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Mat Hess
(@mat-hess)
Active Member
Filament Grinding

I have a strange filament grinding problem.

My prints starst off wee but after 3 - 10 mm printing height, the filament is ground and the printer continues printing in mid air without extruding any filament at all. The surface of the printed parts has some fluffy filament filament spots on the surface.

I tried to 

- loosen or tighten the extruder springs

- use a different nozzle to see if it was clogged

- set the extruder notched wheel exactly over the hole

- use a different slicer

- use different layer heights

Any further ideas I could try?

Posted : 06/05/2019 7:21 pm
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(@)
Illustrious Member
RE: Filament Grinding

Does the model have lots of separate areas where the printer needs to hop from spot to spot? Lots of retractions and z-hops exposes a problem with the stock Prusa version of the E3D-V6 heat break.  It has a step at the hot-zone to cold-zone interface that seems to cause filament jams.  Raising print temp 20c can help reduce occurrence, but doesn't cure it.

If you pull filament after a jam, you can measure the fat spot at the end and if it measures 2.2 mm, you've identified the issue.  I new stock E3D-V6 heat break will help that situation.

If the part is simple, not a lot of hopping going on, just linear runs around the perimeter and infill, it's probably something else.

Posted : 07/05/2019 3:09 am
Robin
(@robin-4)
Estimable Member
RE: Filament Grinding

Have you tried a different filament?

As said about the heatbreak its a problem for some filaments but not others. I have this problem with a new filament from a supplier i have always used but it is a new product. I am now waiting for a new heatbreak.

Posted : 07/05/2019 3:25 pm
Mat Hess
(@mat-hess)
Active Member
Topic starter answered:
RE: Filament Grinding

@tim-m30 When I remove the ground filament from the extruder and measure the thickest section, which is 64mm away from the grinding mark,  my caliper shows 2mm thickness. Is this a normal value?

This post was modified 3 years ago by Mat Hess
Posted : 08/05/2019 6:49 pm
Mat Hess
(@mat-hess)
Active Member
Topic starter answered:
RE: Filament Grinding

Tried to print a Benchy today, the pre-sliced one that is included with the prusa software. Same issue. Filament is ground and printer continues printing in mid air after printing fine for 11 mm. At least this issue is easy to reproduce. Printer considered broken at this point... 😥 

Posted : 08/05/2019 8:07 pm
Mat Hess
(@mat-hess)
Active Member
Topic starter answered:
RE: Filament Grinding

I just pulled out another ground filament from the extruder. Found something which I found remarkable:

  • The Filament is much longer than I expected. 
  • The distance between the location where the extruder gear has ground a groove into the filament and the thickest part of the filament is 64mm. This should be where the filament ends because there should be a 0.4mm bottleneck because of the nozzle, right?
  • Instead, the filament continues in another tail of 82mm length.

I have absolutely no Idea where this Tail comes from, I am clueless. Any ideas?

Posted : 08/05/2019 8:44 pm
Robin
(@robin-4)
Estimable Member
RE: Filament Grinding

What is the make and type of filament and is it old or new

Posted : 08/05/2019 10:12 pm
Mat Hess
(@mat-hess)
Active Member
Topic starter answered:
RE: Filament Grinding

The filament manufacturer is DasFilament.

Type PLA black

Age: 2 Months

Posted : 09/05/2019 4:28 am
Mat Hess
(@mat-hess)
Active Member
Topic starter answered:
RE: Filament Grinding

I managed to print a complete 3dBenchy. I tried something I never did before. I left the door of my enclosure open. 

I used to print mostly PETG and always closed the enclosure. I also used to print PLA with the doors closed. 

My theory goes like this 

closed door -> warmer environment -> softer filament -> more likely to kink or be abrased

Might this be the solution ?

Posted : 10/05/2019 8:39 pm
bobstro
(@bobstro)
Illustrious Member
RE: Filament Grinding
Posted by: mat.hess

[... ] My theory goes like this 

closed door -> warmer environment -> softer filament -> more likely to kink or be abrased

Might this be the solution ?

Absolutely. Ambient temps are important with an air-cooled system. The E3D V6 hotend is rated to work in ambient temps up to 40C. Above that and you're likely to have heat-related problems.

Putting on fan covers and goodies that impede airflow is another over-looked cause of heat problems.

Expect to see a spike in heat-related posts as many owners move into hot summer months. I've put a dump of extruder and hotend troubleshooting notes here

My notes and disclaimers on 3D printing

and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan

Posted : 11/05/2019 11:53 am
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