Figure 3-67. Placing Snap Gauge on Cylindrical
Figure 3-68. Correct GO Dimension for
Figure 3-69. Correct NO-GO Dimension for
When snap gauges are stored, arrange
them neatly in a drawer or case so that they do not contact
other tools or each other.
Always hold the gauges in your hands
when checking. Never clamp them in a vise.
At frequent intervals, check all gauges
for accuracy and wear with gauge blocks or master gauges.
3-17. Thickness Gauge. The thickness gauge consists of
thin leaves, each ground to a definite thickness which is
marked on the leaf. The leaves are usually in sets, with
one end of each leaf fastened in a case. Figure 3-70
shows a typical thickness gauge.
Use. The thickness gauge is used to measure
the clearance between two surfaces, such as checking
piston ring gap clearance in a cylinder bore. Another
typical use is shown in figure 3-71.
Ensure that the leaf is clean before inserting it
into an opening.
If a leaf of the proper thickness is not
available, two leaves may be used, the dimensions of
which add up to the required clearance.
Exercise care when using thickness gauges to
measure clearance of knives and cutters on machines. Do
not lower knife on the leaf and then try to remove the
gauge. The leaf may be shaved off if it is too tight.
Never use thickness gauges for cleaning slots
Care. Observe the following practices for the
care and upkeep of thickness gauges:
Coat metal parts of thickness gauges
with a light coat of oil to prevent rust.
Store gauges in separate containers.
Do not drop thickness gauges. Small
nicks and scratches will result in inaccurate measurements.