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 canter, 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.
The
upper shaft, on which are seen the three large wheels, has
also fastened to it over each press, an eccentric wheel. In
the first illustration will be seen three upright rods running
from near the table to the top. The middle one is connected
with a tire around the eccentric wheel, and rises and falls
with each revolution. The eccentric power gives great rapidity
of motion with but little jerking.
The
operator places one end of a strip of metal in the immense
jaws of the press, and cuts out a couple of planchets, which
are a fraction larger than the coin to be struck. As the
strips are of uniform thickness, if these two are of the right
weight, all cut from that strip will be the same. They are
therefore weighed accurately. If right, or a little heavy,
they are allowed to pass, as the extra weight can be filed
off. If too light, the whole strip has to be re-melted. As
fast as cut the planchets fall into a box below, and the
perforated strips are folded into convenient lengths to be
re-melted. From a strip worth say eleven hundred dollars,
eight hundred dollars of planchets will be cut.
