There are many commercial saddle squares available that allow you to mark three adjacent faces of a workpiece without moving the square, but they’re rather expensive. What I wanted was a three-sided saddle square that wouldn’t break the bank. What I came up with is the simple square you see above and in the drawing below. This saddle square is made from four plywood parts and some common hardware items. The fixed jaw has two guides glued in notches at the top corners. I cut the notches at the band saw. The rear, sliding jaw gets a threaded insert installed as shown above. A cap screw and small spring hold the sliding jaw in position. Depending on the spring’s tension, this square will adjust to accommodate workpieces from 1/4" to 1 1/4" thick.