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Weird black fabric looking bits in my prints

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I'm quite new to UM2 and have noticed these weird blackened fabric looking fluff-bits among the plastic material in my prints.

First I thought it was a problem with the initial PLA roll that came with the UM2 but now I've got some new stuff from Colorfabb and saw the same weird fluffy bits in the new prints also.

There is usually like a one black flake of this stuff in an average print.. Doesn't happen every time though... The fluffy bit sticks out from the print and is soft... like cloth or napkin etc... Could it be some sort of material impurity?

I can trim it away but some of it stays "in" the material and leaves a black stripe. Unfortunately I don't have a picture of it now as I just cut them of from my last nights prints.

Anyone come across anything similar?


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I'm thinking it could be one of two things.

1) Dust/crap on the filament

2) Or perhaps it's a symptom of the rubbing we've been seeing in the feeder. The filament rubs on the internals of the feeder, which is made out of ABS, and grinds parts of it down. It's possible that some of this dust is getting into your prints. Ultimaker are working hard on addressing this problem. (and a few of us here on the forums are working on new designs as well)


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I suspect #2 and it's a serious problem because that black ABS can clog your nozzle slightly and degrade the extrusion ability at faster speeds. I recommend you move the filament on to the floor for now until UM has a new feeder:

Having the filament come in at a more vertical angle can help this if the problem is mostly at the entrance to the feeder but if the problem is elsewhere then it won't help:

spool On floor


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