Fig. (a) Workpiece with cylindrical pin

Fig. (b) Enlarged top view of diamond pin

• Let, consider a work piece with two drilled holes P and Q

• Here, P and Q holes are used for locating the workpiece by means of pins.

• The clearance is provided in pin and pin hole for accurate mounting of pin.

• If only p location is engaged with pin, then the job or work piece can rotate in either direction about the pin ‘P’

• If pin p and q both engaged. But because of clearance between hole and pin. Exact distance can not be obtain.

• Hence to obtain exact location of work piece the relief is provided on two sides of pin.

• The purpose of providing relief is, to allow variation in x-x and y-y direction.

• After providing the relief, the pink looks like diamond shape hence called diamond locator as shown in fig (b)