Location in JIG

One of the most significant requirements of a successful jig design is that while workpiece is machined and eliminated from the jig, the operator must be able to put another workpiece rapidly into jig, clamp it and machine it to the dimensions with given tolerance.

Principles of Location

1. Relate the location to dimensional requirements of workpiece.

2. It is preferable to use most precise machined surface for location. If there is variation on the chosen surface, the new surface will also contain variations and one can get workpiece with defects. If most accurate machined surface is not available, select better machined surface out of available machined surfaces. Figure depicts how to select accurate surface for location.

3. Prevent motion along and around X, Y, Z.

4. Location system should provide easy and quick loading and unloading of workpiece with minimum motions.

5. Avoid redundant locators. Redundant locator means more locators are provided than needed for support. If three supports are adequate and one places four supports also, then fourth support is redundant. There are stool stands on four legs. But stool can also comfortably stand on three legs. In this case fourth leg is redundant one.

6. Prevent wrong loading of workpiece by fool-proofing.