Use of Gages - Continued
The following is a recommended procedure for obtaining a correct reading on the micrometer barrel.
Find the largest number graduation on the revolution line between 0 and the edge of the thimble.
Find the number of unnumbered graduations between the largest numbered graduation and the
edge of the thimble.
Find the number of graduations on the thimble, taking careful note of 0 on the thimble in relation to
the revolution line on the barrel.
Example 1: (fig. 4-10)
The thimble has been turned counterclockwise through twelve complete revolutions and the edge of
the thimble is directly over the third numbered graduation or the barrel. The 0 on the thimble is
directly over or coincides with the revolution line on the barrel. The correct reading in this particular
instance is 0.300 inch.
Figure 4-10. Micrometer Barrel Setting - .300 inch