Super Fine string when changing filament? Under extrusion issues as well

[mikebaier 0]

Hey everyone,

Having a strange scenario whenever i change filament in a UM2

After the filament ejects there is a super fine strand of filament left in the bowden tube and still attached to the end of the 2.85mm end of the filament.

I can carefully pull on this for what seems like it is much longer then actual length of the bowden tube.

Is this an indicator of a bad coupler or other part?

Any ideas what would cause this or is this completely normal? I don't remember this happening when the printer was brand new.

The printer itself is only a couple months old now and I've only printed with PLA.

I'm also suffering from under extrusion issues.

Thanks for everyone's time it's greatly appreciated!

-Mike

 

[gr5 1,270]

I recommend you don't use the normal "change material" and instead do a cold pull on every material change. That's what I do:

http://umforum.ultimaker.com/index.php?/topic/4118-blocked-nozzle/?p=33691