Filament breaking during longer prints

[Blizz 53]

I've had my UM2 for about a week now and printed a lot of smaller objects (up to 4 hours print time) without (much) issues. However I'm trying to print a bigger object (24 hours) and it's happened twice already that when I get up, the printer head is just waving around in mid air because the filament broke.

The coil is not stuck as far as I can see, if I pull on the wire it doesn't seem to require more force than before.

It also doesn't seem to be a "grind" as the break was clean (the first time, I haven't had time to check this morning). But it did break exactly on the feeder sprocket twice. I am using the transparant PLA from Ultimaker for this print.

Any ideas/pointers? Also, how can I get the filament out from the bower tube, last time I've just pushed other filament behind until the broken piece was gone but it took half an hour or so.

 

[gr5 2,265]

Also, how can I get the filament out from the bower tube, last time I've just pushed other filament behind until the broken piece was gone but it took half an hour or so.

 

I've never had this problem but I would remove the bowden from the test head and push it out through the feeder. Be careful. On the print head there is a little clip - remove that clip. That clip holds up the "bowden holder". The bowden holder has 4 metal blades that dig into the bowden. Loosen the 4 thumb screws on the head so that the head is loose - maybe 2mm or enough so that the bowden is loose. Then push down on the bowden holder and pull up on the bowden. Be careful as the metal blades can scrape the bowden and it might not hold well next time. If you do damage the tube just cut off the bottom 1mm of the bowden and put it back in. Tighten the 4 screws last so the bowden is good and tight.

 

[gr5 2,265]

as the break was clean

 

Where do you see the break? Inside the bowden?

Some people rewound their filament onto a tighter reel, or simply dried the filament too much by putting it in a box with desiccant for a week. And then later the filament shattered into hundreds of short pieces. Could it be your filament was too dry? Or too old?

I'm guessing you have "bad" filament and should order some more.

 

[Dim3nsioneer 558]

I only had this issue with cheap filament, never with quality filament like Colorfabb, Faberdashery or DiamondAge.

 

[IRobertI 521]

Where do you see the break? Inside the bowden?

Some people rewound their filament onto a tighter reel, or simply dried the filament too much by putting it in a box with desiccant for a week. And then later the filament shattered into hundreds of short pieces. Could it be your filament was too dry? Or too old?

I'm guessing you have "bad" filament and should order some more.

 

Correct me if I'm wrong but I don't think filament can really be too dry. As far as I know the reason it shatters when re-wound on a spool while "moist" and then dried is because it shrinks slightly causing tremendous stress on the filament which eventually cracks it.

 

[Blizz 53]

The filament was from Ultimaker itself and I bought it with the printer. It did break in the feeder but I didn't have the impression it was ground down. I've printed the piece with silver PLA and that did work, which suggests there is a quality issue with the transparant filament I received.