Plug ejecting hole saw with interchangeable saw cups having different size attachment bores

An arbor holder for releasable attachment to a hole saw cup selected from first and second pluralities of hole saw cups of the type having a front annular cutting surface, a cylindrical body terminated at a rear end thereof by a rear transversely disposed circular base wall having through its thickness dimension a non-circular attachment bore concentric with said first annular cutting surface and said body, said attachment bore of said first plurality of hole saw cups having a first diameter, and said attachment bore of said second plurality of hole saw cups having a second diameter larger than said first diameter, said arbor holder comprising;

• a. a generally cylindrically-shaped collar having therethrough a longitudinally disposed bore,
• b. a generally cylindrically-shaped body longitudinally slidably held within said bore of said collar, said body having disposed longitudinally therethrough a coaxial bore internally threaded for receiving an externally threaded arbor and a nose-piece provided with a first, front nose-piece boss which protrudes forward from said collar, said front nose-piece boss having a non-circular transverse cross sectional shape insertable into said first smaller diameter attachment bore of said first plurality of hole saw cups, and a second, rear nose-piece boss of larger diameter rearward of said front nose-piece boss, said second, rear nose-piece boss being insertable into a said second, larger diameter attachment bore of said second plurality of hole saw cups, each of said front and rear nose-piece bosses having formed therein at least a first transversely disposed groove having an entrance opening for rotatably receiving in a first forward direction a first peripheral segment of a peripheral edge wall of a small saw cup attachment bore and a large saw cup attachment bore, respectively, and at least a first longitudinal groove disposed longitudinally within said body, said longitudinal groove longitudinally slidably holding a locking tab lug which is resiliently biased forward in said groove by spring means to thereby block with a first, front locking tab an entrance opening to said first front nose-piece transverse groove, and with a second, rear locking tab an entrance opening to said first rear nose-piece transverse groove, said locking lug being resiliently movable rearwards to unblock said openings of said first front and rear transverse grooves to thereby unblock said transverse grooves,
• c. means for limiting rearward movement of said cylindrical body relative to said collar, and
• d. means for limiting forward movement of said cylindrical body relative to said collar.