Cutting box joints without a dado blade

(continued from mirror stand)

I box joined the corners for this bracket using my screw advance box joint jig, of course.

Here's my pieces for the bracket in the jig The bracket has four joints, and I'm cutting one side of each of the four joints all at once, so I have four pieces stacked in the jig.

I have gotten into the habit of not bothering with changing to a dado blade when I make box joints. Too much trouble to go through. Instead of using a 1/4" dado stack, I just make three cuts with a regular blade to open up a 1/4" wide slot. I found I can push the sled much faster with just a regular blade, so it doesn't take much longer to make the three cuts it would to make one with a dado blade.

I'm using the 48 tooth gear against the 12 tooth gear. This gives me 4 turns of the 16 TPI shaft per crank turn. Thus, 1/4" advance per crank turn. I put little bits of electrical tape on the crank to mark the crank angles at which I need to make cuts.

The first cut is with the crank handle by the gears at right, then I turn it counterclockwise until the first tape is to the right by the other gears, make a cut, and then turn it to the third crank position (shown in previous picture). After that cut, I turn the crank one and one third turns counterclockwise so that the handle is to the right, next to the gears, and repeat.

As I often do, I made a video of the procedure. I wanted to capture some close up video of making the cuts, so I clamped a small tripod to the jig and videoed it from that perspective. It looks like the blade moves and the jig is stopped. The only confusing bit is that the shadows keep changing as I'm sliding the jig. The box joint procedure starts at 3:40 into the video.

Here's my pieces cut. I marked the right side of all pieces with an X for the first cut, and a Y when I cut the mating parts. The mating parts are offset by 1/4" from the first, so everything lines up. Offsetting by 1/4" is easy - all I had to do was turn the crank by one turn!

C-bracket assembled. I also glued some blocks of wood in place to keep the stand's post aligned so it's recessed by about 3 cm from the edge of the mirror.

More about this screw advance box joint jig

Next: Putting together the mirror stand