Arbor apparatus for rotary tools

An arbor apparatus for mounting an attachment for a rotary drive tool, said attachment having a drive opening, and said arbor apparatus comprising:

• (a) a mandrel comprising, in coaxial arrangement:
• a.1 a chuck stage, adapted for removable engagement with a chuck of a rotary drive tool;
• a.2 a threaded shaft stage adjoining the chuck stage, with the radius of the threaded shaft stage at the thread root being not less than the largest radial cross-sectional dimension of the chuck stage;
• a.3 a drive stage adjoining the threaded shaft stage and having a non-circular cross-section, with the smallest radial cross-sectional dimension of said drive stage being not less than the outer radius of the threaded shaft stage;
• and
• a.4 a non-circular locking plate adjoining the drive stage, and having an upper surface and a substantially planar lower surface, said lower surface being oriented toward the drive stage and being substantially perpendicular to the longitudinal axis of the mandrel;
• (b) a drive boss comprising:
• b.1 a main body section having an upper end and a lower end;
• b.2 a prismatic drive head projecting above the upper end of the main body section and having an upper surface, said drive head being of a cross-sectional shape adapted for mating engagement with the drive opening of the attachment;
• wherein:
• b.3 the drive boss has a central passage extending therethrough from the upper surface of the drive head to the lower end of the main body section;
• b.4 the central passage is geometrically configured to receive the drive stage of the mandrel in mating engagement therewith, such that rotation of the mandrel will induce rotation of the drive boss;
• b.5 the orientation of the central passage relative to the drive head is such that upon insertion of the drive stage into the passage, a portion of the locking plate will project over the upper surface of the drive head;
• and
• b.6 the upper end of the main body section of the drive boss defines a shoulder surface extending radially beyond the perimeter of the drive head, said shoulder surface being substantially planar and being substantially perpendicular to the longitudinal axis of the drive boss;
• and
• (c) a locking nut having a threaded bore engageable with the threaded shaft stage.