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284 Raging- Stamping - Heaf Treating
New Rockwell Hardness Tester
The latest model of the Rockwell Hardness Tester
is quite an elaborate machine compared with any of
the earlier standard models and has been designed
specially for testing very large pieces. In all of the
smaller models of the Rockwell the work being tested
is elevated into contact with the penetrator, but in
this new model provision is made for lowering complete
testing head so that the penetrator is moved
into contact with the work being tested.
The first three of these new universal models have
been made for large automobile companies for testing
the hardness of automobile cylinder block castings.
In some instances machined castings are tested and
in others unmachined castings.
The threaded columns and testing bridge of the
tester in the illustration shown are standard, but the
length of those columns and their distance apart are
obtainable to suit special requirements. The base
shown into which the columns are set is simply a shop
tool for testing out the accuracy of each D U machine.
These universal machines have been made only for
New Rockwell hardness tester.
those several companies who have undertaken to
make their own bases, and as the D U machines have
been used principally for hardness tests on automobile
engine cylinder blocks the bases made by the
users have been designed to fit into their production
train.
By turning the crank handle the whole testing head
is raised and lowered and both the principle and accuracy
of test are the same as in the smaller sizes of
the Rockwell Tester. Readings on large and small
machines are alike, as the same penetrators and loads
are used. In these universal machines the testing
head is lowered with pressure against the work to be
tested instead of elevating the work against the test
point, for application of the "minor" load.
In considering both the design and cost of these
machines it is to be kept in mind that 100 points of
hardness on the Rockwell scale is equivalent to a total
depth of penetration of only .008 in. so that two points
difference in hardness means difference of depth of
impression of only .00016 in. These large machines
are really giant micrometers of a high order of ac­
August, 1925
curacy, and the testing head must elevate and lower
without any measurable "back-lash" or "lost-motion."
The helical springs between the nuts on the
threaded columns press the testing bridge always upward
against the lower surfaces of the threads of the
columns. Ball bearings are introduced as points of
greatest friction.
This universal model is useful not only for large
castings but for testing circular saws, say, 72-in.
diameter, which are too heavy and too great in area
to consider elevating to meet the penetrator.
A Binocular Magnifier
In certain industries where visual examination is
necessarily employed by mechanics and machinists at
lathes and at other tools in order to gage the progress
of precision work, eye strain and fatigue often result
from the smallness of the product to be examined. To
correct this difficulty a new instrument, known as the
"binocular.stereo magnifier," has been put on the market
recentlv by E. Leitz, 60 East 10th Street, New
.
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Binocular stereo magnifier.
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York. It is claimed that, by the use of this new in
strument, the minutest parts can be inspected and
technical details controlled, as well as the smallest
units adjusted to their relative position in an accurate
and reliable manner.
The new instrument is descibed as producing a
stereoscopic image which shows the object under examination
in plastic relief, sharper and clearer than
by the naked eye. It is suggested that the use of
this instrument may eliminate some of the large losses
in production, and that there will be a diminution in
the constant falling off in efficiency and quality of production,
due to poor vision.
The new magnifier is furnished for use with a
variety of different stands to suit each particular requirement
and, since the prism body can readily be
interchanged with any stand offered, a saving in cost
of installation will always prevail. It is pointed out
that when using the binocular magnifier the object is
reproduced in its actual orientation, or, in other words.
in the identical position as seen with the naked eye.
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