Octagonal box with 45° box joints
I had this idea of making a wagon deck with 45° corners, and box joining these corners with my box joint jig.
I stacked two 7 1/4" blades to get a thicker kerf, and worked out that the 31-tooth gear against the 12 tooth gear on my box joint jig gave the right fit for use with the kerf from those two blades.
I cut the boards at a 45° angle, using my old table saw. That way I could go back and cut miters while leaving the set-up on my main saw untouched.
The best way the boards would fit in the box joint jig at a 45° angle is like this. But that would require the blade to cut "out of" the grain. That orientation makes it difficult for the saw's teeth to grab the fibers, so saws work very poorly in that direction.
I made a board that fits into the box joint jig at a 45-degree angle. The board has a V-groove to fit on the top edge of the jig and a small notch in it at the right side for an F-clamp to pass through.
I used a strip of wood to brace the workpiece against sliding back in the jig.
So far, going clockwise around the box, I had cut all the second, or right hand side joints. None of the pieces were cut to final length yet, so if I screwed up, I could just cut the board shorter and re-cut the joint.
I'm using the sled "backwards" because this table saw tilts left, which would cause it to tilt into the sled in its normal left-side position. Putting the sled on the other side avoids that.
Then cutting the joints on the other end. This required re-aligning where I cut the fingers to make sure they meshed with the fingers I already cut. Normally, when making boxes, I always place the stock in the jig so that what will be the top edge of the workpiece is at the right edge of the jig. But with these 45° joints, I have to orient them bevel down, and that means the second joint in each piece had to be oriented with the top edge facing left.
I lined these up by taking one of my initial joints, placing it in the jig with the fingers down but the top facing left (bevel up), and lining up the blade so it would cut where a finger was. I used that as the first cut position and indexed the rest off of it.
Two of the joints in the mahogany were too messed up, so I made two new pieces to replace them, but then I messed up one of those. Rather than make yet another new piece, I decided one of my original messed up pieces was still salvageable.
I used my edge belt sander to clean up the box joints. Some of them had quite a bit of protrusion, so I flatted some on the bandsaw first.
Adding the 45° corners to the box doubled the number of joints I had to make, and at least tripled the work of making this box due to added complexity. It looks nice, but I'd recommend you think twice before making an octagonal box! In this instance, cutting corners didn't save me anything!
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