It snaps with little effort, almost always along a layer.
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:1Temperature2Flow
- 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
- Damp filament gives brittle parts: dry it.
- A crack on a single layer can be a partial clog that stopped the plastic for a while: clean the nozzle before touching settings.
- ABS, ASA and nylon crack in cold air: enclosed printer and no drafts.
- A part is weaker between layers than along them. If you can, turn it on the plate so the load doesn't pull the layers apart.
Then, in the slicer (in this order)
- Nozzle temperatureFilament › FilamentIf the layers come apart, the nozzle may be too cool for that filament: raise it 5 °C.
- Outer wall speedProcess › SpeedSlower on the walls, each bead has more time to weld to the layer below. For ABS, Bambu suggests 100 mm/s on the outer wall and 150 on the inner ones.
- Maximum fan speedFilament › CoolingToo much air also splits layers. Check in the preview how much fan the walls get; with PETG or ABS, lower the maximum (and the minimum) fan speed.
- Number of wallsProcess › StrengthWalls add more strength than infill: 3 or 4 on parts that take a load.
- Infill densityProcess › Strength15–25% for almost everything; more only where screws go.
Fixed by calibrating:1Temperature2Flow
Tried everything and it's still the same? Calibrate your filament with the 8 tests, or write to us with a photo.