A chuck for a high precision machine tool and method for making a multi-cavity die or mould

A chuck for a machine tool having a rotation spindle with a main axis of rotation, in particular a lathe, the chuck being arranged for positioning an object, such as a work piece, at a relevant position with respect to the main axis of rotation, the chuck being arranged such that the chuck together with the object positioned on it has a principal axis of inertia that can be arranged to coincide with the main axis of rotation, the chuck comprising:

• a base plate comprising mounting means for mounting the chuck to the spindle;
• a first rotatable plate eccentrically mounted on the base plate with respect to the main axis of rotation and having a first rotation axis running in parallel to the main axis of rotation such that the first rotational axis is shifted with respect to the main axis of rotation of the spindle;
• balancing means arranged for balancing the centre of gravity of the chuck together with the object positioned on it with respect to the main axis of rotation such that the principal axis of inertia of the chuck together with the object substantially coincides with the main axis of rotation (19) of the spindle (14);
• a holding mechanism arranged for securing the first rotatable plate to the base plate;
• and
• an actuating mechanism arranged for angularly displacing the first rotatable plate around the first rotation axis over a first angle of rotation such the position of the object with respect to the main axis of rotation can be altered;
• wherein the chuck comprises a second rotatable plate arranged for receiving the object, the second rotatable plate being eccentrically mounted on the first rotatable plate with respect to the first rotational axis and having a second rotation axis running in parallel to the main axis of rotation and the first axis of rotation such that the second rotation axis is shifted with respect to the first rotation axis, and being secured on the first plate by means of the holding mechanism;
• and wherein the actuating mechanism is arranged for angularly displacing the second rotatable plate around the second rotation axis over a second angle of rotation such that the position of the object with respect to the main axis of rotation can be altered.