Wooden shims are useful for levelling a floorboard, hanging a door or any project where you need a small wedge. If you're planning to shim something outdoors or in contact with a damp surface such as a floor joist against a foundation block, use treated lumber or a durable wood such as oak. You can cut shims by feeding a block of wood by hand into a table saw blade but a homemade shim-cutting jig does the aligning for you. If you want shims wider than you can cut from a 1-inch board, make the jig out of 2-inch thick wood instead.
Saw a 1-by-6-inch board 8 inches long. Cut a narrow 7-inch-long wedge-shaped notch out of one side of the board, using a table saw, hand saw or jigsaw. The widest part of the wedge will be the maximum thickness of your shims.
Saw another 1-by-6-inch board 8 inches long. Place it flat on top of the other board and drill pilot holes for four 1 1/4-inch screws spaced near the corners. Spread carpenter's glue on the underside and screw it to the other board. When held flat against a table saw's bed, the covered notch will hold a scrap piece of 1-inch-thick board at a slight angle to the blade, allowing you to saw a shim from its edge.
Cut a 2-by-4-inch board 4 inches long and sand it smooth for a handle so you can push the jig beside the blade. Drill pilot holes for two 2 1/2 inch screws running up from the bottom of the 6-inch boards into the block. Sink the heads so they won't rub against the table. Glue and screw the handle in place.
Set the jig on the saw's table and insert the end of a scrap 1-inch board into the notch. Set the fence so the blade will saw the board 1/16 inch beyond the edge of the jig. Start the saw and push the scrap board and the jig toward the blade, slicing off a small wedge-shaped shim that remains underneath the jig.
Keep your fingers clear of the table saw blade at all times. Use the jig cautiously and be aware of the position of the blade as you work. Cut shims only from a scrap board long enough so you can hold it with your fingers safely away from the blade.