I've been playing with some filaments recently that are extremely brittle and take very little to snap (mostly translucent, colored ones). A minor kink in the filament, combined with high speed / high frequency infill is enough to make it snap mid-print, usually on longer prints. Sometimes within the extruder, sometimes above it (usually within).
I've tried printing out the large herringbone gear for Wade's three times now, all three a failure, due to filament snapping in the middle of the print job. It's starting to get more than a little annoying at this point...
Does anyone have any ideas on how to prevent it, apart from the obvious (switching to a different filament)?
Thing is, those very same, brittle filaments also tend to cool very quickly for some reason, which makes them perfect for overhangs, things like gear teeth etc. Also, the chances of snapping are directly proportional to the length of a print job, so i wouldn't say it's something cause by, say, pressure / extruder rate requirements or anything similar. And yes, i've tried loosening the idler on the extruder as much as i'm comfortable with. I don't think loosening it any more would help much.
Edit: Tried hanging the filament loop on a desk lamp and giving it the gentlest possible approach too. Didn't help. I think the problem is compounded by the fact the loop of filament i had seems to have been taken from the end of a reel, so the radius of the loops is pretty small and curvature is huge.