dome tubing size

ellorbito · Post by **ellorbito** » Thu Apr 23, 2009 5:40 pm

I plan on building a dome this year and was wondering if 1/2" electrical conduit is strong enough for the occasional dust storm. The dome will only be about 17 feet in diameter. Any input will be met with gracious and heartfelt thanks. Plus good mojo.

ygmir · Post by **ygmir** » Thu Apr 23, 2009 5:43 pm

I'd think not......seems they're made from much stronger stuff, it probably also depends on how big the triangles are and bracing......but, I'm sure an expert will chime in soon.........

motskyroonmatick · Post by **motskyroonmatick** » Thu Apr 23, 2009 9:03 pm

From other posts here I would recommend at least 3/4" conduit.

robotland · Post by **robotland** » Fri Apr 24, 2009 4:54 am

I'll second that! I'm in the process of finishing my art fair display dome, which I'm making from 1/2" because I have almost enough salvage tubing around to finish it without expense....But even though it's designed for a non-windload covering and will never be climbed on (unless an art patron REALLY loses track of their kid!) to use the 1/2" stuff goes against most of my instincts. And this dome is only 10' in diameter.
The effort required to make it from 3/4" instead is negligible- It's ONLY the cost factor that compels me. If you plan to use the dome in the future, make it from 3/4". It'll last forever(-ish).
EXCEPTION: If you want to build a higher frequency dome, with MORE struts that are all shorter and therefore carry less load per strut, then maybe you could get away with 1/2". The tolerances are tighter, the construction is more complicated, and you'd be hauling more weight in struts than you would be by just using bigger EMT.

stargeezer · Post by **stargeezer** » Sat Apr 25, 2009 8:15 pm

If you are starting with full length sticks of conduit, 17 feet in diameter is a very inefficient size to build, you will have a lot of waste. If you would like some help to minimize waste, PM me with a size and frequency range that you would like, and I will do the calculations to waste as little of the conduit as possible.

robotland · Post by **robotland** » Sun Apr 26, 2009 5:10 am

Actually, if it's a 2V dome then the optimum size is around 19', if memory serves.

*digging in pile of notes for strut factors*

Rats. Can't find it.....

...I'll get back to you on that one.