How to prevent filament tangling
Filament tangling is a occasional problem that has happened to every one of us at least once, especially to those who are new to 3D printing. You would think if print started fine and then couple of hours later stopped due to a tangled filament, that it must have been a bad wound from the factory. Let's learn what is actually causing the tangle and how to prevent it.
Bad wound from the factory?
Filament is a single continuous string on the spool. Take a piece of string or filament, hold both ends and try to make a knot or tangle it without ever letting go of either end. Now if you think about it and pretend that one end represents the filament coming out of the extruder, the other represents the filament that is already wound on the spool, it is not possible to tangle it in the factory.
How tangles really happen and how to prevent it?
The end of the filament slips underneath of another coil/loop when the end is not secured is the short answer. When you receive your filament, its end is secured/weaved through the holes on the edge of the spool and that is not only for the shipping purposes. If you let the end loose, tension will cause it to uncoil loosely on the spool, slip underneath another coil and this is where a tangle happens. Similar scenario can happen when changing the filament, moving it between printers or leaving it in the shelf loose without a proper tension.
When your print fails and you see a knot at the end of your filament spool, it is very important to remove the knot completely and not just uncoil little bit of filament and restart the print. To get the knot completely out, you need to unwind complete loops of filament until you see uniform paths of filament coming off the spool. When done you should have the tangle off the spool, unless you have multiple tangles on it. Then simply rewind the filament back on the spool and make sure you maintain a proper tension and secure the end of the filament through a hole on the side of the spool.
To prevent this from happening again, make sure the end of your filament is secured/weaved through the holes on the edge of the spool when you are not using it. Maintain a good tension and do not let the filament uncoil loosely when you are feeding it into the printer or moving it for filament changes. This applies to any filament brand.