BUILDING A CORLISS

GEORGE HENRY CORLISS

GEORGE HENRY CORLISS

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While restoring a Kingerey steam engine, I remembered an event back in 1926, when I was a young boy. I recall watching the operation of a Corliss engine in a creamery in Grand Forks, North Dakota. I will never forget the slow, positive strokes of the crosshead and the quick cut-off actions of the dash pots!

While the small Kingerey did not belong to me, I decided to build some sort of a small stationary steam engine!

Living on a small city lot with only a single-stall garage, I was prevented from collection and restoration of actual size engines of any kind, even the small hopper-cooled gasoline engines, which intrigued me very much.

The decision was to build a miniature model of the 'king of them all' the Corliss!

I first decided to learn about the history of the engine. I read some information on George Corliss himself, and studied Audel's book on the Corliss engines. It was interesting to find out that George H. Corliss, although possessing inventive ability, was actually a harness maker. He was born on June 2,1817, in Easton, New York, and died in Providence, Rhode Island, on February 21, 1888. Mr. Corliss was not fitted by any special education for his great work of taking the steam engine from where it was left by the immortal Watt, and bringing it to its present high state of perfection. He never saw the inside of a machine shop until he was 24 years of age. He attended an ordinary village school until he was 14. Working on leather harnesses resulted in the invention of a harness sewing machine which long preceded the famous sewing machine invented by the Howe brothers.

George Henry Corliss first came to Providence in 1844 to complete an invention of his for sewing harness leather. He took his work to the steam engine works of Fairbanks Bancroft & Co. He showed such adaptability as an inventor and draftsman, that he was requested by the firm to come and work for them and he abandoned the harness sewing machine.

A professor in Providence, became interested in Corliss' talents and gave him some calculations on the expansive action of steam which had been made in 1830. Corliss gave his entire attention to the steam engine and invented a valve gear for using steam expansively. The great success of this invention made him famous. He designed his first engine using rotary valves in 1850. Essentially, the expansion of steam in his engine was cut off and varied and controlled by the governor. The degree of expansion, on a Corliss engine, is automatically changed to suit the load and speed conditions. In 1856 he established the Corliss Steam Engine Co. in Providence, Rhode Island, which at once came into prominence.

Corliss, like most inventors, had to force his invention on an unwilling public. He had to assume all of the responsibility, and in many in-stances take pay in what he could save the customer in fuel. In the end, this proved fortunate for him because in most cases, he received far in excess of the price he had placed on the machine. At the time Corliss was selling his automatic machines for what he could save, the United States Government was spending money on experiments to show that there was no economy in using steam expansively.

Many Corliss engines were used to manufacture electricity, especially by large manufacturing firms who chose to make their own power. Some were also used in sugar cane mills and may even be in operation today. Restored Corliss engines can be seen in various museums today; some examples are in Dayton, Ohio; Greenwich, Rhode Island; Henry Ford Museum in Detroit; Rollag, Minnesota; Pawnee, Oklahoma, and the Smithsonian Institution. These are just a few that escaped the cutting torch!

The extreme weight and slow RPM of these engines were distinct disadvantages and eventually the high speed steam engines, diesel engines and the steam turbines took over. As an example, I recently had the opportunity of visiting the power section of the Henry Ford Museum in Detroit. Some of the Corliss engines on display are enormous. I measured one flywheel 25 feet in diameter, one lhalf of its diameter in a pit in the floor and the face of this wheel 3 feet in width.

How does one start making a model? First of all an order is placed for a complete set of blueprints. After receiving them, make a thorough study of each part and make absolutely sure that your machine shop can handle each size. At this time it is also a good idea to make a list of the materials, metal barstock and small parts, such as nuts and bolts; there are parts such as the flywheel, crankcase, pillow block and the engine bed, which should be purchased as raw castings. These will be machined later. There are 14 large-size drawings so it's also a good idea to make an index so as to more quickly be able to refer to various details and parts. It will also be necessary to buy some of the left-hand taps and dies, called for in the drawings. These will be used in the fabrication of the various turnbuckles used to adjust the various valve rods during the timing of the engine. Procure a set of bevel gears for the governor.

Probably the most critical machining will occur in the machining of the rotary valves, four of them, and the four pockets in the cylinder block which will receive them. These play an important part in the timing of the engine and it is very important that slots be machined as specified and located to the dimensions. In my case, the valves were made a couple of thousandths oversize to cause an interference fit. Then I rung-fit each one into its respective pocket, doing this in the lathe and using a generous amount of oil. The pockets in the block were reamed.

This engine is just about the right size for easy handling and yet small enough so as not to present unusual problems of construction. In my case, I own a 9' South Bend lathe, a drill press and the regular variety of inspection tools and gauges. Although a power hacksaw and a belt sander come in very handy, they are not absolutely necessary.

To machine the cylinder, dress the end surfaces of the block, perfectly flat. Locate the center of the bore and remove most of the metal with drills. The material is cast iron. To finish the bore, which is 1' dia. by 3' long, mount in a chuck and use boring tools, or mount on the lathe saddle and use a boring bar between centers. The tools should be sharp and set the lathe power feed at its lowest rate of advance. Open the bore a little at a time. When you get up to the right diameter, traverse back and forth several times at the same setting. This will produce a very smooth bore, but avoid any chatter during this operation. Follow this with a honing operation.

I would like to invite all of you miniature model engineers and makersto submit your contributions as well as any questions or problems, which you think would fit this magazine. Good photographs of your building efforts are very welcome. We will be anxious to hear from you.