You could try http://metalspinningworkshop.com/forum/upload/index.php
although you do have to register IIRC to post.

Bill wrote:

Hi

I need to build parabolic dishes of different shapes. I think that
spin forming should be the ideal method but I no nothing about that
method. I'm not a metal craftman.

I have some questions about that process.

The material I want to use is either cupper or aluminium. Thickness is
in the order of 20-28 ga.

I don't want to make a mold for every dish because I won't produce
many of each size & shape so it has to be "turned" on air.

Is spinning on air precise enough to produce an exact curve every
time ?

What should be the rotation speed of the machine for let's say a 2-4
feetd dia. dish ?

Can I use a modified small lathe for that or a simple spindle could do
the job ?

Thanks