1.A working gauge answers/enters the components but the inspection gauge doesn’t answer:
Customer is advised to buy two gauges, one for checking production items and second one for quality control and inspection. It is essential that the gauge which is used on shop floor, must have effective diameter at MAXIMUM size, and the gauge used for quality control should have effective diameter at BASIC size. This will prevent above error. This should be specified while ordering so that you get gauges marked separately.
2. Go-gauge doesn’t enter but the no-go answers freely
This occurs if the major diameter of nut (internal thread) or minor diameter of bolt (external thread) is not maintained properly. The major diameter of the go plug and minor diameter of the go ring gauge is sharp and hence obstructs with the corresponding diameter on the component. The operator many times wrongly takes higher cut without correcting the tool sharpness. No-go plug starts entering and component gets rejected as effective diameter has become oversized.
3.The no-go major diameter / minor diameter being more truncated than the go gauge, enters the component.
The go-gauge controls all the thread parameters and will not enter if any of these are incorrect. However No-go plug gauge controls effective diameter only, as major diameter of not-go plug is truncated.
4. All the parameters like major diameter, minor diameter, effective diameter, pitch and flank angle must be controlled within specified tolerances.
5. For full form gauges like BSW, BSF, BSPT, BSP and BA two additional parameters viz. Radius at major diameter and radius at minor diameter need to be controlled.