An embodiment of a spade bit has straight grooves at a lead angle of 4 to
8 degrees placed on flat edges of the spade bit. In an alternative
embodiment, a spade bit has two steps of straight grooves at a lead angle
of 4 to 8 degrees placed on flat edges of the spade bit. In other
alternative embodiments, a spade bit has tapered flat edge which have
straight grooves at a lead angle of 4 to 8 degrees placed thereon. The
straight grooves on the flat edges of the spade bits allow the spade bit
to pull itself through the workpiece with a minimal amount of
penetration. The flat edges of the spade bit may also have cutting
surfaces for cleaning the hole and permitting the easy removal of the
spade bit from the hole after drilling.