Least count of micrometer screw gauge
Least count of screw gauge is 0.01 mm.
The least count of any measuring instrument is the smallest change in the measured quantity that can be resolved on its scale. The equation to find out least count is,
L.C. = Minimum Main scale division / Total circular scale divisions
The diagram shows a metric micrometer and nomenclature of its parts.
0.5 mm is the min main scale division value and a circular scale is divided into 50 lines. We can now get the answer by dividing the values as per the above formula.
Least count of screw gauge = 0.5 / 50 = 0.01 mm
- Before taking the reading on micrometer check if it has any positive or negative zero error. If it does have then re-calibrate it.
- Avoid directly rotating circular scale. Instead, use the ratchet to get fine measurements.
- The part should be free from burr.