Introduction
Hack Sawing Efficiency is important to every machine
shop owner and metal worker because it is so very
necessary for them to know whether they are buying the
most efficient blades and using them in the most
efficient way.
To know this is important, not because
each blade is a big cost item in itself - though it is
surprising how fast poor blades run into real money -
but because the work that hack saws do or fail to do in
a shop of even moderate size involves thousands of
dollars, in time of men and machines and profits won or
profits lost.
For some reason the study of hack saw
efficiency has received probably less thought and
attention from engineers and investigators than any form
of metal working as is shown by the almost total lack of
books and magazine articles on the subject.
It may be this is because the low cost
per blade has made the question seem relatively less
important, or because the efficiency pioneers like
Taylor and Gantt happened to devote their years of study
and experiment to other kinds of metal cutting.
The fact of course is that hack sawing
is very important - as important as any other metal
working operation and the purpose of our $500 prize
contest on “Testing Hack Saws” was to emphasize this
importance and bring the latent interest on the subject
to the surface.
Following this we planned to publish a
book such as this to put in available form standardized
hack saw information that would have a permanent value.
The contest was all we had hoped and more. We were
almost swamped with replies which came from every corner
of the world. Many were of real scientific value and
they showed that more thought and study has been
 put
on hack sawing efficiency by users and investigators
than was generally realized by the American engineering
and industrial world.
Our contest has disclosed the fact, for
instance, that in England a mammoth power machine has
been developed that cuts work up to 26 inches square and
a special English hack saw testing machine has been
devised that is entirely automatic both in operating
successive cuts and recording the time of the results.
Our original intention was to publish
complete the papers of all the prize winners in our
contest but we find that this would make a book of
impossible size that will have much repetition and some
confusing contradictions.
Hence it has seemed best to give a
standard outline of the best method to test and use hack
saws based on our 30 years experience, adding notations
of any special methods or novel ideas that the prize
winners have evolved.
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