MAKING A MODEL
At the end of the chapter on drawing I explained how you could make
models of mechanical movements of cardboard. And you will remember that
the purpose of these simple models is to clear up points that are hazy
when you are working out your invention on paper.
~Kinds of Models.--~Now besides cardboard models there are some other
kinds, the chief ones being (1) _rough models_; (2) _scale models_ and
(3) _working models_, and each of these kinds is useful in its own way.
The kind you should make, or have made, will depend on the bulge of
your pocketbook as well as on the nature of your invention as you will
presently see.
There was a time when the United States patent office required a model
of every invention for which a patent application was made; as a result
the noble patent office finally became a museum filled with antique
models instead of an office in which business was transacted for and
with inventors.
The government officials then concluded that the _patent examiners_
didn’t really need to see the models anyway and then and there they
ordered that a patent application only need be sent to the patent
office--with one exception; this exception is made when a would-be
inventor applies for a patent on a perpetual motion machine and then
he is asked for a _working model_ and if this is not forthcoming--and
of course it never is--no further attention is paid to him or to his
application.
[Illustration: FIG. 64. A ROUGH MODEL OF AN ELECTRIC MOTOR DRIVE FOR A
LOCOMOTIVE]
~Rough Models.--~After you have made the drawings and experiments which
your invention calls for and both have worked out to your satisfaction
you will then have a burning desire to see the result of your efforts
in a more substantial form.
Some machines in which there are only a few moving parts need not be
built up very carefully, or to exact scale or even of the materials the
marketable product is to have in it. Very often a model can be made of
wood and scrap metals that will do and show everything that you want it
to. See Fig. 64.
Should you have to employ a patent attorney who lives at a distance
from you, say one who has an office in Chicago, Philadelphia or Boston,
a rough model of your invention will be of great help to him for it
will give him an insight into its workings and its possibilities that
he is not apt to get from studying your drawings and description unless
you are a good mechanical draftsman and he is above the average in his
profession.
[Illustration: FIG. 65. A SCALE MODEL OF AN AEROPLANE]
~Scale Models.--~Scale models are usually miniatures of the full sized
machine, that is every part of the scale model is reduced in proportion
from the dimensions of the big machine, say 1 inch to the foot or
whatever you want to make it.
Like rough models scale models need not be actual working models,
indeed in many cases it is very hard if not impossible to make a scale
model which will run or work like a full sized machine, unless the
model is made very large, as for instance model aeroplanes fitted with
motors of any other kind than those made of rubber strands. Fig. 65
shows a scale model of an aeroplane.
[Illustration: FIG. 66. A TOY HELIOCOPTER]
Then again sometimes a scale model will work to perfection and when a
full sized machine is built it will not work at all as in the case of
the _heliocopter_, that is, a flying machine having a screw with blades
like a propeller and which when it is rapidly spun by means of a string
like a top will rise in the air to a height and sail away to a distance
of a hundred feet or more. Fig. 66 shows a toy _heliocopter_, or
aerial top as it is called. Many attempts have been made to build full
sized flying machines on the principle of the toy heliocopter but so
far none of them have been able to get off of the ground.
[Illustration: FIG. 67. A WORKING MODEL OF A BRITISH EXPRESS LOCOMOTIVE]
Then again there are many machines that can be made of any size and
which will work equally well. Fig. 67 is a scale model of a British
express locomotive. It is 4 feet long and an exact scale model which
can be fired up with coal and it will make a speed of 10 miles an hour.
A scale model of your invention, if it is a machine, or an electrical
apparatus, when built by an expert model maker, makes a mighty pretty
display and will never fail to attract attention wherever it may be
shown.
~Working Models.--~A working model may be a scale model as you have
seen or it may be a full sized machine or of any size between these
limits.
When you have your invention past the drawing board and up to the shop
bench by all means make a working model of it and if possible make
it full size. This kind of a model is the proof you want that your
invention will work when it is put to the test and by making a working
model you will find lots of changes little and big that are needed and
which when made will improve its operation wonderfully.
And however carefully you have worked out your invention on paper you
will find that when you come to make a model, or have one made, you
will have to change it not once but many times, that is if it is a
machine in which a number of parts are made use of and you may have to
re-design it and re-construct it several times.
