Drill bit: Difference between revisions

Installer bits are a type of twist drill bit for use with a hand-portable power tool. They are also  known as '''bell-hanger''' bits or '''fishing''' bits. The key distinguishing feature of an installer bit is a transverse hole drilled through the web of the bit near the tip. Once the bit has penetrated a wall, a wire can be threaded through this transverse hole, and the bit pulled back through the drilled hole. The wire can then be used to pull a cable or pipe back through the wall. This is especially helpful where the wall has a large cavity, where threading a fishtape could be difficult. Some installer bits have a transverse hole drilled at the shank end as well. Once a hole has been drilled, the wire can be threaded through the shank end, the bit removed from the chuck, and all pulled forward through the drilled hole. Sinclair Smith of Brooklyn, New York was issued US patent 597750 for this invention on [[25 January]] [[1898]].