Starrett 749.1 - Section 3 How to Read a Depth Micrometer; Depth Micrometer Head, English

749.1 User Guide 8 Ver 1.0
The L. S. Starrett Company 6/8/2023
Section 3 How to Read a Depth Micrometer
75 Thousandths
line (.075”)
3.0 Depth Micrometer Head, English
• The Depth Micrometer scale reads from right to left.
• Fig.12B, The Reading line on the Sleeve is graduated to 25 thousandths (0.025"). Every fourth line which is longer than the
others, designates a hundred thousandths.
For example: the line marked "3" represents 3 hundred thousandths (.300") etc.
• Fig.12C, The Thimble is divided into 25 equal parts, each line represents 1 thousandth (.001") and it is
numbered consecutively.
• Each revolution of the thimble (0.000” to 0.000”(0.025”)) is equal to the distance from line to line graduated on the Sleeve
(0.025").
Thimble
Sleeve
0
5
6
7
8
9
23
24
1
2
3
4
5
0 4
3
2
1
The Reading Line
Sleeve
Thimble
.025” Line
.050” Line
.100” Line
.024”
.005”
.001”
(0.0 or .025”)
4 Hundred Thousandths
line (.400'')
8 Thousandths
line (.008”)
Fig.12A
Fig.12B, Sleeve
Fig.12C, Thimble