I posed the question to retired friend who was a miller among other things.
He suggested putting a fly-cutter with a radius of swing equal to that
of the required hemisphere, into a vertical mill. Mount a rotary table
with its axis parallel to the machine bed and aligned with the vertical
of the fly-cutter. Attach the work-piece to the rotary table. Apply feed
with the mill table horizontal feed and rotate the rotary table to shape
Thanks all. Perhaps I should have been clearer - I need a fairly perfect
hemisphere - it's for a mirror.
I think this method comes closest - but I will probably buy a large
ball-bearing and use it as a mould.
-- Peter Fairbrother
On 21/05/16 15:06, Dragon wrote:
When I worked for a bearing manufacture as a tool and die maker we lathe
turned the halves, weld, heat treat, chrome and then sent the spheres
for roll grinding and then removed as needed to make it the hemisphere.
The ones I did where like 5 inch outside, 4.5 inch inside diameter for
display items back in the 70's. Now I'm sure the inside would be done by
cnc machining on case hardened balls?
What are your plans?
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