For this reason it is a waste of money to build a fine appearing and
costly model in the beginning but what you should do is to make one
that will work without regard to its looks so that you can experiment
with it, overhaul it, tear it down, build it up again and so on until
you are satisfied with it and the results it produces, if such a thing
is possible, before you even begin to talk to a patent attorney about
applying for a patent on it.
Nearly every _tyro_ inventor seems to believe that the only way to keep
honest folks from stealing his invention is to apply for a patent on
it immediately. You will remember I pointed out in the first chapter
how to protect your first idea by signatures and _affidavits_ and
protection of this kind is just as good, and in my opinion just as
safe, and in every way better than to rush off and apply for a patent
and--though of course money is of no object--it is cheaper by at least
$35.00.
Again as I stated in the preceding chapter if you apply for a patent
before you have made a working model of it you will find when you
finally get your model finished it will be so at variance with what
you have written in your specification and claims that you will hardly
be able to recognize it as being the same invention; and besides there
will be the trouble and the expense of changing your drawings and
specification and claims.
On the other hand when you have finished your model to the point where
it will do the work you want it to do you are in a position then to
make a new and accurate set of drawings, to write a clear description
of how the machine works and to draw up your claims with the certainty
of knowing just what you have and what you want to ask for--in a word
you are ready to do business with the patent office.
~Ways to Make a Model.--~The way in which you get your model made
depends on several things and over these you will have little or no
control.
There are two ways for you to get a model made of your invention and
these are (1) to make it yourself and (2) to have a model maker make it
for you.
These two general ways may be further divided into several sub-ways and
among these are (a) for you to have your own workshop, or laboratory
and hire machinists, or electricians, or chemists, and have them do
the work under your direction; (b) for you to give a model maker the
job and have him, or his men, do it under your supervision and (c) for
you to have separate parts of it made by various model makers and then
assemble them in your own shop.
If you are a little skilled in the use of tools there isn’t anything
I know of that will give you greater pleasure than to make each part
of your model with your own hands in your own shop and watch it grow
day by day until it becomes in truth the very apple of your eye. At
least that is the way I feel about it. Moreover it gives you a sense of
security you cannot have when the work is in some one’s else hands.
In making a machine from your own ideas and plans no one can do the
work so well as yourself provided you can do the work at all and
besides it is cheaper and far more satisfactory.
Should you have a fat pocket-book and at the same time a taste for
inventing and the sciences--these elements seldom go hand in mind--but
if they should get close together in your case I say, the right way to
make a model is to hire skilled men to do the work while you do the
thinking and the assembling in your private lab. By this process your
model will go forward rapidly and the work will be done in the best
fashion.
Before employing any one to work on your invention have him sign this
agreement:
EMPLOYEE’S PATENT AGREEMENT
The undersigned, in consideration of his employment by Charles Basset,
inventor, and in further consideration of the salary received by him
for such employment, hereby agrees that all inventions and discoveries
pertaining to the business of the said Charles Basset which may be
made by him while in his employ shall become the property of the said
Charles Basset.
And further, he also agrees to assign to the said Charles Basset all
applications made by him for _letters patent_ of the United States
and elsewhere and all _letters patent_ that may be granted to him,
covering such inventions and discoveries without further compensation,
and
That he will promptly, on conception of any patentable idea or
invention, disclose the same to the said Charles Basset and on his
request so to do will make application for _letters patent_ covering
such inventions and discoveries;
And further, that he will execute all other papers whatsoever that
may be necessary to transfer to and rest in the said Charles Basset
all the right, title and interest in and to such inventions and
discoveries, it being understood and agreed that all expense incident
to the securing of any _letters patent_ or application for patent
shall be borne by the said Charles Basset.
(Signed) HENRI FABRE.
_Boston, Mass.,
May 26, 1916._
--_Brennan’s Handbook._
The plan of having a model maker do all of the work under your
direction may not appeal very strongly to you but after all, if you
lack the skill and the equipment needed for making your model, it is a
pretty good scheme.
Every large model making establishment has separate rooms fitted up
where each inventor can work on his own machine and this gives you the
privacy you demand and besides whenever you want a part made or changed
you have a skilled mechanic at your beck and call and a shop equipped
with the finest machine tools for him to use.
