USE/CARE OF HANDTOOLS & MEASURING TOOLS - OD1621 - LESSON 3/TASK 1
FIGURE 177.
TRAMMEL SET.
an outside or inside caliper or to a hermaphrodite caliper. Ball points are
used to position a tram in the center of a hole. By using different size
balls or V-points, it is possible to position the tram in any size hole up
to 1 1/2 inches in diameter. On top of the trams are knurled handles which
swivel so that the handles may be gripped firmly when describing a circle or
an arc. An adjusting screw is provided on one of the trams which permits a
fine adjustment of the points.
(6) Vernier Calipers. This type of caliper uses the Vernier scale.
The Vernier scale consists of a short auxiliary scale usually having one
more graduation in the same length as the longer main scale.
The Vernier
caliper (figure 178 on the following page) consists of a L-shaped frame, the
end of which is a fixed jaw; the long arm of the L is inscribed with the
main true scale or fixed scale. The sliding jaw carries the Vernier scale
on either side. The scale on the front side is for outside measurements;
the scale on the back is for inside measurements. On some Vernier calipers,
the metric system of measurement is placed on the back
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