Re: tiny rivet heads

>From: patv@...
>
>I'm into model railroading and I've been trying to make HO scale parts
>using automated techniques. Unlike most folks, I'm not as concerned about
>power as I am about the ability to machine details. For example, a 1"
>dome representing a rivet in HO scale is 0.0115" in diameter and 0.0057"
>high. Spacing in between these may go as close as a scale 1.5" centers or
>only 0.0057" gap between domes. As you can see, this would mean I need
>some very tiny end and ball mills.

Interestingly, I have some of the same needs in my clockmaking work. The
beading on clock bezels is the same sort of thing, and the "beads" almost
touch. I was planning to make a special form cutter, where the cutter
would have an internal radius to machine the raised "hump" It would be
easier to form the cutter if it was a single flute, and with soft metals
(brass in my case) it should work.

You could also machine a negative form, making the rivit heads with a ball
mill, using it as a form for a lost wax pattern. The old clockmakers had
special form knurls, not only for beads, but for crosshatching, acanthus
leaves, ad infinitum, which were rolled onto a soft cast blank.

David M. Munro