# Micrometer Screw Gauge

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.

#### Zero errors

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

1. Positive zero error
2. 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.