His name is Jerry Kieffer. He is not a professional machinist, but a retired field representative for a Wisconsin power company who turned his home shop into the finest and smallest examples of model engineering to be found anywhere in the world. He has been building a number of incredible projects, including two miniature Harley Davidson motorcycles, a 1/8 scale John Deere tractor, several other steam and gas engines, clocks, etc. He owns a 1947 Knucklehead Harley Davidson that he completely restored. So he measured each and every part of the his bike to make the scaled down parts for his model. Yes, the full motorcycle is in process with the motor running and all the systems working.
He wants this tiny engine to start with a kick starter just like the real engine. He also wants the gearbox to function and the speedometer to work. And if you are not still not blown away by the talent and dedication of Jerry Kieffer, think about what is involved in this -lifelong? – project. Of course, 1/8 scale means 8 times smaller, but keep in mind that when reducing in size, the part size goes down as a function of the cube root of the volume, not as a simple linear reduction.
For example, the volume of a part at 1/2 size is actually 1/2 the length times 1/2 the width times 1/2 the height. That means the 1/2 size version of a 1″ cube would be a cube .5 x .5 x .5 or .125 cubic inches—1/8 of a cubic inch. A1/8 size model of a 1 inch cube is .125 x .125 x .125 which equals .00195, or less than 2 thousands of a cubic inch! For example, the smallest bolts on the factory Harley Knucklehead engine were 1/4-20 size, which translated at the model size are bolts smaller than ten thousandths of an inch in diameter with hundreds of threads per inch at 1/30th scale! There was nowhere to go to find threaded tiny parts that small. Giving up? Of course, no. After many efforts at trials and errors Jerry developed techniques of making extremely small taps and dies and succeeded at making tiny hex head nuts and bolts. And jerry states that “Making them is easy. It was figuring out how to make them that was hard.” At least, when his project is completed and running, I hope that Harley-Davidson will honor him with a permanent exhibition spot at its Milwaukee Museum. Jerry Kieffer.