| So to solve this problem,
I replace the standard blade with a reverse-cutting blade, see photo. Unlike a
standard blade, the teeth on a reverse-cutting blade point down. So it produces
Another problem may be the distance covered by the stroke
of the blade. If it's too long, it will cut through the bottom skin of the door.
Although you can't change the stroke of the jig saw, you can shorten the blade
to keep it from cutting all the way through.
To do this, first set the base of the saw on the edge
of the door, see the drawing at right. With the blade extended as far down as
it will go, mark it just above the bottom skin. Next remove the blade and score
it at this mark with a file. Then secure it in a vise and cut it to length with
a hacksaw. Now you're ready to safely cut clean openings in a hollow-core door.