Poor Bridging

Bridging happens when the printer must extrude material across an open gap between two points without any support below. When bridges fail, filament can sag, droop, or string across the span. The techniques to improve bridging are very similar to improving overhang performance, as both require careful control of temperature, cooling, and speed.

To achieve cleaner, more stable bridges, several adjustments can be made in slicing settings and printer setup.

Key Settings and Techniques

• Reduce print speed: Slowing down the print speed gives the extruded filament more time to solidify in midair before it sags. Typical bridge speeds are between 15–30 mm/s depending on filament and gap length.

• Increase cooling fan speed: Rapid cooling helps the filament solidify quickly after extrusion. Maxing out the part cooling fan for bridge sections can greatly improve quality, especially for PLA or other easy-to-cool filaments.

• Lower nozzle temperature slightly: Reducing the temperature by 5–15°C can prevent filament from staying too fluid as it extrudes. The goal is to strike a balance between flow and rigidity.

• Enable bridge detection in your slicer: Most modern slicers, such as Bambu Studio, PrusaSlicer, and Cura, have dedicated bridge settings. These automatically apply slower speeds and stronger cooling when bridging regions are detected.

• Adjust extrusion flow for bridges: Slightly under-extruding on bridges (e.g., 90–95% flow) helps prevent drooping lines and blobs.

• Minimize unsupported bridge length through design: If possible, support long spans with small arch shapes, ribs, or small support tabs in the model.

• Check filament condition: Poor bridging can also result from wet filament. Ensure it is properly dried before printing, as moisture can cause bubbling and inconsistent extrusion.

• Maintain a clean nozzle: Residue on the nozzle tip can pull or drag filament during bridging, leading to uneven lines.

Summary of Ways to Improve Bridging

• Slow print speeds for bridge sections

• Increase part cooling airflow

• Reduce nozzle temperature moderately

• Use slicer bridge settings and tune flow

• Design to shorten unsupported gaps

• Keep filament dry and nozzle clean