Illustrated history of the United States mint: with a complete description of American coinage, from the earliest period to the present time — John Shaqi
Illustrated history of the United States mint: with a complete description of American coinage, from the earliest period to the present time
History
Illustrated history of the United States mint: with a complete description of American coinage, from the earliest period to the present time
Coinage -- United States; Mints -- United States
These machines resemble long tables, with a bench on either side, at one
end of which is an iron box secured to the table. In this are fastened
two perpendicular steel cylinders, firmly supported in a bed, to prevent
their bending or turning around, and presenting but a small portion of
their circumference to the strip. These are exactly at the same distance
apart that the thickness of the strip is required to be. One end of the
strip is somewhat thinner than the rest, to allow it to pass easily
between the cylinders. When through, this end is put between the jaws
of a powerful pair of tongs, or pincers, fastened to a little carriage
running on the table. The carriage to the further bench is up close to
the cylinders, ready to receive a strip, which is inserted edgewise.
When the end is between the pincers, the operator touches a foot pedal
which closes the pincers firmly on the strip, and pressing another
pedal, forces down a strong hook at the left end of the carriage, which
catches in a link of the moving chain. This draws the carriage away from
the cylinders, and the strip being connected with it has to follow.
It is drawn between the cylinders, which operating on the thick part
of the strip with greater power than upon the thin, reduces the whole
to an equal thickness. When the strip is through, the strain on the
tongs instantly ceases, which allows a spring to open them and drop the
strip. At the same time another spring raises the hook and disengages
the carriage from the chain. A cord fastened to the carriage runs back
over the wheel near the head of the table, and then up to a couple of
combination weights on the wall beyond, which draw the carriage back to
the starting place, ready for another strip.
[Illustration: DRAWING BENCH.]
THE CUTTING MACHINES.
After being thoroughly washed, the strips are consigned to the cutting
machines. These are in the rear of the rolling mills, and are several in
number, each when in active operation cutting two hundred and twenty-five
planchets per minute. The press now used, consists of a vertical steel
punch, which works in a round hole or matrix, cut in a solid steel plate.
The action of the punch is obtained by an eccentric wheel. For instance,
in an ordinary carriage wheel, the axis is in the centre, and the wheel
revolves evenly around it. But if the axis is placed, say four inches
from the centre, then it would revolve with a kind of hobble. From this
peculiar motion its name is derived. Suppose the tire of the wheel is
arranged, not to revolve with, but to slip easily around the wheel, and a
rod is fastened to one side of the tire which prevents its turning. Now
as the wheel revolves and brings the _long side nearest the rod_, it will
push forward the rod, and when the long side of the wheel is _away from
the rod_, it draws the rod with it.
[Illustration: CUTTING MACHINE.]
[Illustration: STRIP FROM WHICH PLANCHETS ARE CUT.]
Public-domain text, read in full here on John Shaqi.
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