# Commented exercises of reading and interpretation of micrometer in thousandth inch

## Commented exercises of reading and interpretation of micrometer in thousandth inch

From website: www.stefanelli.eng.br - prof.: Eduardo Stefanelli

sleeve scale thimble scale

x
0.1in
+
x
0.025in
x
0.001in
sleeve scale
+
thimble scale
+
interpolation
+
frame
0
+
0
0
0.0   +
(0) 0.000 +
0.000 +
0.0   =
0.000in
this instrument is calibrated and ready for use. The vertical mark is partially revealed by the edge of the thimble, this condition varies depending on the setting and the condition of the micrometer. It is good practice to analyze how this mark is presented before starting the measurement.
0
+
1
0
0.0   +
(1) 0.025 +
0.000 +
0.0   =
0.025in
see it revealed the first vertical mark, remember that the inch was divided by ten (tenth) and each of these divisions was divided by 4 (0.1 / 4). The 'zero' thimble is aligned. This indicates that the thimble has a full rotation (360°). Also note that the perimeter of the thimble scale for 25 divisions. This means that each division comprises 0.001in (0.025/25).
0
+
2
0
0.0   +
(2) 0.050 +
0.000 +
0.0   =
0.050in
see it revealed the second vertical mark, indicating that the thimble has two turns. The thimble scale has 25 divisions
2x25 = 50 thousandths of an inch or half-tenth inch.
0
+
3
0
0.0   +
(3) 0.075 +
0.000 +
0.0   =
0.075in
see it revealed the third vertical mark, indicating that the thimble has three turns. The thimble scale has 25 divisions
3x25 = 75 mils.
1
+
0
0
0.1   +
(0) 0.000 +
0.000 +
0.0   =
0.100in
see it revealed the fourth vertical mark (the first numbered tenth of an inch, this reference helps you unconcerned with intermediate traits), indicating that the thimble has four turns.
Note that the first number indicates tenths of an inch is visible as well: 1x0.1 in = 1 tenth of an inch or one hundred thousandths of an inch.
1
+
0
12
0.1   +
(0) 0.000 +
0.012 +
0.0   =
0.112in
the tenth of an inch follows the logic of the previous exercise, the 12 mils are read in the thimble scale, see who is the 12th division of the thimble scale is aligned with the zero line of the sleeve scale.
1
+
0
7
0.1   +
(0) 0.000 +
0.007 +
0.0   =
0.107in
the tenth of an inch follows the logic of the previous exercises, the seven mils are read in the thimble, see who is the 7th division of the thimble scale is aligned with the zero line of the sleeve scale.
6
+
0
10
0.6   +
(0) 0.000 +
0.010 +
2.0   =
2.610in
the six-tenths of an inch follows the logic of the previous exercises, the ten thousandths of an inch are read in the thimble scale, see who is the 10th division of the thimble scale is aligned with the zero line of the sleeve scale. The two inches whole can be read both in the sleeve scale (2 instead of 0) and labeling of the range of the instrument has the range 2 to 3 inches, in the frame.
8
+
3
20
0.8   +
(3) 0.075 +
0.020 +
1.0   =
1.895in
The eight-tenths of an inch follows the logic of previous exercises after eight sleeve scale displays three vertical marks 3x25 = 75 mils, is added to these 75 to 20 mils indicated in the thimble scale. The whole inch is inferred by the 'range' of the micrometer.
3
+
2
12
0.3   +
(2) 0.050 +
0.012 +
3.0   =
3.362in

5
+
2
9
0.5   +
(2) 0.050 +
0.009 +
0.0   =
0.559in
The five tenths of an inch follows the logic of previous exercises after five sleeve scale exhibits two vertical marks: 2x25 = 50 mils, is added to these 50 mils 9 mils indicated in the thimble scale.
2
+
1
12
+
(5)
0.2     +
(1) 0.025   +
0.012   +
0.000(5)+
2.0      =
2.237(5)in

4
+
0
23
+
(3)
0.4     +
(0) 0.000   +
0.023   +
0.000(3)+
0.0      =
0.423(3)in
four-tenths of an inch, then it does not display the sleeve scale vertical marks: 0x25 = 0.000, sum up 23 mils indicated in the thimble scale, but it is clear that the 23 'went' a bit line and the 24 'did not come' to zero line in the sleeve scale, which was played before halfway, hence the (3) ten-thousandths.
7
+
3
11
+
(7)
0.7     +
(3) 0.075   +
0.011   +
0.000(7)+
1.0      =
1.786(7)in
seven-tenths of an inch, then it displays the sleeve scale three vertical marks: 3x25 = 75 mils, sum up these 75 mils 11 mils indicated in the thimble scale, but it is clear that the 11 'pass' line and the 12 'has not arrived' the zero line in the sleeve scale, interpreted that went half way, then the (7) ten-thousandths.
The whole inch is the 'range' in the 1-2 micrometer.
obs. x
0.1
+
x
0.025
x
0.001
+
x
0.0001
sleeve scale
+
thimble scale
+
interpolation
+
frame