Evening star., 1922-05-27
BY A. HYATT VERRILL,
Expert on Radio Technology.

To cut and drill glass:
Although glass is not so widely used
in radio work as wood and metals, yet
for many purposes it is superior to
either. Under some conditions glass
must be drilled or cut into irregular
shapes. Most people think it very
difficult matter to work glass because
it is hard and brittle But, if you know
how, glass is as easy to cut, file, bore
or work as brass or iron, in fact, easier.
Once you are in the know and have had
little practice, you will find it no more
difficult to work glass than hard wood.
For cutting ordinary fiat glass into
forms with straight or curved edges.
the diamond is the best tool, but a ten
cent carburundum diamond will. give
just as good satisfaction as the real
stone. 1t takes a little knack and prac-
, tice to cut piece of glass smoothly and
evenly with diamond, but by practic-
ing on some odds and ends you will
soon learn the right angle at whcih to
| hold the tool and the pressure you
should use as you draw it over the glass.
But remember that you never should go
over the same mark twice. This Injuries
the cutter and does not make the glass
cut any easier.
| the glass will break easily along the
line. AS you become accustomed to
doing this, you will know by the clear
musical note made by the cutter, wnen
it is cutting properly and by an uneven
Scratchy note when il is not cutting,
but is merely scratching.
Very often, you may have need to
trim off rough edges or corners from
piece of glass or you may wish to cut
a small piece into a circle. oval or other
tFyt To do h ri dIlr
very difficult. if not impossible, but it
may easily be accomplished by using or
j dinary scissors. shears or cutting pliers.
Have the tools dull rather than sharp
and do the cutting under water. A lit
tie practice will enable you to Shape
small round or oval with ease, rapidity
and precision in this simple matter.
Another method which is particu-
larly useful in cutting bottles or
TASKS is TO use a red-hot iron wNh
with this first mark where you wish
to cut with chalk, or paste strip OF
paper as guide, and start the cut
with a file. Then apply the red-hot
| iron and instantly a crack will start
which will follow the hot iron where
ever you desire to lead it. In this
| way old bottles may be made into
jars, dishes. etc. With a little prac-
tice yiu will find you can easily cut
spiral of glass from round bottle
and. strangely enough. you VIII fnd
that such a spiral is quite elastic
that the coil of glass may be stretch
ed out for for some distance without
breaking, exactly like metal spring.
The same hot iron method may be
used in cutting fiat sheet glass into
intricate forms and patterns.
1t is far more important. however,
to know how to drill glass than to
cut it. This is very easy if you use
a well tempered drill and keep it
moistened with a mixture of camphor
and turpentine. An even better lubri-
cant is a weak solution of sulphuric
acid. In German and Bohemian glass
factories glass is drilled, planed, cut
and turned on lathes and in machines,
as readily as soft metal. merely by
keeping the cutting tools moistened
with the diluted sulphuric acid. Re
soda and water after using and wipe
off with a well oiled rag. Otherwise
they will rust and be ruined. Glass
may also be filed and sawed. using
sharp file or hack saw, by means of
the acid treatment.
To Render Wood Waterproof.
1t is very important matter to
have all wood or cardboard used
about radio sets inpervious to water
or moisture. Ordinarily. cardboard is
treated with melted paraffin to ac-
or cardboard absolutely moisture and
water proof, soak in this mixture:
Zinc chloride, parts; ammonium
chloride, parts: sodium borate, 3
parts, and water 100 parts. After
| treatment, the wood may be shellack-
ed or vanished or otherwise finished
! to suit your taste.
Attaching Metal to Wood.
Very often it is difficult to fasten
metal, rubber or celluloid to wood
with an ordinary adhesive such as
glue paste. rubber cement, etc. But
| here is tried and proven method: ::
Dissolve fifty parts of lead acetate
(sugar of lead) and five parts of
alum in a little water.Then make a
solution of seventy-five parts of gum
arabic in 1000 parts of water, and
add gradually, while constantly STIR
ring and heating, 500 parts of flour.
! Keep the mixture stirred well until
boiling and then add the first solu-