Nor need you be afraid that your invention will be _appropriated_,
which is a high-toned name for theft, by either the model maker or
his employers to whom you have entrusted your drawings, and for the
following reasons:
(1) Because any hint of such a thing as theft would ruin his business
for all time; (2) because 99 per cent. of all inventions fail to make
money for any one of 99 reasons and (3) because the model maker grows
rich making models for inventors while the latter mostly go broke; and
as far as the employees are concerned we must grant that they are as
honest, or even more so, than the average run of suffering humanity.
Neither are inventions apt to be stolen by patent attorneys for the
reasons cited above but after you have worked out your invention,
built a model and obtained a patent you are then in great danger of
being separated from the fruits of your genius and perseverance by
the professional promoter who makes it his business to finance the
invention and at the same time to feather his own nest; but more
about him a little later.
[Illustration: FIG. 68. SOME USEFUL JEWELERS’ AND MACHINISTS’ TOOLS]
A good way to safeguard yourself at the hands of model makers, if
you have any doubts about them, is to give different model makers
different parts to make and then assemble them yourself. While it takes
considerably longer to build up a model in this secret way still there
is a lot of satisfaction in this method of procedure.
[Illustration: FIG. 69. A SMALL HAND DRILL PRESS]
~The Tools You Need.--~To make a model of any description you need the
usual tools that are the handservants of every jeweler and machinist,
see Fig. 68, and you ought to have a small _drill press_, see Fig. 69,
and a _screw cutting lathe_, as shown in Fig. 70, if you can afford
these machines.
There are two or three tools that nearly everybody knows about and yet
which very few folks know enough about to use them. One of these tools
is the _vernier_ and another is the _micrometer_ and both are used for
_precision_ measurements.
[Illustration: FIG. 70. A FOOT POWER SCREW-CUTTING LATHE]
_The vernier_ is not, strictly speaking, a tool in itself but it is a
device that is applied to _scales_ which makes it possible to measure
small fractions of an inch much more easily and accurately than can be
obtained with the scale alone. The vernier is also used on calipers,
micrometers and other tools and instruments.
The vernier is a short scale which is fitted to and slides along the
edge of a fixed scale as shown in Fig. 71. The fixed scale is divided
into 10ths of an inch and the vernier, which is ⁹/₁₀ inch long, is
divided into 10 spaces.
Suppose now when you measure a part of your model that you move the
vernier over to the right so that the first mark of the vernier and the
first mark of the fixed scale are exactly in a line with each other,
then the vernier will have moved just ¹/₁₀ of a scale division which is
¹/₁₀₀ of an inch.
[Illustration: FIG. 71. A VERNIER FOR ACCURATE MEASUREMENT]
If the record marks of the vernier and of the fixed scale are exactly
even then the vernier will have moved ²/₁₀ of a scale division or ²/₁₀₀
or ¹/₅₀ of an inch, and so on. The fraction of the ¹/₁₀ inch that is
obtained with the vernier is added to the number of inches and the
fractions of an inch of the part which is measured. The vernier gets
its name from Pierre Vernier who invented it in 1631.
_The micrometer_ is a tool, or instrument, which will measure
accurately from 0 to 1 inch in thousandths of an inch. It is one of the
most useful measuring devices that has ever been invented and if you
are to build a model accurately you cannot get along without one. It is
shown in Fig. 72.
There are five parts to a micrometer and these are (a) the _frame_;
(b) the _anvil_; (c) the _spindle_; (d) the _sleeve_ and (e) the
_thimble_. The frame is held in the left hand, the object to be
measured being placed between the anvil and the spindle; the thimble
is turned by the thumb and finger of your right hand and the spindle,
which is fastened to the thimble, turns with it and moves through the
nut in the frame until the end of the spindle touches the object to be
measured.
[Illustration: FIG. 72. A MICROMETER FOR MEASURING THOUSANDTHS OF AN
INCH]
The measurement of the object is shown by the vertical lines on the
spindle and the horizontal lines on the thimble and both of which are
numbered. They are really a form of vernier.
To _read_ the micrometer, that is to find the measurement of an object,
you have only to multiply the number of vertical divisions which you
can see on the sleeve by 25 and to this add the number of divisions on
the bevel of the thimble from the 0 line to the line which coincides
with it, that is, comes even with the long horizontal line on the
sleeve. It is easy to learn to read a micrometer by taking one in your
hands, making a few measurements and following the above instructions.
