18
CHAPTER ONE
Vernier scale
34
1. Largest number visible on sleeve line Sleeve Thimble 2. Number of sleeve marks visible between the numbered sleeve mark Vernier scale and the thimble edge 3. Thimble is between 0.018 and 0.019 in. on the sleeve line 4. Vernier line coinciding with thimble line Total reading
Sleeve
35
0.100 in.
0.050 in. 0.018 in. 0.0003 in. 0.1683 in.
Thimble
STANDARD METRIC MICROMETER
Anvil
Locknut Sleeve line Thimble Spindle
Sleeve marks
Thimble marks
Ratchet
The vernier scale consists of 11 lines marked 1-9 with a 0 on each end. These lines run parallel to the thimble lines and represent 0.0001 in. increments.
amount in ten-thousandths of an inch to add to the initial reading from Step 1.
When reading a vernier inch micrometer, perform the following steps while referring to Figure 34.
Metric micrometer
1. Read the micrometer in the same way as a standard micrometer. This is the initial reading. 2. If a thimble mark aligns exactly with the sleeve line, reading the vernier scale is not necessary. If they do not align, read the vernier scale in Step 3. 3. Determine which vernier scale mark aligns with one thimble mark. The vernier scale number is the
The standard metric micrometer (Figure 35) is accurate to one one-hundredth of a millimeter (0.01-mm). The sleeve line is graduated in millimeter and half millimeter increments. The marks on the upper half of the sleeve line equal 1.00 mm. Every fifth mark above the sleeve line is identified with a number. The number sequence depends on