On 7/28/2010 6:51 AM, Ignoramus6705 wrote:

I am pretty sure it is a front sprocket. Whatever you can find out,
will be most gratefully appreciated.

A year and model would be of great help. And from a previous reply,
while you might be able to generate the general angle by interpolation,
you will in fact, have a series of concentric rings of narrow contact
formed by the cusps of the successive passes. What is likely to happen
if this is ridden much, is the high points will wear or deform,
affecting the fit of the sprocket to the shaft. Any movement at all will
result in fretting and wear of both parts. You are dealing with a
combination of cusp height between milling passes, and the milled finish
itself, which might look smooth to the eye, but is really rough at the
microscopic level. All tapered sprocket bores I've ever seen are ground,
and generally it is the friction of two finely matched surfaces that
transmits the torque. Reduce the surface area in contact due to surface
roughness, and you reduce the torque that can be handled. If however,
this sprocket has a key, that would go a -long- way toward helping your
approach! I don't imagine a 1920's era Indian is going to be flogged,
but with the scarcity and expense of parts, it would be wise to try and
insure the best possible match.

A step over of .001 would improve things quite a bit. But then there's
the issue of just how round a hole can you interpolate on that thing...

I'm certainly not trying to knock what you're doing, just that I foresee
potential problems and that's coming from my combined experience with
machining and motorcycles.


Jon