How to Make Perfect Box Joints

The procedure for making the first notch in the second, corresponding board is different than the procedure used to cut the first. If you cut the second board the same way as you cut the first, the edges of the board won't match up when you assemble the joint.

To align the second board, place the edge of the board against the table and the face against the jig's backer board (as before), but this time, slide the board to the right so that the top edge of the board just barely covers the notch in the jig. Notice in the picture above, that the board just barely covers up the notch, which is 1/2" away from the spacer block.

Clamp the board to the backer board and cut the first notch. This notch should be much like a rabbet, where the full width of the notch matches the edge of the board.

After completing this first notch, remove the clamp, slide the board to the right so that the first notch is positioned over the spacer block. Re-clamp the board to the jig and cut the second notch. Continue this procedure as before until all of the finger notches have been cut.