Ignoramus6705 wrote:

On 2010-07-28, Jon Anderson wrote:
On 7/28/2010 3:41 AM, Lloyd E. Sponenburgh wrote:

My first two questions would be: "Is the hub conical simply as a
casting/forging expediency?", and (if it's tapered on the i.d.) "could I
cut that with a tapered reamer instead of milling the hole?"


I've never seen a rear sprocket that had a tapered seat, but never know
with vintage stuff. However have seen dirt bikes with tapered
countershaft instead of splines. These are very precise tapers, and I
question the ability of a mill to interpolate a sufficiently accurate
taper just in terms of the angle, let alone getting a surface finish
that will do the job. Husqvarna dirt bikes of the 70's for one, used
ground tapers. These could be a real bitch to remove.

Is Iggy just roughing out the taper so it can be more easily ground? Or
trying to generate a finished and functional taper? If it's for
something really rare and not to be ridden or ridden only very gently on
rare occasion, maybe an interpolated taper might hold up. But it would
be wise to consider the possibility of munging up the shaft taper on a
part that might be very hard to come by.

I am assuming front sprocket here as again, have never seen a rear
sprocket seating on a taper.

If the taper can be accurately measured, it can be accurately milled
with a ball end mill. I am not really pretending that I know what I am
doing, but to me the big issue is whether we can measure the taper
with the required degree of accuracy.

We can always test the fit with Prussian blue or something.

i

The surface finish of tapered fittings is rather critical. Would you try
to ball mill and R8 collet? Material and heat treat also come into play
for something like this.