Patent ID: 7896589

Claim:
A drill machine comprising: a housing; a motor coupled to said housing; an arbor defining a bore and coupled to said motor for rotation with said motor; a driving device coupled to said arbor and extending into said bore; and a cutter including a shank portion and a cutting portion with said shank portion having a central axis and extending along said central axis between a first end and a second end and with said cutting portion extending from said first end; said shank portion defining an entry channel extending from said second end for guiding said driving device of said arbor during insertion of said shank portion into said arbor and a retaining channel extending from said entry channel and terminating at a spherical surface for selectively retaining said driving device of said arbor, wherein said shank portion is cylindrical and has a constant diameter between said first end and said second end; and each of said entry and retaining channels having a trough portion extending toward said central axis with said trough portions of each of said entry and retaining channels having a common configuration for slideably receiving said driving device; wherein said spherical surface of said retaining channel extends outwardly relative to said central axis from said trough portion of said retaining channel for engaging said driving device to transmit rotation from said arbor to said cutter as said arbor rotates.