Abstract: An improved dumbbell exercise apparatus includes at least a pair of novel bullet-pocket configured weight plate members to be mounted in spaced end-wise relationship on a dumbbell bar, wherein each weight plate member is configured to include at least a pair of cylindrical pocket-like openings extending axially through the thickness dimension of the weight plates, respectively, in parallel and axially offset extension to each other, and at least a singular bullet-weight cylinder of conforming cylindrical dimension to the radius of an aligned singular cylindrical pocket opening in the weight plate, is selectively axially inserted into an aligned cylindrical pocket opening, in order to add or adjust weight to the weight plate, and novel locking means are provided to mount on the weight plate to prevent dislodging of the weight cylinder from the cylindrical opening during use of the dumbbell exercise apparatus.

Abstract: An improved dual blade boring tool having a solid surround housing portion in which a pair of parallel spaced transverse channel openings extend perpendicular to the longitudinal axis of the rotatable tool, a pair of dual cutter insert members are mounted in the channel openings, respectively, and are moved in opposite directions to each other responsive to rack and pinion movements of a rotatable cylindrical shaped cam member having at least a rack portion and being meshed to engage pinion portions provided on each of the dual insert members, whereby the rotation of the rack portion of the cam member converts to reciprocating movement of each of the meshed insert members to move oppositely disposed insert members in opposite and corresponding linear directions with respect to the surround housing of the boring tool.

Abstract: An improved dumbbell exercise apparatus includes at least a pair of novel bullet-pocket configured weight plate members to be mounted in spaced end-wise relationship on a dumbbell bar, wherein each weight plate member is configured to include at least a pair of cylindrical pocket-like openings extending axially through the thickness dimension of the weight plates, respectively, in parallel and axially offset extension to each other, and at least a singular bullet-weight cylinder of conforming cylindrical dimension to the radius of an aligned singular cylindrical pocket opening in the weight plate, is selectively axially inserted into an aligned cylindrical pocket opening, in order to add or adjust weight to the weight plate, and novel locking means are provided to mount on the weight plate to prevent dislodging of the weight cylinder from the cylindrical opening during use of the dumbbell exercise apparatus.

Abstract: An improved dual blade boring tool having a solid surround housing portion in which a pair of parallel spaced transverse channel openings extend perpendicular to the longitudinal axis of the rotatable tool, a pair of dual cutter insert members are mounted in the channel openings, respectively, and are moved in opposite directions to each other responsive to rack and pinion movements of a rotatable cylindrical shaped cam member having at least a rack portion and being meshed to engage pinion portions provided on each of the dual insert members, whereby the rotation of the rack portion of the cam member converts to reciprocating movement of each of the meshed insert members to move oppositely disposed insert members in opposite and corresponding linear directions with respect to the surround housing of the boring tool.