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[Rozwiązany] Underextrusion issue  

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Kevlad
(@kevlad)
Eminent Member
Underextrusion issue

Hi all, Im having an issue with printing anything other than PETG or PLA on tool 1.  Im having the problem with Flexfill 98a and PA-CF but to narrow it down Im focussing on the 98a first....

Im trying to print Filametum Flexfill 98a and it prints perfectly on tool 2 and I change to T1 in the slicer and send the same job with the same settings, either nothing extrudes or its thin whisps.  Even when you purge the material, it flows smoothly out of T2 and stutters from T1.  To me the material cannot be the problem as it works on T2.  It feels like the 

Both T1 and T2 print PLA or PETG with no issues.

What I have tried:

Drying filament (just to rule it out) - prints on T2, doesn't print on T1 - so cannot be a problem with the filament

Loosening tensioner (a little and then a lot....) - no change

Tightening tensioner (a little and then a lot....) - no change

Taking the Nextruder apart to see if something was damaged (didn't see anything different from T2)

Changing nozzle from brass to ObXidion - same output

Disabled the side filament sensor and put the spool directly behind the printer for a straight shot into the PTFE tube and to reduce drag - no change. 

 

Pic below for reference...

Any ideas?

Opublikowany : 28/06/2024 11:27 am
Eef
 Eef
(@eef)
Reputable Member
RE: Underextrusion issue

I do not have an XL, so do not know exactly how it works there, but I would check if the tensioners are well tightened to there axles

We will do what we have always done. We will find hope in the impossible.

Opublikowany : 28/06/2024 11:31 am
Kevlad
(@kevlad)
Eminent Member
Topic starter answered:
RE: Underextrusion issue

Quick update....  if I disconnect the PTFE tube from its connector and manually push filament down into the extruder, material flows and the print improves.....  this would indicate that the gear that pulls the filament down is not 'grabbing' the filament?  Ive cleaned the gear wheel just in case it had something on it but no change.  Turning the spring loaded tensioner arm screws in either direction has no effect.... I'm stumped.... 

Opublikowany : 28/06/2024 4:03 pm
Eef
 Eef
(@eef)
Reputable Member
RE: Underextrusion issue

I am not familiar with the xl , but is sounds that the mechanism (gearbox) what is pushing the filament trough the nozzle is not functioning correct. 
Check if there are screws what needs more tightening so the motor keeps turning the gearbox. 

We will do what we have always done. We will find hope in the impossible.

Opublikowany : 28/06/2024 4:19 pm
Kevlad
(@kevlad)
Eminent Member
Topic starter answered:
RE: Underextrusion issue

Thanks Eef - I had the extruder in pieces earlier and I double checked everything and I can see the gear turning when its printing if I release the idler....

I think my assumption (and your thinking) was correct though - something isn't right with the mechanism that pulls filament....  Ive just printed a modified idler lever from Printables Nextruder Modified Idler Lever by Uko which closes the gap between the tensioner and the gear more than the original Prusa part.  First coupe of layers have actually went down great for the first time ever on T1.  Im going to let it run the test print but fingers crossed this may be resolved....  until I try PA-CF tomorrow... 🤣 

Opublikowany : 28/06/2024 5:31 pm
Eef
 Eef
(@eef)
Reputable Member
RE: Underextrusion issue

.....We will find hope in the impossible.

We will do what we have always done. We will find hope in the impossible.

Opublikowany : 28/06/2024 6:12 pm
Diem
 Diem
(@diem)
Illustrious Member
RE: Underextrusion issue

if I disconnect the PTFE tube from its connector and manually push filament down into the extruder, material flows and the print improves.

Is the PTFE tube kinked?

Is there dust or debris in the tube?

Have you been using abrasive filament that has roughened the inside of the tube?

Has anything sticky dropped onto a filament and then been dragged into the tube?

Cheerio,

Opublikowany : 29/06/2024 10:35 am
Kevlad
(@kevlad)
Eminent Member
Topic starter answered:
RE: Underextrusion issue

Hi Diem - no, no, no and nope.... 🤣  

Im going to mark this one as solved.  The part by Uko (earlier post) has worked.  Filament is now being pulled down into the nozzle.  I had to disable retraction and up the temp by a few degrees to stop the TPU from getting stuck in the gear but it's just done a 3 hour print with no issues or interventions.  

Thanks all.

Opublikowany : 29/06/2024 10:54 am
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