Buying Hole Saws
For as little as $15, you can buy a set of carbon-steel hole saws for drilling wood. For about $45, you can buy a set of bimetal hole saws that will cut wood and metal and last a lot longer. You can also buy specialty hole saws coated with Carborundum or diamond grit to cut hard materials like tile and stone. These saws, however, won't cut wood. Most hole saws mount to a separate centering guide called an arbor. Others are one piece. Better arbors (about $12) have two pins that slide into holes in the bottom of the hole saw to lock the saw in place. Match the arbor to your saw and check that it will fit in your drill. Some arbors require a 1/2-in. chuck and drill.