Patent ID: 7556459

Claim:
A hole saw comprising: an arbor; a cup shaped cutting member coupled with said arbor, said cup shaped cutting member having a skirt with teeth at its free end; a drill bit coupled with said arbor or cup shaped cutting member for forming a starter hole in a workpiece, said drill bit including a first cutting tip having a first cutting edge including an inner and outer cutting edge portion, said first cutting tip defining a first diameter, and a second cutting edge defining a second diameter, said second diameter being larger than said first diameter, said second cutting edge axially spaced from first cutting edge so that said first cutting edge forms a bore of said first diameter in the workpiece prior to said second cutting edge entering said workpiece, said second cutting edge being angled from horizontal with respect to a longitudinal axis from 22° to 27°, and said second diameter defining a diameter of a twist drill having a substantially constant diameter cutting said workpiece at a rotational speed between 300 to 1200 RPM.