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Clogged Bowden tube

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A week or two ago I was bought some filament for my UM2, 3mm filament from ", and I explained that the size should be 2.85 but I checked the diameter to be a very consistent 3mm and decided to give it a go. It managed a lot of decent prints, until I tried a different colour filament bought in the same circumstances, which managed an initial printing and then went bad, extruding terribly.

I have tried all the usual tricks, the nozzle is definitely clear, buildplate and temperatures fine, but the cog at the back for a few trial prints kept grinding into the filament and meaning I had to drag it back and cut it, and insert a fresh bit. The Bowden was very nearly too small, such that dragging it out had to be done manually; then I left the printer to sit off for a while, two or three days.

When I came back to do a trial print, it managed a few dregs, and next I looked, the filament had snapped at the extruder, at the reel and at various points inside the Bowden. I presume it was due to the reel being badly placed (doesn't fit on standard reel thing, made a Lego one), but the tube is now full of bits of filament that won't budge. Is there a way to remove, could I print without, or will I have to but another? If the latter, are there bigger sizes?

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No you can't print without it. It may be sufficient to simply remove the Bowden tube at both ends, and straighten it out and then push some fresh filament through by hand to dislodge the old stuff.

If you need to replace it you can either contact Ultimaker support (support.ultimaker.com), and request a replacement, or buy some 1/4in outside diameter, 1/8in inside diameter tubing from McMaster Carr or equivalent local supplier. I haven't replaced the UM2 Bowden, but I did replace my UM1 tube with a nylon tube with a slightly larger internal diameter (0.15").

However, I strongly recommend that you get rid of the crap filament that you bought, and stick to using good stuff from reliable suppliers. Compared to the cost of the printer, the price premium for decent filament is small - especially on a per-print basis. It will pay for itself anyway in saved time, and avoided damage to your printer.

 

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I've removed it at both ends, but neither hand nor printer can move it at all. Is there any disadvantage to larger bowden? The filament is slightly large but when it worked it made very nice stuff, a good deal of it too. Also, come to think of it, I tried using Ultimaker brand Bronze PLA during the "why won't it work" phase, but that may have failed due to a mildly clogged nozzle, I didn't keep note of what happened when.

 

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The disadvantage of a larger bowden is primarily that you need to use larger amounts of retraction, since there's more slack in the tube, and the first few mm of retraction just shorten the path of the filament within the Bowden, rather than moving the filament back out of the hot end.

 

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Perhaps throwing the whole lot into the freezer for a bit can help? I have no idea what the relationship between amount of shrink between PLA and the bowden is though.

Or, try boiling it to soften things up. I imagine if the softened PLA doesn't get out you will have well and truly clogged it forever if you go that route though :)

 

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Hmm.. I can't find any 1/8 inside diameter, 1/4 out, nearby at a first glance, no Mcmasters in Bristol, so might have to contact ultimaker support, is the 3mm filament really not worth using? I have about 2.4 reels worth, in 3 slightly used colours, and would be loath to part with all the money that cost.

Can anyone assist on the matter of freezing vs boiling?

How reliable is colorfab?

 

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Here's what I would do with the 3mm filament. Take some sheet metal and drill a 3mm hole through it. Then feed all the 3mm filament through it and see how many times it gets stuck. Then throw all your 3mm filament away. Or you can skip to the final step and save yourself some time. At some point you are going to throw it all away. It's just a question of how long it takes you to admit defeat.

 

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Amazon has six Bowden tube fixtures with a long piece of tube for $10, among many other choices. I may be having the same problem; I just bought 6 kilos of Tianse filament. What how good is their reputation? By the way, would improper storage of PLA would allow it to absorb enough moisture to gum up the printer? And can PLA be reconstituted just like silica gel, by putting in a warm oven?

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PLA doesn't absorb water.  You don't have to store it very carefully.  Nylon, PVA are the worst about absorbing water - keep them sealed with dessicant.

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