[TheForge] Re: Timken Case Hardening was File Making

[Mike Spencer]

> ...spheres are routinely ground out of rocks using a clever
> apparatus.  Take two pieces of pipe, angle them up, maybe 120
> deg. between them.  Leave a space for the rough sphere at the
> vertex.  So rough sphere is held by two pipes.  Now rotate the
> pipes, grinding material at ends of pipes.


I love it. Thanks, Bruce.  With that to go on, I found this:

    Grinding stone spheres is usually done using an arrangement of
    three rotating pipes arranged in a radial pattern, all three pipes
    in a horizontal plane. Separation of the pipes is 120 degrees. The
    stone rides in the region at the center of the pattern, and
    rotates somewhat randomly as the pipes turn. The stone is fed an
    abrasive slurry, and the ends of the pipes do the grinding and
    rotate the stone. The diameter of the pipes and the spacing at the
    center of the pattern determine the size of the sphere. For a
    two-foot diameter sphere you'd probably need eight inch diameter
    pipes. I've seen machinery to make these things, but never that
    size.

But they don't make bearing balls that way, I'll bet.


- Mike

-- 
Michael Spencer                  Nova Scotia, Canada       .~. 
                                                           /V\ 
mspencer at tallships.ca                                     /( )\
http://home.tallships.ca/mspencer/                        ^^-^^