How To Cut Balsa Wood

Balsa wood is an easy wood to work with. It cuts easily with an exacto knife. It sands easily. It accepts paint and other finishing products well. Thin boards of many thicknesses are available in most hobby and hardware stores.

Method

Before cutting, draw your pattern on the using a ruler, curve, or other stencil and a sharp pencil.

As with other woods, balsa has wood grain. When cutting with an exacto knife along a pattern line, the grain tends to lead the knife off coarse. To prevent this, tilt your blade and cut from a part of the line that runs across the grain to a part that is more in line with the grain. That way, you will be able to stay on your lines better.

With this in mind, here's how to cut balsa well:

1. Mark the cutting line with a fine line pen or sharp pencil.
2. Begin your cut where the line lies across the grain the most.
3. Do not attempt to cut through the wood, just skim the line on the first pass.
4. Holding the knife so the blade is vertical but slanted forward at a 45 degree (or so) angle, cut along the line toward a place where it runs parallel to the wood grain and stop. If there is no such place, stop at the end of the line.
5. Repeat steps 2 to 4, possibly moving the knife over the line in the opposite direction on parts of the line, always cutting from across the grain to where it is parallel (lined up with it).
6. Repeat steps 2 to 5 pressing deeper into the wood until it cuts through.
7. Collect together pieces of the same dimension or shape and stack them up so along common edges align.
8. Using medium rough sand paper (80 - 60 grit) lightly sand the aligned edges square. If the pieces are to be the same shape, sand them to the same size. If they are slightly different sizes as airfoil ribs in airplane wings can be, you can still shape them all together. Cut out the right number of them using the pattern for the largest size. Cut out only one at the smallest size. Stack them with the smallest on one end. Sand making the largest at one end and the smallest at the other. All the ones in the middle will vary smoothly in size. After shaping, sand each individual part flat on edge if necessary.