Re: [ATM] Polishing / Figuring Simulator

["James Lerch" <jlerch1@tampabay.rr.com>]

----- Original Message ----- 
From: "Jerry" <wa4guu@verizon.net>

> Why do you think that figuring is guess work? If you have learned from your
> experience it is like driving home from work. Along the way you look and see
> where you are and when you get to the turns you make them. It is
> predictable.

In some cases I agree, especially with hand figuring on "normal" Newtonian sized 
ATM primaries.  The 8" F/8 bino mirrors (my first optics) figuring was as you 
described, and almost a non event. Several 10 inch F/5 to F/6 also were very 
intuitive.  However when the first 12.5" F/4.5 found itself on the machine, 
intuition went south.

For me, machine figuring was / is an adventure, often starting with large 
quantities of frustration if working on an unfamiliar size or F-ratio.  The 16" 
F/4.5 responded differently than the 14" F/4.5, and the 14" responded 
differently than the 12.5".  In each case I did "find my way home" but the word 
"Predictable" isn't something I'd use to describe the process I observed!

I once tried fabricating an 11" F/7 with a conic constant of -13 (minus 
thirteen), I couldn't do it.  I could get a conic of around -5, then I'd start 
changing the RoC and stop adding correction..  If curious, this was going to be 
the primary for a two mirror Schwarzschild F/3 OTA.

My next project is going to be a Corrected DK Cass, with an F/3.5 primary (the 
fastest f-ratio I can test with my Fizeau interferometer).  I anticipate 
figuring the primary to be an "interesting" challenge.  It would be nice if I 
had a working simulator to at least give me a rough idea on what lap variables 
to implement during the guess work phase of figuring.

Take Care,
James Lerch
http://lerch.no-ip.com/atm (My telescope construction,testing, and coating site)
http://lerch.no-ip.com/ChangFa_Gen (My 15KW generator project)



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