Material feed mechanism rubs off filament

[3design 0]

Before changing the filament the printing went absolutely well, as what concerns the extruder, and the feed mechanism.

Now I manally inserted a new filament, and used the ulticontroller function (prepare/move axis/extrude) at the end. First it works, but before the filament gets into the heating unit, it blocks somewhere and the feeding mechanism grinds off material from the filament. Such, the filament gets too thin to be transported well, the feed mechanism fails. As well, mechanically pushing forward the filament doesn't work because it seems to be blocked totally.

How can I fix this?

PS. extruder temperatur was set to 220, then to 180, which changed anything. The previous filament I took out by heating the noozle to 220, and then pulling it out manually.

[IRobertI 521]

If you have used the filament in the printer before did you snip off the last couple of centimeters off the end? If you didn't the filament can be a bit thicker there and gets caught in the transition between the bowden and the hotend.

It could also be that some of the old filament got left behind as you pulled it out and is blocking the way for the new filament. Look through the side of the tube and see if you can see any junk sitting in there.

Or if you're really unlucky you've developed the dreaded plug. Which hotend do you have, v1 or v2?

[3design 0]

I used the second filament for the first time, and it didn't look thicker (it was a piece cut off from a roll that was already in use before). In contrary, sometimes it was thinner (kind of grazed).

The filament actually gets caught in the Bowden, but far beyond the hotend, sometimes 5 or even 10 cm before.

I didn't see any old filamend remainder (it was red, and easily visible).

As for the hotend version, I suppose it is the v2 (where can I check this?)

I ordered and assembled the Ultimaker in November/December last year.

Printing with the red filament went flawless - as for the feed, don't ask me about other beginner's troubles ;-)

Update: I inserted again the red filament, and it went in much more smoother than the second one (it's "glow in the dark", but I can't tell from which supplier). Such, the problem seems to be the filament itself.

Is this just "bad luck" as for the choice of the filament, or can you fix this in a way?

[IRobertI 521]

Measure the diameter of the filament with calipers on several spots to see that it isn't too fat. Remember to check in two directions in case it's oval.

I also recall there being a bad batch of bowden tubes, the inner diameter was too small. I don't remember when this was though, I'm sure someone else will chime in.

The reason I asked about the hotend was in case you had a plug. Since the filament stops before even getting to the hotend that's not the case. But for future reference it looks like this:

https://shop.ultimaker.com/en/parts-and ... grade.html

 

[3design 0]

You were right, Robert; I'm quite sure that the differing diameters are the issue causing the trouble.

The red filament (which worked flawless) has an oval diameter, varying between 2.76 and 2.93mm (three measurements), whereas the"glow in the dark" filament is between 2.91 and 3.04 mm.

I'd be glad for an input, if such diameters are suitable at all for an ultimaker - what do you think?

[msurunner 2]

You might be able to get away with the larger diameter by turning up the temperature a little bit so there is slightly less resistance in the hotend. Generally speaking, you want to try to stay away from anything over 3mm, but there is a little bit of leniency in the bowden. You would want to make sure you are giving the filament some additional time to loosen up and lose it's spool memory rather than just straight of the back of the machine. I'd say give it a go though. What's the worse that can happen? You get a plug and have to disassemble the hotend.

[3design 0]

The problem is that i even don't get the filament until the hotend. I can push it manually as hard as I want, it stucks somewhere earlier in the bowden tube. I tried to straighten the filament manually with virtually no effect on the smoothness of running.

[msurunner 2]

You are probably out of luck on it then :( The only thing you could really do is try to swap in a section of 4 mm ID tubing for most of the bowden tube, with a smaller section of the original bowden at the hotend. Several people have done it, but you have to have cajones to cut apart an otherwise working bowden tube and splice in an unknown.