Original Prusa filament jamming issues

Hello,

after purchasing Prusament and trying to print with Flex3Drive extruder I started to have jamming/clogging issues. Since I was using a genuine e3d V6 except the chinese heatbreak (which broke when hot tightening) , we (me and Flex3Drive creator) thought that it might be caused due to bad finish of the inner bore of heatbreak. Since the chinese e3d's have 0 quality control I tried polishing the inner bore aswell as trying other heatbreaks. The results were mixed but from 3 different heatbreaks we learned that all were jamming with the Prusa filament. All jammed in different times, one could print for half hour, other for 3 hours and the last for 1 hour without clogging. After using the cold pull/ atomic mehtod I could print just fine for another 30 minutes, 2 hours or so ... then a jam one again.

What we tried is to print without retraction, changing the temperature from 210 (Prusa suggests this temp for their PLA) and lastly changing the filament. From these actions only the last one worked. When switching to cheap Gembird filament i was able to print 4 hour long print with hunderds of retractions just fine, while still using the same heatbreak that was getting jammed/clogged.

Now the problem cant be the extruded since I played with the settings of vref, changed motors to no avail. I am 99% sure that the clogg must be coming from the heatbreak or the nozzle since after the clogged appeared I tried pushing the filament (with tension arm released) by hand with brutal force but nothing came out at all. The main difference between the filaments is that the surface finish on the cheap ones is shiny and smooth (1,72 - 73 diamater) and the prusa filament is rough to touch and matte, indicating some degree of abrasion (1.75 diameter).

I ordered a genuine heatbreak from e3D to try to assemble a full genuine e3d v6 this time to see if it still causes problems. In the mean time, any suggestions on what might be wrong ? This jamming started only with Prusa filament.

Hi Welo78,

Have you tried dis-assembling the extruder and looking how the filament jammed?
On the Prusa MK3 we changed the extruder fan for a bigger, higher CFM one at 24VDC (we wired it directly to 24VDC and it is always fully on). The issue we encountered is that the filament would not be cooled fast enough and would still be soft inside the pre-extruder.
As you go faster in print and higher temp on the nozzle the filament would jam inside. No issues since, of course it all depends on what you print and how you print.
Nozzle quality is also imporant to consider...

Well just our thoughts on this...

When it jams, does the extruder chew a divot into the filament? If so, you may need to crank up the pinch roller pressure so the drive gear teeth bite more deeply into the filament.

Keep retraction length as short as possible, too.

Edited 1 time(s). Last edit at 10/31/2018 12:14PM by the_digital_dentist.

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