| The uses
of working gage blocks are as varied as the number of gage blocks in a large
set. The working blocks have an intermediate grade and are often used in the
inspection or calibration lab, but they may also be found on the shop floor.
As part tolerances become tighter and the resolution of comparative gaging
becomes higher, the use of working gage block sets for toolmaking and part
inspection is widespread.
Of course, the most
common use of the gage block is to provide a reference for direct
measurement of distances between parallel surfaces, such as widths of
grooves. The blocks can be used as a go/no go gage or as a means of setting
up a comparative measurement. The ability to stack the gage block set to any
length makes the gage invaluable as a tool in the inspection lab.
Another important use
of the working block is for checking the performance of hand tools and
gaging equipment. Micrometers and other hand measuring instruments can be
checked for linearity (degradation of the micrometer thread). Using gage
blocks of different sizes that are stepped, usually in equal increments over
the measuring range of the measuring tool, provides a means for checking the
performance of the tool. The gage blocks are also useful for setting a
reference point on measuring tools where the measuring capacity of the gage
is larger than the measuring range of the gage itself. For example, a 3-inch
gage block would be used to set the 3-inch reference point on a 3 to 4-inch
micrometer. With these measuring tools, the spindle does not touch the fixed
contact, so a gage block provides a precision method of setting a starting
point.
Limit gage sets can be
created with two sets of gage blocks or gage block stacks set to the high
and low tolerance limits. These sets would consist of gage block stacks with
added contact elements or end jaws combined to the limits specified. They
provide an easy-to-assemble and reliable means of producing temporary gaging
for an unexpected application. In the long run, however, it is more
economical to have a fixed gage made for these applications, as assembly and
disassembly is time consuming and subject to stacking error.
In inspection, a
frequent use of these blocks is to set up for comparison or transfer
measurements during surface plate work. Using a single block or stack for a
height reference is the common approach. By adding another gage block or end
jaw that overhangs the block, an inside dimension can be established. A
base, holding rods and end jaws are often found in a gage block accessory
kit. They allow the assembly area to perform medium accuracy comparisons
with surface plate work. Finally, the use of gage blocks and a sine plate on
the surface plate create a very precise angle setup. The double requirement
of accurate length and perpendicularity to the base is a perfect use of the
working gage block. Using fairly straightforward trig, the right angle
reference set up by the blocks and the known length of the sine plate make
for easy angle setup.
Gage blocks need
preparation before they can work. The process includes making sure that they
are recently certified, checked for nicks and burrs and stabilized for the
temperature of the work area.
With care and careful
handling, working gage blocks can contribute significantly to a
manufacturer's productivity. |
