Buy an assortment of machine keys—the metal rectangular blocks used to lock pulleys and gears on drive shafts—and use them to adjust table saw and router cuts precisely. Since machine keys come in exact fractional dimensions—1/16, 1/8, 1/4, 3/8, 1/2 in. and higher—they take the guesswork out of setting the table saw blade-to-fence distance. Machine keys also work well for adjusting the router bit height above the router base or table—just set the right-sized key on the router table or base, hold a straightedge on the key so it hangs over the bit, and raise the bit till it touches the straightedge. Machine keys cost $6 for an assortment at an auto parts or farm supply store.
P.S. Be sure your saw or router is unplugged when you’re setting up the cut!