How to fix a tangled filament spool
A tangle usually announces itself mid-print: the extruder clicks, the print goes thin, then stops feeding entirely. Here is how to get out of it without cutting the whole spool loose.
Fixing it
- Pause the print rather than cancelling, if your printer supports it. Many prints can be rescued.
- Take the spool off and find the crossover point, where one wrap of filament has slipped under another.
- Unwind backwards past the crossing. Do not pull hard. Pulling tightens the knot into the spool sides.
- Free the trapped strand by lifting the wrap above it, then rewind by hand, keeping tension so it lies flat.
- If it will not free, unwind the loose filament into a loose coil on the floor until you are past the knot, then rewind the whole thing. Tedious, cheaper than a new spool.
- Feed it back in, purge until the colour runs clean, and resume.
Why tangles happen
Almost always because the end was released. When you take filament out and let go of the end, the spool springs loose, a wrap slips sideways and slides under its neighbour. Cheap spools with wide gaps between the sides make it far more likely.
Preventing it, permanently
- Never let go of the end. Always clip it into the hole on the spool edge or fold it into a tight bend before releasing.
- Use clips rather than the holes, which put a sharp kink in the filament that later jams the extruder.
- Keep tension while loading so a loose wrap cannot slip under another.
- Watch the first layers after loading a partly used spool, which is when older tangles show up.
- Store spools upright in a sealed box, not stacked on their sides.
The related problem: the filament runs out mid-print
Many printers pause and let you load a new spool. If yours does not, note the layer height where it stopped, and you can sometimes restart the print from that layer by slicing a cut version of the model. Not elegant, but it saves hours of work.
A tangle costs ten minutes if you catch it and a whole print if you do not. Check the spool whenever you hear the extruder click.