Re: ATM turning long radii

[andydtg@alpha1.phoenix.net]

Michael Spooner wrote,

>Never did get the center ground down and attempts to use the lathe 
>were a silly bunch of flat steps because I haven't a clue how to
>turn a large radius.  I have seen radius turners for very short 
>radii but nothing that could work here.
>
>How does one do this?

The original ATM books show a linkage which allows long radii to be
cut on a lathe. If you don't have the books I can scan the relevant page
and send it to you as an e-mail attachment. It's a bit too complex
for ascii art & difficult to describe.

Another way, if you have a vertical milling machine and a rotary table,
is to use a flycutter set at an angle to the rotary table's axis
and rotate the stock. This is basically how curves are generated on
lenses, using a diamond cup wheel instead of a fly cutter. I've used
this method successfully to make mirror mounts which allow tilting
the mirror without displacing it's optical axis. Convex and concave
surfaces can be made this way.




Andy Saulietis / DTG Alt-Az-Fp Drive Systems
12617 Harriet Ln
Santa Fe, TX 77510 USA
409-925-8854 Voice/Fax