Micrometer Screw Gauge, The screws in one rotation proceed through the same distance as the screws. Measurements are made of a precisely made joint screw with a pitch of 2 threads per millimeter, which means that the displacement obtained when one revolution is complete is 0.5mm. They are more accurate than Vernier calipers.
- A – Anvil
- B – Spindle Lock Nut
- C – U-frame
- D – Barrel ( Main scale )
- E – Thimble ( Circular scale )
- F – Ratchet Stop
The smallest measurement of a micrometer
Ex : Find the smallest measurement of a linear scale unit divided into 1 mm and 100 micrometers.
Smallest measurement = The length of a linearly scaled section / Number of the deviations on the circular scale
=1 / 100 =0.01mm
How to read measurements of an object with a micrometer.
- Find the thickness of a beam
- Take a beam and place it on the micrometer and rotate it until the anvil and spindle are attached.
- Then note the text that appears on the linear scale of the micrometer.
- After multiplying the circumference by the smallest measurement that corresponds directly to the value of the linear scale.
- Then add the two values.
3.5mm = 0.31 = 3.81mm
- There are two main types of micrometer linear scale, 1mm micrometer, and 0.5mm micrometer. It detects that the linear size of the micrometer at 1mm is just above the horizontal line and the 0.5mm micrometer is calibrated up and down the horizontal line.
Uncertain errors ( Micrometer Screw Gauge)
When using the micrometer, the error of not being able to determine the approximate value of the linear horizontal line is the uncertainty error. This is an accidental error. It can not be removed.
When the ankle and spindle of the micrometer screw are made to touch, the zero of the main scale must correspond to the zero of the circular scale. However, due to wear and tear or product defects, drag zeros are usually out of proportion to each other, and Werner is said to have zero error. There are two types of zero errors
- Positive zero error
- Negative zero error
Positive zero error
- If the ankle and spindle are tied together by the micrometer screw, the zero error is said to be positive if the circular zero marks are below the main scale line.
- When a measurement is taken, the measurement is said to increase.
- The thickness increased by that measurement should be reduced.
- To measure the Zero error, add anvil and spindle and get the same measure.
Negative zero error
In this case, the measure obtained by the anvil and the spindle is less than the actual measurement. This is known as negative zero error.
- It is found by having the 0 points on the linear scale added by the spline and the curve.
- Then you have to add that reduced value.
- To find that shorter length, add anvil and spindle and use the following method.
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