A workpiece holder 1 includes a holder head 11 and a holder body 12. The holder head 11 includes a chuck unit 13 for holding a workpiece W, a support pedestal 111 for supporting the chuck unit 13, and a hook 113 provided on a distal end portion of an arm 112 extending from the support pedestal 111. The holder body 12 includes a cylindrical body portion 121, a retained portion 123 that is arranged inside the body portion 121 and rotated around the cylinder axis J1 to be in either a retained state in which the retained portion 123 is retained by the hook 113 on the ?Z direction side or in the released state in which retaining by the hook 113 is released, and a disk spring 126 for biasing the retained portion 123 in the ?Z direction.

Methods, devices, and systems for positioning workpieces for processing. In one aspect, a clamping device includes two clamping elements and a servo drive provided for the clamping elements. The servo drive is operable to first move at least one of the clamping elements toward the other of the clamping elements such that the clamping elements are transferred into a clamping start position in which the clamping elements are positioned on opposite sides of a workpiece arranged therebetween and in which the clamping elements do not apply a force to the workpiece or apply a force to the workpiece that is smaller than a clamping force, and subsequently urge the clamping elements toward one another from the clamping start position to an operational state, in which the clamping elements apply the clamping force to the workpiece.

A workpiece holder 1 includes a holder head 11 and a holder body 12. The holder head 11 includes a chuck unit 13 for holding a workpiece W, a support pedestal 111 for supporting the chuck unit 13, and a hook 113 provided on a distal end portion of an arm 112 extending from the support pedestal 111. The holder body 12 includes a cylindrical body portion 121, a retained portion 123 that is arranged inside the body portion 121 and rotated around the cylinder axis J1 to be in either a retained state in which the retained portion 123 is retained by the hook 113 on the Z direction side or in the released state in which retaining by the hook 113 is released, and a disk spring 126 for biasing the retained portion 123 in the Z direction.

A bit holder for a rotary power tool includes a body rotatable about a central axis, the body including a bit aperture configured to receive a tool bit, a collar surrounding the body, the collar rotatable with respect to the body about the central axis, the collar including a first cam profile and a second cam profile, and a plurality of jaws rotatably coupled to the body such that each jaw of the plurality of jaws is rotatable about a jaw axis, each jaw of the plurality of jaws including a first cam arm configured to engage and move along the first cam profile and a second cam arm configured to engage and move along the second cam profile.