On Sun, 04 Jun 2000 19:55:29 -0700, Loial Raven <Loi### [at] telusnet> wrote:

>Ok... i just read the thread on looking for gears... i'll let my gear
>stuff out :)
>
>I've been working on this for quite a while, it's still not finished,
>and it won't be for quite a while yet. Right now i'm working on bevel
>gears, as well as looking at making helical gears and helical bevels...
>

Loial,

I think several of us in the POV community have had a go at gears.  Marc
Schimmler and I have both posted macros for the generation of accurate involute
gears.   Marc's gears are specified using the module of the gear and mine use
the diametral pitch.

Your macro seems to use the same technique as mine - a linear spline prism to
define the tooth.  In my case I calculate an array of points on the tooth
profile and then plug them into the prism, whilst you calculate them when
defining the prism.  For the bevel gear I used a similar technique, but with a
prism with a conic sweep.

I did a comparitive test and rendered a 50 tooth gear of similar size using both
your macro and mine, and yours took about 3.6 times as long as mine. I can't see
why this should be, but perhaps you can find it.

My macros and example programs for both types of gears are available for
download on my website www.hamiltonite.com (The downloads also include flc
animations.)

Both Marc's macros and mine are intended to be simple to use.  In my case the
pressure angle is assumed to be 20 degrees, a widely adopted engineering
standard.  In the case of my spur gear macro, the user only needs to give the
diametral pitch (dp), the number of teeth and the face width. The bevel gear
macro is equally simple to use.

I look forward to seeing your helical gears and spiral bevels.

David

dav### [at] hamiltonitecom
http://www.hamiltonite.com/

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