Need to drill a 1-in. hole through a concrete foundation? You can buy a 1-in. hammer drill bit with a 1/2-in. shank, but it won’t be long enough, and drill bit extensions aren’t designed to take abuse from a hammer drill. Even if you didn’t need an extension, the 1-in. bit likely exceeds the rated capacity of your hammer drill. As a rule, a heavy-duty 1/2-in. hammer drill is limited to a 3/4-in. bit. Even if you could find a stepped down shank that you could chuck into your drill, you’re better off renting a rotary hammer drill with the proper length bit. It’ll get the job done in a fraction of the time and with a lot less sweat.