Small Hole Gages are tools that are unique to the process of accurately measuring holes. It is being inserted into the bore and adjusted by rotating the knurled knob at the base until light pressure is felt when the gauge is slightly moved in the bore. The gauge is then removed and measured with a caliper or micrometer.
To accurately detect the maximal distance between the two halves of the gauge head, move the head of the gauge around while making the measurement to ensure you get the maximal reading. Grasp the gauge near the head to aid in your maneuvering of the gauge while adjusting the micrometer so it just stops the gauge's motion at one spot only. A bit of practice will quickly give you the idea.
Ideal for accurately measuring small holes, slots, grooves, and recesses
Precision Ground Radius on each gauge provides two-point contact for maximum accuracy
Used for general work
More accurate measurements
4 sizes of gauges: 1/8"-1/5",1/5"-3/10",3/10"-2/5",2/5"-1/2"
Hardened-ball measuring surface with two-point contact
Smooth, sensitive adjustment
Adjustment of the gage beyond their range is restricted by a safety stop that prevents breakage