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Difficulty unloading filament from Bondtech extruder  

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Detig
(@detig)
Active Member
Difficulty unloading filament from Bondtech extruder

I've installed a Bondtech extruder (IFS version) on my Mini recently and have some trouble unloading filament with it getting stuck often and requiring a forceful tug to get it out of the extruder. In the last attempt it snapped so the I'm going to take the extruder apart. Any ideas or recommendations on what to look for?

Posted : 22/01/2022 4:11 pm
BogdanH
(@bogdanh)
Honorable Member
RE: Difficulty unloading filament from Bondtech extruder

What exactly happens when you unload? I mean, when you took extruder apart (to free the filament), what did you see? Not enough filament extruded (filament remains between those two gears)? Or is there some blob at the end of filament, which prevents filament to come out between two gears in extruder?
Btw. I'm using same extruder for months and that never happened to me -just saying.

[Mini+] [MK3S+BEAR]

Posted : 22/01/2022 8:48 pm
Detig
(@detig)
Active Member
Topic starter answered:
RE: Difficulty unloading filament from Bondtech extruder

Just pulled it out and there is indeed a blob at the end of the filament, stuck before reaching the gears on the side of the intake/filament sensor. I have had trouble pulling filament out before (both PLA and PETG), this is just the first time I had to take the extruder apart for it.

So why is the blob forming? Am I unloading filament too quickly after finishing a print or the other way around?

Posted : 23/01/2022 11:12 am
BogdanH
(@bogdanh)
Honorable Member
RE: Difficulty unloading filament from Bondtech extruder

So why is the blob forming? Am I unloading filament too quickly after finishing a print or the other way around?

No, blob can't/shouldn't happen by any user action (at unloading filament, in this case).

The problem is hotend. Or more precise: heatbreak.. or even more precise: because of heat, PTFE tube inside heatbreak became slightly shorter over the time (I assume that hotend is assembled properly, of course).
To spare you with explanations and to keep post short... Take hotend apart, check inside heatbreak (clean it if needed), check PTFE tube length and replace if necessary.

[Mini+] [MK3S+BEAR]

Posted : 23/01/2022 3:30 pm
Detig
(@detig)
Active Member
Topic starter answered:
RE: Difficulty unloading filament from Bondtech extruder

That's the interesting thing. The hotend side is entirely new: new nozzle, heaterblock and heatbreak (brozzl - titanium). And yes, I made sure to push the block upwards while cold tightening but it is possible it slipped a bit when I hot tightened as I had to reposition it a bit.

And the blob happened with the previous setup as well (stock heatbreak) although for that one I assumed time had come to change the ptfe tube and decided to simply replace the heatbreak.

As for the blob as you can see it is not massive, just a slighlty enlarged bulb of material.

Posted : 23/01/2022 5:11 pm
BogdanH
(@bogdanh)
Honorable Member
RE: Difficulty unloading filament from Bondtech extruder

Blob happens in heatbreak and the reason is (usually) gap between heatbreak and PTFE tube at the bottom. Brozzl doesn't specify the length of PTFE tube, so what length did you use? Brozzl heatbreak seems to be a Bondtech clone, so I assume it should be 36mm (with chamfer on both sides)

Anyway, your blob doesn't look that big and I would think it should pass trough extruder gears. Maybe you should reduce filament tension, so gears would increase gap easier to let blob trough.

[Mini+] [MK3S+BEAR]

Posted : 24/01/2022 8:11 am
Justinline
(@justinline)
Active Member
RE:

I'm having a similar issue when loading and unloading filament with the Bondtech IFS extruder.  The extruder motor makes a high pitch noise and the gear freezes up when it tries to move more quickly.  But when it's going slow during the initial load or unload, it's fine.  It also prints just fine.  But it'll take several iterations to get the filament loaded or unloaded.  Not sure if these issues are related.  See the video linked here that shows the gear's behavior.  The door is open for viewing purposes, but the same thing happens with the door closed.

Note: I switched back to the stock Prusa extruder and the filament loaded/unloaded without issue.  Also, I tried to pass more current to the extruder as suggested by Bondtech support, but that didn't help either.

Any insight is appreciated.  Thank you.

This post was modified 3 months ago by Justinline
Posted : 08/02/2022 8:02 pm
Detig
(@detig)
Active Member
Topic starter answered:
RE: Difficulty unloading filament from Bondtech extruder

Can’t really help you there, managed to solve the unloading issue with mine after reseating the hotend (I assume).

Posted : 19/02/2022 9:49 pm
JeffB
(@jeffb-2)
New Member
RE: Difficulty unloading filament from Bondtech extruder

 

Posted by: @justinline

I'm having a similar issue when loading and unloading filament with the Bondtech IFS extruder.  The extruder motor makes a high pitch noise and the gear freezes up when it tries to move more quickly.  But when it's going slow during the initial load or unload, it's fine.  It also prints just fine.  But it'll take several iterations to get the filament loaded or unloaded.  Not sure if these issues are related.  See the video linked here that shows the gear's behavior.  .[.....]Also, I tried to pass more current to the extruder as suggested by Bondtech support, but that didn't help either.

Any insight is appreciated.  Thank you.

I am also having the exact same issue with my Bondtech. Such a maddening issue.

Posted : 22/03/2022 11:08 am
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