Re: ATM Input on "cannon ball pier" from newbie sought ...

["Bob May" <bobmay@nethere.com>]

There's many ways of making that disk edge spherical.
First is to cut it to an approximate radius and finish by grinding just like
you do glass.  Same process and same methods work just fine with aluminum,
etc. as it does with glass.
Second is to do a radius bar setup on the lathe.  With a radius that short,
an actual radius bar can be used rather than the double bar setup.
Third is to make up a tool to actually do the cut and do a single plunge cut
on the edge.
Other methods can be done but these are the most accurate methods that are
readily done.
Bob May
http://nav.to/bobmay
bobmay@nethere.com
NEW! http://bobmay.astronomy.net