This page assumes that you have already interacted with the page: micrometer in millimeter hundredth resolution - use, reading and interpretation and with the page: reading of ruler or line gauge, in tenth inch.
figure 1 - thimble in partial view to reveal the shealth marks
A complete turn in the thimble (and of the fuse) produces the advance equal to the thread pitch. The screw of this fuse, usually, has the lenght of the one inch and the pass of 25 thousandths of inch.
In the sleeve it has a graduation that controls the advance os the thimble/fuse - figure 1. The inch (the 10 tenths) is divided by nine main marks, the distance between them is the tenth of inch, these marks has numbers to help the reading. The tenths of inch are divided by three marks that control the advance of twenty and five thousandth of inch (0.1/4 = 0.025in). This means that each time that a new mark is revealed by the thimble, the fuse moved close to twenty and five thousandth of inch(0.025in).
The configuration more used in the metal/mechanic offices is the fuse micrometric has the pass of 0.025in and the thimble 25 divisions - figure 2. This way, when you turn the micrometric fuse each mark of the thimble that pass by the 'refference line' will show that the mobile jamb moved out (or got closer) 0.001in (one thousandth of the inch).
figure 2 - image of the graduation of the thimble corrected to reveal the 25 marks/divisions
- to determin the value of the measure, it is necessary to sum:
- click in the icon in the inferior corner of the interactive screen animation to alternate the value of the measure
- use the ison 'eye' to hide the values total and partial
- with the 'eye closed', click in the colored circles to show the value related to them
The conprehension of the reading of this instrument is very intuitive for whom knows the vernier scale: simulator of reading and interpretation in thousandth inch resolution 0.001" . Evidently, it is necessary to transfer the manipulated data given by the vernier to the given one by the thimble. See also the figure 2 of the page: Micrometer in inch with resolution tenth of thousandth - use, reading and interpretation