Manually operated chuck

A manually operated chuck for machine tools for machining of rotationally symmetrical workpieces involving cutting, the chuck comprising:

• a base body adapted to be attached to the machine tool, clamping jaws each held in a radially movable arrangement on said base body (4) for securing the workpiece and in which an opening is disposed running at right angles to a longitudinal axis of said base body,
• a threaded spindle mounted in the opening in a movable arrangement, wherein the threaded spindle can be accessed from the outside in order to change the position thereof,
• a wedge bar disposed in the base body in an area of said threaded spindle, the wedge bar being connected to said threaded spindle and one of said clamping jaws in a shape-locking arrangement,
• a driving ring mounted in said base body in a rotating arrangement, such that the driving ring is connected in a shape-locking arrangement to said threaded spindle and to a further wedge bar allocated to two further clamping jaws, and
• with play between the threaded spindle and the driving ring and/or the threaded spindle and one of the wedge bars and/or between the driving ring and the corresponding wedge bars (9) of said clamping jaws,
• wherein
• at least one centring device is supported on said base body (4) and movable radially and provided laterally offset to one or more of said clamping jaws (6, 7 or 8),
• wherein each centring device exerts a radially vectored force acting directly on the workpiece to be clamped, which is adjustable, by means of which the play is compensated,
• and the centring devices are adapted to be actuated jointly synchronously or independently from one another and/or independently from said clamping jaws.