In this thread I will present a short description of my construction of a 1/4 scale model of the Anzani Fan Type engine of 1909 with images of the build process. I will also provide the working drawings.
Several years ago my neighbor was moving away and I happened to see a Benchmaster mill in the back of his garage. I had never seen such a cute little machine before and decided on the spot that I had to have it. We dragged it up to my house and I was started on the path to being a home shop machinist. Eventually I acquired a 9" Southbend lathe and then a 10" Logan and some used tooling from various swap meets. My first engine project was the Crusader 60 engine from an article by George Genevaro in the Home Shop Machnist magazine from 2005.
After getting the Crusader 60 running I was ready to attack a more ambitious project and I began researching the Anzani Fan type engine on the internet. I found drawings in the Encyclopedia Britannica from 1919 and spent a year or so doing research on the web and developing my drawings from the Brittanica drawing. I first used a tool called scan2cad to convert the image to a dxf file. This needed a lot of hand work to get rid of excessive vectors generated by noise in the raster image. Eventually I turned to Draftsight to trace the Britania drawings. Over time I produced about a dozen pages of drawings of individual parts with 1/4 scale imperial dimensions. I found other cleaner and finer resolution versions of the same drawing in other sources to improve my drawings.
I found a lot of images on the web. One site had photos of all the engine parts and I first thought I might scale these. I found that scaling from photos is more like freehand drawing than drafting. Plus, the images were distorted for some reason so nothing round looked round. Still these images have good information. Other sites had photos people had taken in museums. I contacted everyone I could and they were usually very helpful. One guy in particular, Carl Gootzen, of Antwerp Belgium has actually worked on one of these engines at the Stampe Museum where he volunteers. Carl visited the Paris Air and Space Museum to get more information for me. Another guy in England sent me photos and sketches of the compression release mechanism, the carburetor and the intake valve assembly. I found a guy who wrote a book about finding one of these engines hanging with the harnesses in an old barn in France and he helped with the exhaust tappet dimensions. All together I accumulated about 750 files in a gigabyte of data. Once I learned the name of the carburetor manufacturer, I found the US patent for the carburetor and also drawings and descriptions in some old books.
From the dates on my emails and files I see that I acquired the first web data in June, 2008 and made the first machine cut in November, 2010. At that time, even though the drawings weren't completed, I thought that if I didn't actually buy some material and start cutting, I would never build this engine.
I started work on the engine with the cylinders because they seemed to be the biggest challenge. They have fine fins, integral heads and an angled exhaust port. I thought that if I could make them, the rest of the work would be straight forward. So, I began by roughing out the exterior shape from a bar of 12l14 steel. It was good that I had lots of material since it took seven tries to get the three roughed out cylinders.
The lower portion of the cylinder and the bore were turned on the lathe in a conventional manner. My experience with the Genevro Crusader 60 informed me about useful fixtures to hold the cylinder in the lathe and mill setups. As you will see I made several tools, including a 1/2-40 tap for the exhaust tappet guide. The exhaust port was bored with a D-bit of the correct diameter and the exterior shape of the cylinder was formed by stepping around with a single point tool moving vertically at each step. I wrote a simple program to calculate offsets to step around the circumference of the cylinder shape. The tool cutter radius was set to provide the proper exterior shape for the concave curves.
The combustion chamber was formed and the heads were made to be silver soldered in place later. The heads were held in an aluminum fixture and the exterior top profile turned in the lathe. The opening for the intake valve cage was threaded 1/2"-40 in the lathe and the boss around it and the center access plug was formed.
On the cylinder, the little boss around the exhaust valve guide was formed in the lathe with a throughly disgusting tool that was ground for clearance as the flange rotated around it. This boss centers and retains the exhaust valve spring.
Finally, a fly-cutter was made of the proper thickness to cut the spaces between the fins and the fins were cut by stepping around the cylinders. This cutter was very thin and fortunately I only broke one while cutting the three cylinders. The 12l14 is excellent material for this kind of work and now this began to look like a cylinder.