Rottler Valve Refacing Machines grind valves to minimum CONCEN for improved sealing and performance. VR Series ... VR12 Centerless Grinding; Honing. H85A CNC Vertical Honing; H85AX CNC Hole-to-Hole; H85AXY CNC Hole-to-Hole & Optional Block Roll Over; H87AXY CNC Heavy Duty Applications;