The threaded end of this collet is seperate from the solid body. When closing the draw bar, the threaded end pulls the internal tapered rod, expanding the internal collet. The long rod, which is a tight fit in the wrist pin holes, is used to zero the piston for the final machining of the crown & OD. IT IS VERY IMPORTANT FOR THE WRIST PIN HOLE TO BE SQUARE TO THE OD OF THE PISTON!! THE WRIST PIN SHOULD ALSO BE CENTERED AS DESCRIBED IN THE PREVIOUS PHOTO! Final fitting of the piston to the liner is done with this collet. The taper used, for a distance of .1000 at the piston crown, is also cut at this time using the lathe's compound. The compound has been pre-set with a taper master for this VERY CRITICAL OPERATION! There will be no way to check the piston's top taper for correctness after completing the cut, except with a good quality comparator.
