The lines stretched through the air between two supports droop or break.
It happens on any FDM printer. Setting names are Bambu Studio's: in Orca Slicer almost all have the same name, and PrusaSlicer or Cura usually have an equivalent.
Where do I start?
Two questions to sort out what to check. It's a guide, not a sure fix: every printer and every filament is different.
Check in this order
- The printerIf it printed fine yesterday and not today, it's almost never the profile. Check the plate, the nozzle and the room: printing at 15 °C is not the same as at 30 °C.
- The filamentA spool that has soaked up moisture gives strings, bubbles and brittle parts. Dry it before changing settings, and pick that filament's profile in the program.Filament pages
- The quick checksThe “First” list below: it's the fastest to check.Go to “First”
- The slicerOnly now, the settings below, in order. Change one thing, print a small test and compare. If you change three at once and it gets fixed, you won't know which one did it.Go to the settings
Check in this order
- The quick checksThe “First” list below: it's the fastest to check.Go to “First”
- The filamentA spool that has soaked up moisture gives strings, bubbles and brittle parts. Dry it before changing settings, and pick that filament's profile in the program.Filament pages
- The testsCalibrate your filament with these tests:7Overhangs and bridges
- The slicerOnly now, the settings below, in order. Change one thing, print a small test and compare. If you change three at once and it gets fixed, you won't know which one did it.Go to the settings
Check in this order
- The quick checksThe “First” list below: it's the fastest to check.Go to “First”
- The previewStep through the slicer preview layer by layer: that's where you spot missing supports and odd areas in this part.
- The slicerOnly now, the settings below, in order. Change one thing, print a small test and compare. If you change three at once and it gets fixed, you won't know which one did it.Go to the settings
First
- A short bridge always comes out better than a long one. If you can, turn the part on the plate so the gap is crossed the short way, or add a support in the middle of the span.
Then, in the slicer (in this order)
- Bridge flowProcess › QualityFirst: in the air the strands come out round and may not touch each other. A little more flow joins them; a little less makes them lighter. Test it with your filament and profile: Bambu's wiki links a test model.
- Bridge speedProcess › SpeedOn long bridges, go down to 30 mm/s. Slower isn't always better: go down 10 mm/s at a time and compare.
- Force cooling for overhangs and bridgesFilament › CoolingHave the fan go up on bridges (on by default). If it's off, turn it on.
- Bridge directionProcess › StrengthIf the program laid the bridge the long way, set the direction so it crosses the short way.
- Thick bridgesProcess › QualityRound, thick beads that hold longer bridges, with a rougher underside. On short bridges, better off.
Fixed by calibrating:7Overhangs and bridges
Tried everything and it's still the same? Calibrate your filament with the 8 tests, or write to us with a photo.