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From the Archive |
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Excerpt from Popular Mechanics Shop Notes, Volume 21,
1925.
Measuring Irregular Objects
Accurate measurements of irregular objects can be made quickly
and easily with the aid of photography. The illustration shows
the method of doing this, and the inserts show some of the
work.
The
sensitized paper is put in a printing frame and this is
laid face up on a table. The object is then placed on
the paper and a cardboard tube of suitable diameter to
fit within the frame is set up as indicated. The printing
is done by holding an electric lamp at the other end of
the tube for about 30 seconds. Care must be taken to hold
the lamp over the center of the tube so that the rays
striking the paper will be nearly vertical.
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Printing Outline of Irregular Objects on
Sensitized Paper to Aid in Measuring Them. |
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The
inside of the tube should be painted dull black to prevent reflection.
After exposure, the paper is developed in the usual way and
an accurate outline of the object will show up on the prints.
By this method gear wheel teeth, keys, etc., can be measured
much more quickly than by using a scale and calipers. When very
accurate measurements are required, as is the case with small
clock gears, etc., film should be used instead of paper and
the resulting negative should then be enlarged. |
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Editor's
Note: This is a reprint of an article published in 1925. It
describes what was recommended in accordance with the knowledge
and practices of the day. While reading it, please consider
this fact. |
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Other Articles from this Issue |
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