Sometimes, when working in very old homes I need to replace an old lockset where the hole is too small for a new style lockset. I used to go through all the trouble of filing out the old hole to fit the new lockset, what a pain! I’ve discovered an easy solution using two hole saws, one the original size, and the other the new size hole you want to drill. If you’ve ever used one you’ll know there’s a pilot bit down through the center, usually held in place with a set screw. Simply remove the bits from both hole saws, then using one of the bits, place the original hole size unit on the pointed end and tighten the set screw, then slide the whole thing inside the bigger unit and tighten the set screw there as well. Now chuck the whole thing into your drill and away you go.