:01 am
kai liked
chadelp
(@chadelp)
Active Member
Posted by: Nigel

That's what I did. I fitted the stock E3DV6 heat break.  No clogs since.

Why didn't the printer ship with the stock 2.0mm heat break instead of the 2.2mm? Should I go ahead and buy the stock e3d now?

Posted : 14/08/2019 1:09 pm
Tim
(@tim-m30)
Illustrious Member

Prusa has E3D modify the stock V6 heat break by drillingout the bore to 2.2 mm from the PTFE top end down to about the neck transition zome. The choice of depth was I think random, and doesn't adequately consider where filament actually begins melting. So the step is slightly higher than a typical melt point. Retractions and the hydraulic nature of the filament melt causes the melt to pump out of the melt zone up into the cold zone, where it hardens and becomes a 2.2 mm plug. Hence a jam occurs.

The heat break needs to be 2.2 mm for people using an MMU.  When unloaded, filament has a small string attached. When reloaded automatically by the MMU, this string folds back on the filament and adds to the diameter required to pass down the heat break. 1.75 mm + string > 2.0 mm will jam. Most strings are less than .5 mm, so 2.2 mm was enough.  At the step, the filament is normally warm enough the thread will now pass into the 2.0 mm bore. It's chance it works, or doesn't work. Some people can't get their MMU's to work well, either. 

 

It is always wise to get more than one opinion......
Posted : 14/08/2019 8:14 pm
kai
 kai
(@kai)
New Member

Hello all.

I have my MK3S for a couple of weeks now, extruder clicking from day one. Just replaced the Prusa heatbreak for a regular one, 12,90€. Works like a charm now. 🙂

Kai

Posted : 16/08/2019 4:34 pm
thomasa88
(@thomasa88)
Active Member

I have the exact same problem on my MK3S. Is it correct to assume that if I change to a shorter retraction distance, it will take a higher number of retractions before a clog forms?

Feels harsh having to buy a new heatbreak for a completely new printer 😞.

This post was modified 1 year ago by thomasa88
Posted : 01/09/2019 6:16 am
Tim
(@tim-m30)
Illustrious Member

Immediately after a jam, do a normal filament unload.  Measure the filament stub.

This 2.2 mm stub is caused by the heat break and retraction pumping the melt upwards.  It won't fit into the lower 2.0 mm section of the heat break. If you look closely, you can see the 2.0 mm section form just at the tip. 

Reducing retraction won't help, much.  Adjusting the heat break to be farther into the heater block - 1/4 to 1/2 turn - might help.

 

This post was modified 1 year ago by Tim
It is always wise to get more than one opinion......
Posted : 01/09/2019 9:34 am
thomasa88 liked
paul.c63
(@paul-c63)
Active Member

I'm working with the mk3s and it is having the same issues. It printed fine for a month or so until it started to have extrusion issues. I switched the heat break out for a regular e3dv6 heat break and just fired it up last night to find that it still doesn't work. I printed a rather large benchy and it was near flawless. I put it through a torture test by printing a really detailed chess set https://www.thingiverse.com/thing:3423559 that it had always failed on before with the Prusa heat break. Now with the new e3d v6 heat break it again failed halfway the print (24 hours total 12 hours in).

Any ideas? I've only been using pla, the pla could be wet with me being in a very humid climate. It also could be from a lack of oiling because it's sat idle for a long time and I haven't used the suggested oil instead I've used hair clipper oil.

 

Posted : 02/09/2019 2:33 pm
markus.i2
(@markus-i2)
Trusted Member

When that happened to me, I found that leaving the enclosure door open helped. Which is why I'm working (again, on and off, for the last year, so don't expect any miracles soon) on a temperature controlled fan for the enclosure.

As for cleaning out the filament - in most cases (for me) it works if I heat up the nozzle (maybe at the upper limit of what's recommended for that filament) and then push the offender through from the top with another piece of filament. Maybe loosen the extruder gear before. Less effort than disassmebling the extruder 😉 

Posted : 03/09/2019 5:51 pm
thomasa88
(@thomasa88)
Active Member

I just ordered a V6 heatbreak. Hope it helps 😅.

 

@paul-c63 Did you use to get the 2.2 mm filament end as tim-m30 described?

Posted : 04/09/2019 6:34 pm
paul.c63
(@paul-c63)
Active Member

I did use to get them. I don't with the heat break switched, but still something is jamming.

Posted : 07/09/2019 9:22 pm
andreas.t4
(@andreas-t4)
New Member

Yes, I'm also getting these filament jams quite often, especially when printing with slow with prusament.
I tried changing to the mk2s heat break (which is supposedly the original 2.0mm heat break), but that hasn't helped.

Posted : 08/09/2019 9:44 am
Tim
(@tim-m30)
Illustrious Member

If - after a jam - you see 2.2 mm on an unloaded tip, there's good confidence the heat break is the culprit.  If you have filament piling up above the PTFE, then it is probably the motor/enclosure jam - and adding ventilation is the best fix.  

There are probably 20 other problems that I know of that cause jams: filament filled with pretty flecks; glow in the dark; metal filled; wood filled; and then mechanical issues with a spool hold not rolling; filament on rolls behind the printer snagging on something; printing too low a temp; printing after printing a higher temp material and not cleaning the nozzle properly; not watching the filament for foreign particulates that clog and jam...

It is always wise to get more than one opinion......
Posted : 08/09/2019 1:29 pm
andreas.t4
(@andreas-t4)
New Member
Posted by: Tim

If - after a jam - you see 2.2 mm on an unloaded tip, there's good confidence the heat break is the culprit.  If you have filament piling up above the PTFE, then it is probably the motor/enclosure jam - and adding ventilation is the best fix.  

There are probably 20 other problems that I know of that cause jams: filament filled with pretty flecks; glow in the dark; metal filled; wood filled; and then mechanical issues with a spool hold not rolling; filament on rolls behind the printer snagging on something; printing too low a temp; printing after printing a higher temp material and not cleaning the nozzle properly; not watching the filament for foreign particulates that clog and jam...

I got a jam again yesterday when printing a model with a lot of retraction, and looking at the filament after pulling it out it sure looked like the picture above, with the lowest bit being slightly wider.

Posted : 09/09/2019 4:35 pm
cameron.w9
(@cameron-w9)
New Member

I had my heater block get totally covered in PLA with a bad print I didn't catch in time so I recently switched my block with a new E3d block and a new E3D V6 heat break and now I'm having this problem. But I didn't have any heat transverse paste around the night I did it so I didn't apply any to the heat break. Do you suppose that would be enough to cause this problem too. I get the clicking and the jam.

If I start a PETG print after about 30 minutes it jams. PLA can print for a few hours then sometimes it jams and other times it will finish.  Just wondering if I should pull it apart again and apply some thermal transfer paste?

Posted : 10/09/2019 4:09 pm
tom.h20
(@tom-h20)
New Member

@cameron-w9

Sorry for necroing this thread, I hope you have solved the problem. Thermal paste is quite important IMO, without it, there could be insufficient hear transfer from the heartbreak to the heat sink. 

This post was modified 8 months ago by tom.h20
Posted : 25/02/2020 9:56 pm
Share:

Please Login or Register