Hole saw

A method of assembling a pilot drill containing a left hand threaded mandrel into a hole saw to enable a plug of material to be removed from an interior of said hole saw, comprising the steps of:

• inserting a shank end of said left hand threaded mandrel through an open cutting end of said hole saw;
• threading said mandrel into complimentary left hand threads formed in a base of said hole saw;
• tightening said mandrel against said base end of said hole saw, a flange formed by said mandrel between said pilot drill and said shank end seats against said base of said hole saw;
• and
• disengaging said mandrel from said base of said hole saw and threading said mandrel out of said base, thereby subsequently removing said plug of previously cut material jammed into said interior of said hole saw therefrom.

A hole-saw apparatus comprising:

• an open-ended substantially circular hole-saw body forming an open cutting end having a plurality of teeth for cutting in a first direction of rotation and a base end, said body further forming walls between said base end and said open cutting end forming an interior therein, said base end defining an axially aligned aperture defining internal threads therethrough advancing in a second direction of rotation opposite to said first direction and
• a mandrel defining first and second ends adapted to be inserted through said open-ended circular body, said mandrel forming a pilot drill at said first which transitions into a flange and a shank portion at said second end and an elongated externally threaded portion, intermediate said flange and said shank portion, said elongated threaded portion being threaded in the same size and direction as said axially aligned aperture and threaded into said threaded axially aligned hole in said base end of said open-ended body such that said flange of said mandrel is tightened against said base end of said circular hole-saw by rotation of said mandrel in said first direction of rotation and is driven away from said base end by rotation of said mandrel in said second direction to remove a plug of material jammed between said flange and said walls forming said interior of said hole-saw after said hole is cut in said material.