of Gauge blocks is to provide a linear reference
dimension to very close tolerance. Gauge
blocks are used for calibrating measuring
instruments, such as micrometers and calipers.
Gauge blocks are rectangular
or square steel blocks with a very accurate
width. They are sold in sets; a typical
set has 91 pieces with widths varying from
0.010 to 0.100 in steps of 0.001.
Several blocks are stacked
to give the required overall dimension.
The surfaces of the blocks are extremely
flat and highly polished. The blocks are
placed together, so that the faces overlap,
and then slid into alignment. This creates
a vacuum between the faces that makes them
stick together, they can only be disassembled
with a sliding action. This method of stacking
the blocks is known as 'wringing'
There are four grades of blocks:
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