How to Cut Masonite With a Jigsaw

Lay a sheet or a board of Masonite siding flat on a pair of sawhorses.

Draw the outline of the cut you want to make on the surface and move the sheet or board so the outline is as close to one of the sawhorses as possible without being directly on top. Clamp the Masonite to the sawhorses with a pair of C-clamps, placing one clamp as close as it can be to the outline without interfering with the movement of the saw and the other on the other sawhorse.

Drill a half-inch hole in the board if you are cutting a shape that will be completely enclosed. The hole should be on the waste side of the outline and just touching it.

Fit a jigsaw with a utility blade meant for cutting wood. Rest the saw on the surface of the board with the blade positioned at the beginning of the outline. Hold it steady with both hands and pull the trigger, then move it along the outline, keeping the base of the saw in contact with the material you are cutting at all times. Keep your eye on the front of the blade so that the saw doesn't wander off it. You may have to stop and periodically clear away dust so that you can see the outline.

Stop and reposition the Masonite if the cut takes you far enough away from the clamp that the vibrations become uncontrollable and begin to hamper your accuracy.

Lightly sand the edge of the cut with 150-grit sandpaper when you have finished working with the jig saw.