How do you sand balsa wood for a bridge?
Which sandpaper to use, how to sand flat faces and angled ends without rounding them, and how to sand joints until they fit.
Updated · 1 min read
Short answer: sand on a flat block with fine paper, in light strokes along the grain, and stop as soon as the joint fits. Over-sanding rounds the edges, loses weight you need, and spoils the fit.
- Use fine sandpaper, around 220 grit or finer. Coarse paper tears the soft surface.
- Wrap the paper around a flat block, or glue it to one, so the face stays flat. Sanding by hand in the air rounds the corners.
- Sand along the grain, with light pressure.
- For ends, hold the stick against a stop so the angle stays the same on every copy.
- Check the fit often. Hold two pieces to the light. Remove only the high spots.
- Brush off the dust before gluing. Dust on a face weakens the glue.
What not to do
- Don't sand the whole bridge to save weight. It removes little and weakens the faces.
- Don't round the ends of sticks that need to meet flat.
- Don't sand after the glue is on.
See cutting joints by hand and gluing joints.