The Monmouth inquirer., 1923-07-19
Above Illustrations Show Method Of
Constructing Form and Means Of
Winding Coil.

Two end pieces of suitable size are
made from this board, and a quarter
inch hole is bored in the center of
each. One end piece Is screwed to
each end of the core, It's center hole
coinciding with that in the core. The
spool thus formed is slipped onto a
quarter-inch rod which has n end
threaded for several inches and the
other bent in the form of d crank. A
tap is screwed up tightly to each end
of the spool, and the whole is mount
ed as shown in Fig. 2. The bearings
are simply wooden uprights with hole
for the axle. If all work has been
done with reasonable accuracy the
spool should show no tendency to
wobble when the crank Is turned.
The first step before winding the
coil is to be sur that 1t will slip of
the core readily when 1t Is finished.
Wind on the core a single layer Of
small hard-twisted cord. This layer
must be wound perfectly smooth, and
the ends should be brought out
through small holes in the end pieces.
Wrap upon this layer two or three
thicknesses Of thin, stiff paper, just
wide enough to come flush against
both ends. Glue both tabs of the pa
per slightly, just enough to hold 1t
in place.
On each side of the core and paral-
lei to the axis glue a strip of narrow
cloth tape, as shown at A, Fig. 2, al
lowing each end to come up from the
core along the end pieces, and fasten
temporarily upon the outside. The
tape ends must be Of sufficient length
to tie over the coil when 1t is wound,
thus providing a method Of binding it
tightly in the process of removal. If
the coil is to be a large one, two or
more pieces of tape should be placed
on each side of the form. After these
binders are in place paint the core
with shellac or insulating paint.
Pass one end Of the wire to be
wound through a small hole drilled
through one end-piece. Draw several
inches of wire through and fasten
securely by wrapping around the
shaft. Wind the required number Of
turns on the spool, laying each turn
as closely as possible against the pre-
ceding one. Paint each layer, as It Is
wound. with a liberal coat of insulat-
ing paint and allow It to partly dry
before putting on the next layer.
Wire-especially enameled wire-may
be placed much more satisfactorily If
1t is wound on a bed Of paint which
has been allowed to dry just to the
point of tackiness. When all the
winding is in place paint the last lay
err, release the tab ends and tie each
piece Of tape firmly across the coil,
as shown In Fig. B.. Allow time for
the paint to harden before removing
the coil. Passing just sufficient cur
rent through the coil to warm up the
wire will hasten the drying.
Take the form from the axle, re-
move n of the heads and grasp the
end of the layer of string. BY pull
ing in the direction parallel to the
axis the string nay be removed, thus
leaving a free space between the coil
and the core. Remove the coil from
the core, tape 1t and it is finished.
In the final tapping the binding tabs
should be removed, but 1t is not nee
essary to remove the paper. Narrow
tape is best and makes a much neater
Job on small coils. Each turn should
overlap the preceding one by half its
width. Going ace around the coil
with tape in this way gives two thick
nesses at every point, and this Is
usually sufficient.
20 Science aad Invention and Radio Newsl