pic: Dented IFI Wheel

[Richard Wallace]

The designer of these wheels visited St. Louis back in December, serving as a technical advisor for our FVC demonstration event. He left me a sample 6 inch x 1.5 inch IFI wheel.

A few minutes ago I took that sample down to the CMM that we use to check parts here at Emerson's motor tech center. The results showed that the six hole pattern intended for mounting sprockets is concentric to the bearing hole within 0.004".

Each of the sprocket mount holes was 0.197-0.198 diameter (very nearly 5 millimeters). I'd conclude that the ideal sprocket screw size would be #10, or M5 if you wanted to use metric fasteners. Off center sprocket mounting could result from using smaller fasteners such as #8.

Of course, my CMM results are from a single sample. Close inspection of the holes indicates to me that they were punched, not drilled or bored; from this I guess that the sample was made using the punch tool that IFI subsequently used to make production parts.