The Rottler SG10XY spindle is mounted on a sphere which allows the UNIPILOT to automatically center with the valve guide centerline while the Workhead is floating on air cushions. Once air floating stops and the Workhead clamps, the UNIPILOT and valve guide centerline are maintained while cutting the valve seat. Spherical Pneumatic Automatic Alignment System built into the Spindle for fast location of the pilot into the Valve Guide and Accurate Centering (Patent Pending) Air Float Work Head on Intermediate Base Plate Heavy Duty Spindle - Diameter 3.150” (80mm) Hardened and Ground with 8” (200mm) of vertical travel. Rottler Automatic Tightening and Quick Release Spindle Lock Nut System for One Hand Operation for fitting and removing tooling to and from the spindle – never comes loose!