BUILDING Scale Models

By Staff
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1362 Valley Road Oshkosh, Wisconsin 54904

I would like to share with others my hobby of building scale
models. I have always been interested in the Rumely Oil Pull
tractor but rather than trying to obtain and restore one I decided
to build a half scale model. At first I was going to use one of my
antique gas engines for the motor but then changed my mind and
built the whole thing from scratch.

The first step was to locate a full size tractor. I was
fortunate enough to find one, a 1920 or 1921 Model 20-40 on a farm
about ten miles from my home. My wife and I made many trips to this
form, measuring and sketching every part we could get at. We also
took numerous pictures. At one of the old time engine shows I found
a Rumely book showing the breakdown of the engine, transmission,
drive gears and running gears. This gave me much needed internal
specifications and saved many trips back to the ‘parent’
tractor.

The first thing built was of course the framework and then the
wheels. I had to get assistance for these. I had the metal for the
wheel rims rolled at a sheet metal shop. I then made up the hubs
and spokes and welded them all together.

To build the radiator it was necessary to deviate a little from
the authentic construction. I finally settled on conduit for the
cooling tubes and used 81 to build the radiator half scale. It
works with the same efficiency as the original.

Looking for a flywheel I found that one of my old gas engines
had one that was just the right size. Not wanting to rob that
engine I sent the flywheel to my brother John in Minneapolis who
has a machine shop. He had a duplicate cast for me and did the
necessary machining for use on the Rumely.

Some years back, at an auction, I had purchased for one dollar
two old wheels with drive gears attached. These turned out to be
the exact size I needed for the rear wheel drive gears.

The last and most difficult part of the project was the engine.
I built the block, crankshaft, cam shaft and heads myself. I found
that the connecting rods, piston and sleeve assembly, cam drive
gear and governor from a 1936 Case tractor were half the size of
the Rumely and so I could use them in my engine. I was able to use
a four cylinder Jeep down draft carburetor but had to build the oil
pump myself in order to get one that conformed to the needs of my
engine.

This whole project took me one and one-half years to complete.
The building was done at my commercial garage and many friends and
customers watched the progress with interest and brought me things
I might use or told me where I might obtain others.

Opinions were divided whether it would actually run. Of course
everything wasn’t right at first and I had to do some revamping
once it was running but I am thrilled to say it now runs
beautifully and looks and sounds like the early 1900s with the
traditional ‘poomp, poomp, poomp’ and the exhaust coming
out of the stack.

Five years ago I built a scale model five inches to the foot of
a 28 inch Case threshing machine which does an excellent job of
threshing. Previously I had powered it with one of my home built
garden tractors but this year it will be one powered with the
Rumely Oil Pull. My wife and I hope to take them to many of the old
time threshing shows throughout Wisconsin and possibly into
Minnesota in the summer of 1986.

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