Abstract: A top jaw system for securing a top jaw in position above a chuck on a milling machine, lathe or the like is provided. The system generally includes a base jaw, top jaw, master jaw, and a conventional jaw nut. The base jaw includes a bottom portion and a portion and a wedge portion. The top jaw is removably attached to the wedge portion by a pin while the bottom portion is removably attached to the jaw nut by removable mounting bolts. The jaw nut is disposed within a channel of the master jaw. The top jaw can be quickly replaced by the removable of the pin.

Abstract: A top jaw system for securing a top jaw in position above a chuck on a milling machine, lathe or the like is provided. A protrusion extends upward from the chuck and is preferably attached to the chuck by rigid attachment to a jaw nut which is positioned in a common master jaw on the chuck. The protrusion has a pair of flat faces which extends upward and over the jaw nut to form acute angles with the jaw nut. A top jaw having a slot sized to receive the protrusion is placed over the protrusion. The top jaw has a pin aperture extending through the top jaw through the slot at a right angle to the protrusion when the top jaw is placed on the protrusion. When the top jaw is placed on the protrusion, an elongated pin having a pair of flat surfaces extending along its elongated axis is placed in the pin aperture. One of the flat faces of the protrusion is pushed into contact with one of the flat surfaces of the pin.