Re: [brlcad-users] Making cog wheel in BRL-CAD? - A small correction..
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From: brlcad <br...@ma...> - 2012-05-16 20:37:12
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On May 16, 2012, at 04:08 PM, Csanyi Pal <csa...@gm...> wrote: How can I get a shape in BRL-CAD that has surface DERIVED somehow from an Involute of a circle? http://en.wikipedia.org/wiki/Involute http://en.wikipedia.org/wiki/Gear Here is interesting the head: "Tooth profile". The gear example mentioned earlier at http://brlcad.org/tmp/gear has teeth with an involute of parabola profile [1] [2]. If you check out the gear.g geometry database also included there, you can see how I did it for that specific example. I think I used a couple rpc's intersected and subtraced by rcc's. Perhaps you can extend it for your purpose, using intersecting right circular cylinders (rcc's) instead of right parabolic cylinders (rpc's), or some other primitive [3] if you really need them to be exactly circular. [1a] http://brlcad.org/tmp/gear/mged_tooth_template.jpg [1b] http://brlcad.org/tmp/gear/mged_tooth.jpg results in: [2] http://brlcad.org/tmp/gear/rt_single_tooth.jpg [3] http://brlcad.org/tmp/primitives/Primitives3_grouped_labels.png Cheers! Sean |