This is my screw advance box joint jig.
It can be used to make very fine box joints,
like this one, or like this one.
And, to precisely control the spacing,
it uses a threaded rod and interchangeable gears.
And the question I'm often asked is,
if I don't have a bandsaw,
how do I make these gears.
A popular substitute for a bandsaw is to use
a jigsaw, like this one.
But, the problem with that is, it's hard to see
where you're working and the blade is not that stable.
Even on an expensive one, the blade still flexes.
So, the thing to do is mount it upside down
and then add something to guide the blade
and that should make it suitable for gears.
Rather than having the saw poke through the plywood,
I figured a slot is better.
And I had to cut some extra holes here because
it protrudes a little bit here.
I could attach this saw by putting some drywall screw
right on the round edge of it,
but I also want something to cover this area
so I won't get debris falling in there.
So, I just made this thing here with a slot in it.
And I've got 2 screw holes right here
so, that mounts like so.
Now, I need to make a guide that holds the blade on top.
And, I figure just a piece of wood
supported like this, and with a slot in it right here,
should do the trick.
And a drop of oil is probably a good idea for the slot
just to make sure everything slides better.
And, now I just need to put this here,
and I need to fix that very rigidly.
So, I'm just gonna put it on with a couple of C-clamps.
I'm gonna put this scrap of plywood here, and
it's about the same thickness as this so I have
more support. I'm gonna use a print-out
of one of the gear templates from my
box joint jig plans.
I have to be careful to really hold the work piece
and not try to cut curves, otherwise it really jumps.
Cutting the spaces between the teeth can be
sped up a little bit by drilling some holes.
So, this gear still runs a little bit rough.
I can improve on that by sanding and by slightly
beveling the back edges so that it will better run
against this gear at a right angle.
The best tool for tweaking the gears is just to
tilt the table on a strip sander and then sand the teeth,
like this. If you don't have a strip sander,
just take a course piece of sand paper
wrap that around a piece of wood and
just go at the teeth, like this.
After sanding and a bit of tweaking,
I'm not getting any more binding on here.
I'm often asked what tools are need for a specific project
and my answer is always,
depends on your skills, because the more
resourceful and patient you are,
the fewer tools you really need.