A dial caliper takes precise inside and outside measurements, but the depth probe on the end can also help you set exact blade and bit heights. The key is to lock the caliper vertically in a jig like I made here. The base is 4" square, and the upright is 3-1⁄2" x 5" with a 5/8" x 2-1⁄2" notch cut into one edge. I cut a 5/8"-deep kerf into the edge above the notch with 1/8"-kerf saw blade; this slot fits a standard caliper perfectly. I stepped to the band saw to cut a centered slit across the top of the upright, 2" deep. By threading a bolt and wingnut across this thin kerf in the upright, the bolt applies just enough pressure to hold the caliper in place. To set bit or blade height, I lower the probe to the table and zero out the gauge, then raise it to the cutter height I want. Now crank up the cutter until it touches the probe. It’s a handy jig to have around.