Image of the day

Captured by
Roberto Garofalo

North America & Pelican Maped color

My Account

New to Astromart?

Register an account...

Need Help?

Re: 18" starstructure solid edge cell part 5

Started by Preston E, 01/14/2004 09:03AM
Posted 01/14/2004 09:03AM Opening Post
Micheal, Very nice overall design. You might want to look at "Reflecting Telescope Optics II" by R N Wilson pages 259-272 have quite an indepth and current discussion on edge support and the requirements.

I believe that your current setup is similar to Schwesinger's case "e" page 265 where the support is discribed as followssadV-support: The astigmatic mode disappears if the angle 2e=90 degree. Thus the right-angled V-support is almost optimum and gives a big improvement over a pure edge support).

However, I would look closely at you supports contact points close to the mirrors surface. From the research presented in the above referance, it concludes that support should come from the center of the edge in mirrors with f ratios greater than about 3.

Very nice workmanship...Keep it up.

Best Regards Preston
Posted 01/14/2004 04:54PM #1
Micheal,
that sure seems to be good numbers to me. .005" is not much shift at all.
I wish I had that little sag in my scope. I can see some movement in the laser beam when I move from horizon to zenith. maybe 1/16-3/32" but more than .005" that is for sure. I think it is the tubes that are flexing with my scope.
Floyd

[SIZE="Large"][/SIZE][COLOR="Blue"][/COLOR] Floyd Blue grin
Amateur Imager
Posted 01/14/2004 05:03PM #2
Good Evening Micheal...I use to have the same ideals...

But learned that asking questions of others, more importantly those that are in the field in the know, will likely reduce by a very great amount of time my investigations...and ...$$$$$

They in general like to answer well founded questions...and reading the latest in telescope technology cannot hurt...

Granted the book is looking at 1 meter plus size scopes, and also looking the the 8.2 meter to 10 meter designs.

But this does relate to out hobby...

JMHO

Best Regards Preston
Posted 01/14/2004 05:17PM #3
Micheal Great test on the physical movement...our mirror lateral movement is limited to .0005", but we are working with cored mirrors and astatic axial support

But again, with optics in place your lateral supports are very likely to cause a deformation in the mirrors figure that will be seen when lowered past vertical by placing a load on the front edge of the mirror...I'll leave at that...

Good Viewing and Best Regards for some fine construction details...

Preston
Posted 01/14/2004 06:34PM #4
A dial guage works great.

A little geometry compass works, too. K.I.S.S.