Little Sam Update
The Little Samson continues to develop its unique character. As you can see from the photos, all the secondary castings are here except for the main valve box.
Castings are designed with "chucking pieces" attached. These chucking pieces are very important, providing an easy way to hold the casting while machining. When developing initial patterns, machine processes must be thought out in advance and necessary chucking pieces designed integrally with the pattern.
It is easy to make mistakes in pattern making. I had no idea the ignition cam pattern was backwards until I machined it and set it in place on the engine! I simply fabricated one up and silver soldered it together. It is actually better than a casting.
For those familiar with the early N Samsons, the flyball governor draws the eye and instantly becomes the focal point. It is beauty and function combined in a delicate yet sturdy design.
The Little Samson governor is cast iron and steel, replicating the original materials used in full-size practice. The main driveshaft runs in a babbitted bearing. A pinch bolt secures the governor assembly to the top gland, which carries the speed control assembly.
After fitting all the little bits and pieces together, I am very pleased with the end result. It spins quietly with the fingers while the balls do that graceful "dance of the radius." The little bobbin valve moves up and down throttling an imaginary mixture of explosive gas. It will soon be put to work!
The governor assembly has been the most difficult component thus far. It is a very fiddly business to fit all these little pieces together, but the patterns proved to be correct, as well as the little Boston miter gears. A special ball jig was made to measure the hang and other factors involved in producing two identical ball weights. It was a real process to produce this little gem.
The photos show some bits and pieces already made or in the process of being made. I am still waiting for the foundry to produce my main valve box. It is very important because almost every piece of valve gear locates off this box. I am anxious to have it cast, but the wait has resulted in taking more time and care in the finishing of the other pieces.
So far this Little Samson has managed to involve every skill I've ever acquired, plus created some I didn't even realize I possessed! One of the things I find myself doing is studying every casting I see and trying to understand how it was poured. It leaves me with a great respect for the wonderful castings we see in our engines. The pattern makers and foundrymen of old were more highly skilled than we can ever understand. Their's is indeed a lost art. We will never achieve again the marvelous works of art and intricate moldings that our forefathers achieved. It is sad in a way, but also wonderful that so many of the pieces survived for us to wonder at and admire. - Lester Bowman
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