On 8/31/2012 10:53 AM, Allan Wechsler wrote:
Don't cut the pieces out of a hollow cylinder. Cut them out of a solid cylinder. I bet George Hart can just print out the pieces for you...
Allan, Yes, and I have a large slide-rule collection, including the "Otis King Pocket Calculator", whose spiral C and D scales would unwind to 66 inches each. So I've thought about making all kinds of slide rules by 3D printing. A cursorless helical slide rule that doesn't "spring" could be designed using a two-color process to make the inner cylinder solid with the scale of a contrasting color, and the outer (hollow) cylinder using a clear material for its background color. (The scale markings could be above the line for one and below the line for the other.) However, the technology is not yet as accurate and inexpensive as one would like for two-color 3D-printing processes. George http://georgehart.com/