Sine Plates

Quick Answer

A sine plate is a precision workholding and angle-setting device that uses a hardened, ground flat plate mounted on a precision hinge, elevated to a calculated angle by placing a stack of gage blocks under one end. Because the angle is set trigonometrically — the sine of the desired angle multiplied by the sine plate length equals the required gage block height — sine plates provide extremely accurate angular positioning for surface grinding, inspection, and precision machining of angled surfaces.