The _wire gage_ is a circular piece of flat steel a little larger than
a silver dollar and it is used to find the numbers of, and to measure
the sizes of, wires. There are 32 slots cut in the edge each ending in
a hole and numbered from 5 to 36 as shown in Fig. 73.
[Illustration: FIG. 73. A STANDARD WIRE GAGE]
To find the number of a certain sized wire slip the latter into the
slots until you find one into which it will just pass snugly and the
number of the slot will be the number of the wire. On the reverse side
of the gage will be found the sizes of the wire in decimal fractions of
an inch.
[Illustration: FIG. 74. SOME USEFUL STOCK MATERIALS MADE BY AUTOMATIC
MACHINERY]
There are a number of different wire gages but the _American Standard_
or _Brown_ and _Sharpe_, or _B and S_ as it is called for short, is
the one mostly used by machinists in the United States.
Other useful gages are for the measurement of wood and machine screws;
for finding the pitch of screws; for measuring the inside of tubes,
holes, etc., and for measuring the outside of rods, tubes, etc. These
tools and all others used by jewelers and machinists can be bought
wherever tools are sold.
~Buying Materials.--~Many inventors waste time and sacrifice accuracy
in making, or trying to make, wheels, gears, threaded rods, nuts,
binding posts, contact points, switch levers and blades, hard rubber
knobs, handles and other parts.
Now all of these things and hundreds of other parts can be bought
ready made of model makers, gear works and dealers in hardware, model
aeroplanes, electrical and wireless apparatus. And before you begin
a model of any kind you should get catalogues from all of the supply
houses you see advertised. Fig. 74 shows quite a number of parts you
can buy ready made.
~About Making Patterns.--~Very often though you will have to make a
special part out of metal or have it made. Like everything else there
is a _best way_ to do this.
Suppose you need a _standard_ something like that used for a telegraph
sounder, as shown in Fig. 75. To saw and file out a solid piece of
brass would not only take a long time but it would prove a very tedious
job; and this is also true of many other parts you will need in the
course of making your model.
The best way is to make a pattern of wood of the desired part, take
it to a brass, or iron, foundry and have it cast. It is easy then to
smooth it up with a file or to _machine_ it in a lathe, or shaper, and
_lacquer_ it when it will look like a mechanic’s job.
[Illustration: FIG. 75. A STANDARD FOR A TELEGRAPH SOUNDER]
It is nice and easy work to make a _wood pattern_, that is to cut out
of wood the needed part of exactly the size and shape you want the
finished casting to be. The wood for your pattern should be pine or
poplar and thoroughly seasoned. A scroll saw frame will come in handy
for sawing out small patterns.
Where two pieces of wood are to be fastened together a good glue should
be used. After the pattern is built up file out the uneven places
with the kind of files made for scroll-sawyers’ use. When this is done
smooth up the pattern with medium fine sandpaper and finish it with
very fine sandpaper.
Should any holes or cracks show in the pattern after it has been
sandpapered fill them up with _putty_; and, last of all, give the
pattern a couple of coats of _shellac varnish_ or rub _graphite_ into
it all over to keep it from sticking to the mold. Your pattern is now
ready to be cast in metal.
[Illustration: FIG. 76. POURING A MOLD]
A pattern, if it is complicated, should be made by a skilled pattern
maker for it must be made in a certain way so that it will _draw_ from
the mold easily and without injury to the latter and leave it perfectly
smooth.
~Casting in Iron and Brass.--~Somewhere above I said that a pattern
should be the exact size you want the finished casting to be but as a
matter of precise statement iron, brass and nearly all other metals
shrink when they are cooling and so the pattern must be a trifle larger
than the exact size you require and you must also allow for filing and
machining. (See Fig. 76.)
As iron shrinks about ¹/₁₀ of an inch to a foot, brass shrinks ⅕ of
an inch to a foot and steel and aluminum shrink about ¼ inch to the
foot you must allow this much for shrinkage in making your patterns.
Type-metal is an alloy which expands on cooling and this is a useful
thing to know. You will find a formula for making it in _Appendix L_,
and all of the _appendices_ from A to N contain detailed information on
a variety of subjects that should be very helpful when you are making
your model.