How to Make Perfect Box Joints

With the board attached to your table saw's miter gauge, the next step will be to cut a notch in the board to accommodate a spacer block.

If the strip that you cut in step 1 was 1/2" wide by 1/2" high, then you'll need to adjust the height of your dado blade to 1/2" above the top of the table saw. Then, turn on the motor and slide the miter gauge forward, guiding the backer board all the way through the blade, cutting a 1/2" x 1/2" notch in the board. Slide the gauge back toward your body (clearing the blade again) and then turn off the saw.