On Sat, 9 Apr 2011 00:32:29 -0400, "Ed Huntress"
wrote:


"Tim Wescott" wrote in message
...
On Fri, 08 Apr 2011 23:16:17 -0400, Spehro Pefhany wrote:

On Fri, 08 Apr 2011 23:08:55 -0400, Spehro Pefhany
wrote:

On Fri, 08 Apr 2011 21:38:25 -0500, the renowned Tim Wescott
wrote:

I want to make a bunch of identical molds, for 3/4" diameter model
airplane wheels.

I'm envisioning a tool that's 3/8" across, that I just sharpen up, grit
my teeth, and push into a spinning piece of aluminum to make my desired
profile.

Is this a sensible thing to consider? Is there some other way (short
of CNC machining) to easily duplicate cavities in the ends of a bunch
of aluminum tubes?

Hobbing?

P.S. Not the gear-making process, this one:

http://tinyurl.com/hobbing

Well, the cavity is cylindrically symmetrical, so I'm not sure that
"hobbing" is the right term.

It's probably been a screw machine operation since 1920, or at least some
sort of tracing operation.

Sigh -- I'm always behind the curve.

I must be dull tonight, but I can't visualize what you're doing. Are you
talking about some kind of forming in the axis of a spinning tube, or
turning the outside diameter to a profile?

Like ED, I'm not picturing your cut. That said, form tools up to 3/8
wide are no trouble on a lathe. For example, I cut a V groove in a
pulley for a V belt all the time.

This assumes your lathe is rigid enough for the cut.

Karl