Adjustable quick change jaw apparatus

An adjustable chuck jaw apparatus for attachment to a master jaw in the front face of a rotary chuck for allowing a machinist to quickly change the chuck jaws from one diameter to another, comprising:

• a generally rectangular jaw body adapted to be connected to a master jaw in a front face of a rotary chuck to extend radially outward from a central rotational axis of the chuck;
• a jaw member having a longitudinally extending arcuate threaded segment along one side and a gripping portion extending perpendicularly outward to grip a workpiece;
• an elongate rotatable shaft mounted in said jaw body having an arcuate threaded segment on its outer periphery sized to become engaged with said arcuate threaded segment of said jaw member when rotated to an engaged position and to become disengaged therefrom when rotated to a disengaged position, and a recessed portion in its outer periphery in opposed relation to its said arcuate threaded segment;
• spring biased locking pin means slidably mounted in said jaw body having a sliding element selectively engaging said shaft recessed portion to prevent rotation thereof in a locked position and to become disengaged therefrom to allow rotation thereof in an unlocked position, said locking pin means being normally spring biased to said locked position;
• upon manually depressing said locking pin means and rotating said shaft said sliding element is free to slide relative to said shaft as it rotates to engage and disengage said arcuate threaded segment of said shaft with said arcuate threaded segment of said jaw member, and upon releasing said locking pin means, said sliding element engages said recessed portion when said threaded segments are engaged to prevent rotation of said shaft and maintain the engagement of said threaded segments;
• wherein
• when said locking pin means is moved to its said unlocked position, said jaw member is incrementally moved longitudinally along said jaw body with respect to the central rotational axis of the chuck by rotation of said shaft;
• and
• upon depressing said locking pin means said shaft may be rotated to said disengaged position and said jaw member may be manually removed from said jaw body or moved thereon relative to said workpiece and accurately adjusted to grip said workpiece, and upon releasing said locking pin means said sliding element engages said shaft recessed portion to prevent shaft rotation and said jaw member is maintained in said adjusted position.