A tool bit assembly includes a tool bit having a shaft with a first working region disposed at a first end of the shaft and a first reduced diameter portion proximate the working region and disposed between a first shoulder and a second shoulder. A floating sleeve has a rear portion with a pair of opposed window openings, a front portion supporting a magnet, and a pair of balls, with each ball disposed in one of the window openings. The floating sleeve is receivable over the tool bit with the magnet proximate the first working regions and the balls received in the first reduced diameter portion to allow the floating sleeve to move between a first position in which the balls abut the first shoulder and a second position in which the balls abut the second shoulder.

A tool bit assembly includes a tool bit having a shaft with a first working region disposed at a first end of the shaft and a first reduced diameter portion proximate the working region and disposed between a first shoulder and a second shoulder. A floating sleeve has a rear portion with a pair of opposed window openings, a front portion supporting a magnet, and a pair of balls, with each ball disposed in one of the window openings. The floating sleeve is receivable over the tool bit with the magnet proximate the first working regions and the balls received in the first reduced diameter portion to allow the floating sleeve to move between a first position in which the balls abut the first shoulder and a second position in which the balls abut the second shoulder.

An axially elongate dental machining portion includes a machining region machinable by a dental machining device, and a fixing region for fixing the axially elongate dental machining portion to a holder of the dental machining device. In the fixing region is a fixing projection oriented transversely relative to a longitudinal axis. In a condition of the machining portion being mounted in the holder, the fixing projection bears against a holding nose positioned in complementary relationship on the holder. The machining region has a machinable surface which has a maximum spacing relative to the longitudinal axis, measured normal to the longitudinal axis, and the fixing projection has a maximum spacing relative to the longitudinal axis, measured normal relative to the longitudinal axis, that is greater than the maximum spacing of the machinable surface relative to the longitudinal axis.

A tool bit assembly includes a tool bit having a shaft with a first working region disposed at a first end of the shaft and a first reduced diameter portion proximate the working region and disposed between a first shoulder and a second shoulder. A floating sleeve has a rear portion with a pair of opposed window openings, a front portion supporting a magnet, and a pair of balls, with each ball disposed in one of the window openings. The floating sleeve is receivable over the tool bit with the magnet proximate the first working regions and the balls received in the first reduced diameter portion to allow the floating sleeve to move between a first position in which the balls abut the first shoulder and a second position in which the balls abut the second shoulder.