The depth
micrometer
is a tool used to measure the distance between two parallel
surfaces. Depth micrometers have the same thimble and sleeve as
other micrometers and are made to take readings in either inch or
metric units. They come in sets with different length depth rods
for different ranges of measurement.
To measure with a depth micrometer , place the base on one surface
to be measured . Then rotate the thimble to move a depth rod down
to the lower surface. The distance the rod moves down is the
depth. The depth is read just like any micrometer measurement on
the thimble and sleeve.