Get double duty from a combination square
Drill a 1⁄16 " hole through the center of the guide slot in the blade at the 1" mark as shown. Insert a pencil tip or a scribe through the hole for marking. To figure the distance from the mark to the edge of the stock, remember to subtract 1" from the distance shown on the scale where it intersects the crosspiece. Hold the pencil and square steady as you mark.
—R.L. Watkins, Naches, Wash.