Most grinding is done by abrasive wheels that rotate at high speed, or by power-driven cloth or paper belts coated with an abrasive. In precision grinding the same methods are used, but with extreme precision in the grinding process. Precision grinding allows tolerances in excess of 0.001” to 0.00001” to be achieved, but only if the proper machinery is used. What is the correct or proper machinery? The correct machinery needed for precision grinding must be constructed very accurately, with very heavy, rigid frames to assure permanency of alignment. Two other important factors in achieving precise tolerances are to accurately balance rotating parts to avoid vibration and to mount spindles in very accurate bearings. Controls are also provided to insure that all movements of machine components used to determine critical dimensions are made with accuracy.