What is a spade bit?
A spade bit is a type of wood boring drill bit that was invented in 1968 by the Irwin tools company. It is flat, with two sharp lips able to rapidly scoop out material from a bore hole.
These lips can sometimes have spurs at the edges, which cut around the edge of the bore hole to make a cleaner cut.
Spade bits have a reputation for cutting rough, scrappy holes, and for causing splintering when the bit enters and leaves a wooden workpiece. This is known as tear out.
Some spade bits have been designed with holes in the body of the bit so that they can pull electrical cables back through bore holes in walls (you might be trying to connect an aerial to a TV, for example). Their shanks are long enough for you to tie the cable to the bit using string or a piece of thin wire.
For more information on this process, see:
The spade bit's name comes from its shape. It is also referred to as a paddle bit or a flat bit.