Made from Electric Bell [94]

It is not necessary to remove the adjusting-screw when changing an
electric bell into a relay. Simply twist it around as at A and
bend the circuit-breaking contact back as shown. It may be
necessary to remove the head of the screw, A, to prevent
short-circuiting with the armature.
--Contributed by A. L. Macey, New York City.

[Illustration: Relay]

** Foundry Work at Home [95]

** I The Equipment [95]

Many amateur mechanics who require small metal castings in their
work would like to make their own castings. This can easily be
done at home without going to any great expense, and the variety
and usefulness of the articles produced will make the equipment a
good investment.

With the easily made devices about to be described, the young
mechanic can make his own telegraph keys and sounders, battery
zincs, binding posts, engines, cannons, bearings, small machinery
parts, models and miniature objects, ornaments of various kinds,
and duplicates of all these, and many other interesting and useful
articles.

The first thing to make is a molding bench, as shown in Fig. 1. It
is possible to make molds without a bench, but it is a mistake to
try to do this, as the sand is sure to get on the floor, whence it
is soon tracked into the house. The bench will also make the
operation of molding much easier and will prove to be a great
convenience.

The bench should be made of lumber about 1 in. thick and should be
constructed in the form of a trough, as shown. Two cleats, AA,
should be nailed to the front and back to support the
cross-boards, BE, which in turn support the mold while it is being
made. The object of using the cleats and removable cross-boards
instead of a stationary shelf is to give access to the sand, C,
when it is being prepared.

About one or two cubic feet of fine molding-sand will be required,
which may, be purchased at the nearest foundry for a small sum.
Yellow sand will be found a little better for the amateur's work
than the black sand generally used in most foundries, but if no
yellow sand can be obtained the black kind will do. If there is no
foundry

[Illustration: Fig. 1 - Convenient Arrangement of Bench and Tools]

near at hand, try using sand from other sources, giving preference
to the finest sand and that which clings together in a cake when
compressed between the hands. Common lake or river sand is not
suitable for the purpose, as it is too coarse a