Chuck assembly and collet

A chuck assembly comprising:

• a collet holder having an external thread and an internal bore which tapers rearwardly from a forward face;
• a collet mounted within the bore of said collet holder, said collet including:
• a radially resilient body with a tapered outer surface engaging the bore of said collet holder and a tool-receiving bore extending axially therethrough said body having an aperture extending radially from the outer surface into said bore;
• a tool-securing pin having a head portion at one end thereof, and a tool-securing surface toward the other end thereof;
• means for mounting said pin within the aperture while allowing a limited radial movement of the pin, said means including:
• a shoulder within the aperture;
• an undercut on the pin mediate of the ends thereof, said undercut extending a length in the direction of the ends;
• and
• a compressible spring member mounted on the aperture shoulder and around the pin undercut, said spring having a diameter greater than that of the pin undercut and less than the pin outside of the undercut and having a thickness less than the length of the undercut, so that said spring allows the pin to move radially along the length of the undercut;
• and
• means for urging the collet into the collet holder bore to compress the body around the tool, said means including an internal thread adapted to mate with the external thread on the collet.