Clamping assembly of a knockout punch

An assembly comprising:

• a draw stud formed as an elongated cylinder having first and second opposite ends, a conventional thread formed on said first end of said draw stud and a plurality of alternating grooves and lands formed on the second end of said draw stud, said grooves and lands being at least semi-annular, a portion of said draw stud between said ends being unthreaded;
• a first jaw having an outer surface and an inner surface, said inner surface of said first jaw having a plurality of alternating semi-annular grooves and lands formed thereon, a second jaw having an outer surface and an inner surface, said inner surface of said second jaw having a plurality of alternating semi-annular grooves and lands formed thereon, said jaws being pivotable relative to each other around a pivot;
• a spring provided between said first and second jaws, said spring biasing said jaws into a closed position in which said jaws are clamped onto the draw stud and the alternating grooves and lands formed on the first jaw mesh with said alternating grooves and lands formed on the draw stud and the alternating grooves and lands formed on the second jaw mesh with the alternating grooves and lands formed on the draw stud;
• a die mounted on said draw stud;
• and
• a punch mounted on said draw stud.