RE: Spool bouncing
If that's a carbon fiber filament (or other type of very stiff filament) then this can happen. For these types of filaments, I print directly from my dry box instead of mounting the spool.
RE: Spool bouncing
Actually, it's a basic spool of standard PLA filament
RE: Spool bouncing
Actually, it's a basic spool of standard PLA filament
Never had that happen with softer filaments. My guess is perhaps it wasn't wound well to begin with? I've found this to be the case with cheaper filaments.
RE:
I'm going out on a limb here, but based on personal experience, here's my theory.
If the extruder filament drive & idler gears and filament aren't centered together, extruding will twist the filament and cause it to hop off the reel. This can happen with most any toothed extruder.
Easiest is to check the two idler pressure screws are equal and the idler latch isn't binding and torquing the idler at an angle. Also visually check the filament is in the middle of the teeth on the gears. If a gear is set too high or too low on the motor shaft, the filament rides a sloping track and twisting is pretty likely. Why? filament rides one gear at one radius, and the other gear at a different radius, and the two different speeds imparts a torque that twists the filament. Over several meters, this twist adds up and gets back to the spool, eventually causing filament to hop over the edge.
RE:
@hyiger is right. The windings on the spool are wound too loosely.
@Tim is wrong: If there was a torque effect, the loose windings outside the spool would be turned above or underneath the spool like a spring.
RE: Spool bouncing
@hyiger is right. The windings on the spool are wound too loosely.
@Tim is wrong: If there was a torque effect, the loose windings outside the spool would be turned above or underneath the spool like a spring.
Then what force is lifting the filament into the air above the spool? If there is no torque on it, it'd be hanging loose when off the spool.
If filament is wound loosely it's possible for the end under tension to pull between other turns and jam slightly. When such a jam pulls free the tension imparts spin to the spool and it turns perhaps a quarter turn under its own momentum - filament is not very compressible so the next turn lifts above the outer layer and passes some of the pressure on to the next turn and so-on so that several turns no longer fit the spool and can sometimes slip sideways.
This is closely related to the 'bird's nest' tangles experienced by novices learning to cast with some types of fishing reels.
Cheerio,
RE: Spool bouncing
If filament is wound loosely it's possible for the end under tension to pull between other turns and jam slightly. When such a jam pulls free the tension imparts spin to the spool and it turns perhaps a quarter turn under its own momentum - filament is not very compressible so the next turn lifts above the outer layer and passes some of the pressure on to the next turn and so-on so that several turns no longer fit the spool and can sometimes slip sideways.
This is closely related to the 'bird's nest' tangles experienced by novices learning to cast with some types of fishing reels.
Cheerio,
I'm going to agree with this. I had the filament bind up once. The windings on the spool were clearly poorly wound and loose.
Regards,
Mark
RE: Spool bouncing
Thanks guys,
I believe this is the case. I need to buy better quality material.
Meanwhile I made some movable magnetized post to keep the spool from bouncing (see picture). It's not pretty but it works.
RE:
As an aside, the friction of the spool on a solid plastic bearing surface adds the spooling issues. I haven't done it for the Core spool yet, but for my other printers I've made spool holders with bearings that prevent the snap back unspool in the first place. Worth noting, they still suffer the filament twisting due to extruder alignment issues.
RE:
Thanks guys,
I believe this is the case. I need to buy better quality material.
Meanwhile I made some movable magnetized post to keep the spool from bouncing (see picture). It's not pretty but it works.
Nice! I had issues with the spool coming off the post, so I printed this: Prusa CORE One Bearing Spool Holder which works well for me.
RE: Spool bouncing
One annoying thing is when the filament bound up on the spool it pulled on and mangled the PTFE tube:
grrrrr!
Regards,
Mark
RE: Spool bouncing
My solution works also 😊
https://www.printables.com/model/1385280-cofts-prusa-core-one-filament-tangle-stopper
RE: Spool bouncing
One annoying thing is when the filament bound up on the spool it pulled on and mangled the PTFE tube:
grrrrr!
Regards,
Mark
I printed one of these which is a big help: Prusa Core One Filament Guide