Clogs part way through a print (heat creep)
The print starts fine, then extrusion fades out after half an hour or more, often on slow, small or detailed prints.
Also described as clogs mid print, stops extruding halfway, jams during print, heat creep, extrusion stops
Try these in order
Most likely and quickest to check first. Change one thing at a time so you know what fixed it.
Hot end cooling fan not working well
Heat travels up the hot end and softens the filament before it reaches the melt zone, so it swells and sticks.
- Check the hot end fan spins all the time while the nozzle is hot, and clean dust off the heatsink.
- Check the fan duct and shroud are fitted properly.
Too much retraction
- Lower retraction distance, especially on direct drive printers (under 2 mm).
Hot enclosure with PLA
- Open the lid or door of an enclosed printer when printing PLA.
Hot end left hot while idle
With nothing flowing through, heat soaks up into the filament sitting above the melt zone, so it softens and jams when printing starts again.
- Don't leave the nozzle hot for long between prints, or retract the filament a few millimetres first.
- If you pause a print for a while, lower the nozzle temperature and reheat it before resuming.
Gap in a Bowden hot end
- Make sure the PTFE tube is pushed right down to the nozzle with no gap.