Re: ATM Need some suggestions on a figure...

[Bill Marriott <btk@pacbell.net>]

AstroJack wrote:
> 
> Hi All,
> 
> I have been working on a 9.75" mirror that is approx. f/6.1.   I currently have two laps, an
> 8" lap and a 5" Star lap.


If it was me, I would make a full size lap.  On anything smaller than
12", thats all you should need, though the other two sub-diameter lap
may come in handy for touch up work.

By the looks of the Ronchi patters, you have a turned down edge, though
not real severe.  Take the full sized lap, tool on top, 1/4 stroke,
center over center, and reduce the turned edge by 50%, then flip over to
mirror on top, continue with a 1/3rd stroke center over center, test
regularily, and things should procede directly to a sphere.

One reporters opinion

Bill Marriott
Chabot Telescope Workshop Instructor
http://www.starlightoptical.com
telescope/optical stuff