Bridging: printing across open space
Bridging means extruding lines between two supported areas without support directly underneath. Short bridges can print surprisingly well, while longer spans increasingly sag. Important variables include span length, cooling, speed, material and slicer bridge settings.
Bridging is not the same as an overhang
Bridge: material spans between two support points. Overhang: each new line extends sideways beyond the previous layer.
Span length matters
Longer unsupported spans are harder to print cleanly.
Cooling
Bridging often benefits from strong cooling so the filament stabilises quickly. But cooling requirements vary by material.
Speed
Too fast: poor anchoring. Too slow: more sagging can occur. Use tested printer/material profiles as a starting point.
Design out the bridge
Possible alternatives:
- rotate the part
- redesign the opening
- use a chamfer or arch
- split the part