melted filament jammed in bowden - how to remove?
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On my bowden-equipped delta the hot end fan failed, and wasn't spotted for several hours. Jam resulted. I've managed to extract the bowden from the heatsink (and nozzle from the block, and heatbreak is clear) , but the filament won't shift from the bowden.
In trying, I've snapped the end of filament off, so there's no projecting filament at the hotend end of the bowden.
I've tried pulling and pushing as hard as I can from the extruder end (the limit is getting a grip on the bowden).
So is this bowden a write-off, or is there a clever trick? It's 1.75mm PETG filament and Capricorn XS, if that matters.
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@achrn It's happened to me from time to time when I've been experimenting with various hot end designs. I haven't yet found a way to clear the tube that is quicker and cheaper than simply replacing it. You have also discovered a flaw in the expensive Capricorn tubing in that it blocks more easily due to the tighter tolerances and smaller internal bore. I buy cheap no name clear PTFE tubing which is less prone to blocking and has the advantage that you can easily see the filament inside.
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I might try heating the PTFE tube in the section where the blockage is with a hot air gun in the hope that the filament might soften enough to let me pull it out. Don't go too crazy with the heat as you don't want the PTFE to break down.
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@phaedrux Putting the blocked end into boiling water might be enough with PETG and avoids any damage to the PTFE tube.
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Heating the filament to soften it doesn't work. Assuming there is a bit poking out that you can get hold of, it just parts company and you end up with a chunk of stuck filament inside the tube that you can't get hold of. So you have to push it out. Which means you need something less than 2mm diameter that is long and rigid. If you don't have anything like that to hand, you'll have to buy something, which will likely cost more than a new bit of PTFE tube. But you are still stuck with the problem of how to hold the tube which will buckle or crush easily when it's heated. Which brings me back to my earlier post where I said that it's simply quicker and cheaper to replace the tube.
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Thanks all.
I have in the immediate term ordered more tube.
I thought about heat with a heat-gun (and I have a pretty reliable digital control heat-gun that will go down to 80C so should be able to avoid generating poisons). I hadn't thought of boiling water.
There is no projecting end, so it will be pushing. There's a good chance the new tubing turns up before I get round to tackling it though.
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I should have said no projecing end so it will be pulling from the other end.
Anyhow, I have extracted the filament - I got a flat bit of scrap metal, drilled a 2mm hole and threaded the projecting filament through that, so the end of the ptfe was pressed on the metal, then pulled on the filament using some pliers with fine serrated jaws while holding the metal. Pulling hard but steadily resulted in the filament slowly pulling through.
It was touch and go - the filament snapped a couple of times, fortunately each time leaving some still to grip. Had it snapped within the tube it would have been over.
I think the tube is now out of tolerance - the plug of melted (now solidified) filament material that has been drawn through it measures a hair over 2.1mm, and I can reasonably easily push it back in. I've probbaly converted expensive close-tolerance capricorn to something cheap-and-cheerful. Also, the end of tube got a little mangled , so it's now about 5mm shorter (when I trim off the mangled bit).
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if it happens again dont be scared to spray some wd 40 into the tube this will assist in pulling it out....
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@percar said in melted filament jammed in bowden - how to remove?:
if it happens again dont be scared to spray some wd 40 into the tube this will assist in pulling it out....
..........and how would you then ensure that no trace of WD 40 is left over inside the tube to contaminate the filament and likely cause interlayer adhesion problems. ?
