The RV516 is among the fastest and most accurate valve grinding machines now available on the market, thanks to its technical solutions. The centerless grinding system - that makes the valve rotate on its stem - ensures the perfect concentricity between the head and the stem (within 0.01 mm) and can operate a wide range of valve stem diameters (from 4 up to 16 mm) without the need for replacing any collet or spindle.The valve drive system is performed by three motorized rollers. The top roller is tilted to automatically drive the valve on an adjustable control switch. This guarantees to accurately control each valve's length and to avoid to manually feed the valve towards the grinding wheel.