Sagging bridges

Lines that span a gap between two points droop or break instead of staying straight.

Also described as bridging, bridge sagging, drooping bridge, bridge failing, strands hanging

Try these in order

Most likely and quickest to check first. Change one thing at a time so you know what fixed it.

Not enough cooling
- Set the fan to 100% for bridges.
- Turn on the slicer's bridge settings (usually slower speed and a little less flow).
Bridge too long
- Keep unsupported bridges under about 30 to 50 mm, or add a support in the middle.
Too hot or too fast
- Drop the temperature by 5 °C and try a bridge speed of around 20 to 30 mm/s.
Worn or partly blocked nozzle
If bridges that used to print well have slowly got worse, the nozzle may be worn or narrowed by burnt plastic.
- Do a cold pull, or fit a new nozzle and print the same bridge again.