MK3S stops extruding mid print (filament grinding)  

RE: MK3S stops extruding mid print (filament grinding)

So I'm very confused zen-k above said he switched to the standard e3D v6 1.75mm heatbreak... What am I missing?

zen-k

I would suggest you buy a standard e3D v6 1.75mm heatbreak. You can buy one on amazon for around $16. Since I’ve switched mine out, I haven’t had a clogging issue.

RE: MK3S stops extruding mid print (filament grinding)

Pictures are worth too many words.

Prusa has E3D add a 2.2 mm bore to the heat breaks they buy, they are otherwise the same.

Prusa's heat break is a modified E3D-V6; but has 2.2 mm to 2.0 mm step in transition zone:

E3D-V6's heat break; no step, constant full length 2.0 mm bore:

RE: MK3S stops extruding mid print (filament grinding)

Thanks so based on that it would be beneficial to switch to the standard version, the video I watched indicated that it was that step that was causing the clogging issues. Hopefully that will fix the issues I'm having. Thanks for the help gents!

RE: MK3S stops extruding mid print (filament grinding)

Here's evidence the Prusa step is the cause of the jamming:

Filament hammering (retraction/deretraction) pushes melt out of the hot zone 2.0mm cavity into the 2.2 mm cold zone, where it builds up and solidifies, and no longer fits into the melt zone. Thus it jams.

Here is another set of examples from my printer:

RE: MK3S stops extruding mid print (filament grinding)

And they kept telling me to try a cold pull but with the way it solidified at the end of the tube there was no way to pull it thru. Thanks again that makes me feel better about the standard version of the heat break I just ordered. Now if I can figure out how to get the old one out without breaking it off inside the hot end.

RE: MK3S stops extruding mid print (filament grinding)

I think you are on the right track. You should be able to check the idler gear and bearings without completely disassembling the extruder. You should also be able to adjust the Bondtech filament gear alignment as well (Step 30, page 28 of your assembly instructions).

Best of luck.

RE: MK3S stops extruding mid print (filament grinding)

Posted by: rickscncdesigns

And they kept telling me to try a cold pull but with the way it solidified at the end of the tube there was no way to pull it thru. Thanks again that makes me feel better about the standard version of the heat break I just ordered. Now if I can figure out how to get the old one out without breaking it off inside the hot end.

Pretty easy to do ... you can usually heat the nozzle to 285c, and that warms the transition zone enough the filament stub will melt and flow through the nozzle (blocking the cooling fan air flow can help expedite this extra heating at the heat break).  Once you've pushed a cm or so down, the filament will unload normally.

RE: MK3S stops extruding mid print (filament grinding)

Posted by: zen.k

hi but issue is im not getting clogging just filament grinding and breaking tho i already ordered a new heatbreak

Zen clicking is caused by clogging and jams.  If the filament flows normally, there is no back pressure and the extruder doesn't click.  Saying you don't have clogging while the extruder clicks is like saying you don't have a flat tire yet air pressure in the tire is zero.

RE: MK3S stops extruding mid print (filament grinding)

Got the new heat break installed this morning and so far two perfect prints and no issues. Thanks tim-m30 your input was very helpful!

Rick

RE: MK3S stops extruding mid print (filament grinding)

The E3D V6 hotend is air cooled and rated to operate at up to 40C ambient temps. If your enclosure temp is at or above that temperature, there's a good chance materials with low melting point such as PLA can soften prematurely. That's why people with these problems often only have the clicks or jams when printing PLA. Filaments with higher melting temps do fine. Simply opening the enclosure up to ensure proper airflow is a simple test as part of a process of elimination.

Have you loosened or adjusted the extruder tension screw(s)? That's another common cause of these symptoms. It can all be cumulative as well, so make incremental changes and test.

RE: MK3S stops extruding mid print (filament grinding)

Heh. Just realized I responded to an early post in a 7 page thread. Nevermind!

RE: MK3S stops extruding mid print (filament grinding)

Posted by: bobstro

Heh. Just realized I responded to an early post in a 7 page thread. Nevermind!

I've done that - hitting "LAST POST" doesn't really get you to the last post. And had 4 posts in a row answering the same query ... I really despise this new forum.

RE: MK3S stops extruding mid print (filament grinding)

I'm brand new to 3D printing, and just got a MK3S.  I was able to print 3-4 small models (PLA), then the dreaded clog happened and it hasn't worked since.  I took out the original PTFE tube and it had melted into an odd shape.  I cleaned out the nozzle, inserted a spare tube and verified with the acupuncture needle that all was clear, but it still wont print.

This sounds like the same problem.  Is everyone going to have to buy this new part now??

RE: MK3S stops extruding mid print (filament grinding)

Prusa emailed me back today and wanted me to retry the firmware fix but I told them I had already replaced the heat break and that it seemed to fix the issue. I doubt seriously that the firmware will do anything because I don't think it's the heat from the extruder motor that is causing the issue. So to answer your question yes I think the quickest fix is to order the original not the Prusa modified heat break. :/

RE: MK3S stops extruding mid print (filament grinding)

Update:  I went back in time and read an earlier post talking about the gear pressure being uneven and grinding unevenly.  My drive gear is so far over the hole that the filament has to make a large bend to get around it.  So I will try to fix this while I wait for my new old-style extruder to arrive.

RE: MK3S stops extruding mid print (filament grinding)

Mine was too but all I had to do was release the 3 bolts that held the plastic piece to the extruder motor and move it over then retighten them, unfortunately that didn't fix the clogging issue for me.

RE: MK3S stops extruding mid print (filament grinding)

I've just successfully printed a beautiful vase.  Yes I know, no retractions made it easy to print, but the point is, it printed. 

Here's what I did:

• Separated the heat block, nozzle, heat break, ptfe tube, and heat sink. 
• Put some cpu paste on the top of the heat break, and the nozzle.  I assume we want a hot nozzle.  I did not put any paste on the bottom of the heat break. Since we'd prefer to minimize heat transfer there.
• Inspected all parts for clogging / damage.  None found EXCEPT for the nozzle.
• Put the nozzle on my electric stove and turned it up to bright red.
• Let nozzle cool, then inspected.  All clear.  Cleaned out any burned stuff with airbrush cleaning brush.
• Reassembled everything according to common instructions.

Printed successfully... though at this point that was yesterday and who knows what today holds.  I suspect the parts were incorrectly assembled at Prusa, leaving a gap between the nozzle and heat break where plastic built up and clogged.  That gap is now gone.

Oh and I did scoot the extruder motor to the left about .5mm and now it lines up with the hole nicely.

RE: MK3S stops extruding mid print (filament grinding)

Nice! Not sure it is possible to have a gap internally in the hot end between the nozzle and the heat break since they will butt up against each other before they tighten all the way? However the do recommend a gap externally between the nozzle and the hot end.

https://help.prusa3d.com/article/cto24vjaps-heatcreep

Extruder assembly

Gap between the nozzle and the heatbreak

In all assembled E3D v6.1 hotends, there should be a gap of about 1 mm between the heater block and the hexagonal head of the nozzle. Again, this is to control heat flow inside the hotend. When screwing your nozzle into the heater block, you should tighten it all the way in, but never try to (over)tighten it so that the nozzle head would touch the heater block.