Back to Home

ATM Forum Message

Forums: Atm · Astrophotography · Blackholes · Blackholes2 · CCD · Celestron · Domes · Education
Eyepieces · Meade · Misc. · God and Science · SETI · Software · UFO · XEphem
RSS Button

Home | Discussion Forums | Amateur Telescope Making | Post
Login

Be the first pioneers to continue the Astronomy Discussions at our new Astronomy meeting place...
The Space and Astronomy Agora
Are You Sure?

Forum List | Follow Ups | Post Message | Back to Thread Topics | In Response To
Posted by Rick Crockett on September 17, 2000 17:26:41 UTC

Hi Tom,

I get a compression load in excess of 35,000lbs/ćin and that assumes the circumfrence taking an equal load which we know it doesn`t. A simple safety factor of 2x because the off axial nature transfers the compression to one side of a circle would then give 70,000lb or about four times more than you were expecting.

We always wish for a static load but just don`t get it in the live load world. From first hand experience I know the 6" sch40 steel pipe even filled with rebar and concrete will be unsatisfactory. A friend used a 10` piece 4` into the 1yd concrete footing. He is an architechtural engineer. The 6" refractor would yield to gentle breezes and wobble when one adjusted focus, align the finder, etc. Massive and strong is not always enough. His remedy was to bias the load.

I am not sure about the 1.7 cycle vibration rate, sounds a bit low unless that includes the 850lb load. Either way the fact that it is sub-audible does not mean it is neglible. Our California Earthquake are sub-audible but the din from crashing objects can be quite loud.

I think your discussions are good though as it points to the fact that one should include the various elements. Only one thing I might differ on and that is I would buy rebar bolts or J-Bolts. Rebar is a very soft metal and pipe threads are meant to seal and are not strong. It would be useful to see your calculations. Very interesting.

Cheers and Clear Skies,
-Rick

Follow Ups:

Login to Post
Additional Information
Google
 
Web www.astronomy.net
DayNightLine
About Astronomy Net | Advertise on Astronomy Net | Contact & Comments | Privacy Policy
Unless otherwise specified, web site content Copyright 1994-2020 John Huggins All Rights Reserved
Forum posts are Copyright their authors as specified in the heading above the post.
"dbHTML," "AstroGuide," "ASTRONOMY.NET" & "VA.NET"
are trademarks of John Huggins