A part of this small size requires a minimum nominal clearance of .0005 inch to enter the nest which gives a minimum nest diameter of 1.4375+.0005= 1.4378 (0) inches. To this is applied a manufacturing tolerance (machining tolerance, " toolmaker's tolerance") of .001 inch resulting in the nest diameter 1.438 inches. If the nest is at its maximum of 1.439
1.439 it provides a clearance of .0025 inch against a part of minimum diameter 1.4365 inches. These relationships are shown in Fig. 16-4. The selection of the fixture dimension and tolerances is in accordance with sound economic principles.