Dome Cover for Camp Beaverton

[SBgalaxy]

Camp Beaverton needs a new dome cover. We would really like to buy one and not do a DIY job.

The dome is a 3v 5/8 15.537' 3/4 EMT Dome.
A = 5.416'
B = 6.270'
C = 6.407'
Diameter = 31.075
Height = 18.210
Floor Area = 672.622
Circumference = 97.625

Here is a website that specifies how the material needs to be sewn together...
http://www.domerama.com/calculators/cov ... esic-dome/

Any advice on companies that have produced solid dome covers would be appreciated!

Thanks,
Galaxy

[some seeing eye]

If you get in touch with stretch shapes in SF, they are very experienced in dome covers, though their main business is different.

[BBadger]

http://lmgtfy.com/?q=Dome+Cover

Really. Go look.

What's even more amazing is that one of the places is almost equal distance from San Francisco, where you are, as from Beaverton, OR. It's like you two were made for each other. It'll be like lady and the camp sucking down a noodle and meeting in the middle.

[GreyCoyote]

Just a quick but important point: if you plan on making an all-weather fitted cover for your dome, you need to abandon those "expert" calcs you find on-line. They are both useless and misleading. They are only useful at ONE temperature and ONE humidity. Period. They forget the real-world need to compensate for temperature and humidity, and these factors are far from insignificant.

As a real-world example, consider a 30 foot F4 dome. If you make a nice fitting cover that is carefully measured and cut out of 10 oz shelter duck at 75F and 20% relative humidity, the cover will DESTROY itself when it gets rained on. The cover will shrink nearly 2.5 feet at the base. All those stresses have to go somewhere, so they build up and then shred seams and zippers. Been there. Done that. Ouchies.

FYI: Canvas shrinks when it gets wet. A lot. Depending on the canvas, shrinkage can exceed 4%-5%. In no case is the effect less than 2%. So get a copy of the manufacturers specs for what you are using and engineer the necessary slop into your design. Understand that all canvas (at the thread level) is hydrophyllic... mystical coatings and "pre-shrinkage treatments" be damned.

Design accordingly, and understand the limitations of the fabric you are working with.

[Token]

hydrophyllic


That just sounds so naughty.

Pre-washed Tyvec is pretty stable dimensionally.

[SBgalaxy]

Thanks for the replies!

I appreciate the % change due to environmental factors.

Is there any use in creating the grommet points without having the cover actually over the dome structure? Seems like our grommet points will certainly be off. But our dome pieces won't be set up til playa so I'm not sure how we'd grommet on playa. Seems like a ton of work.

[GreyCoyote]

A well engineered cover does not have grommet points. There will be nylon or poly webbing sewn into loops at reinforced seams. You would anchor to those instead of a grommet.

Grommets can ruin an otherwise good design. They concentrate a lot of stress on a small area. Webbing loops spread the load over a larger area and are essentially unitized into the cover.

FWIW.

[SBgalaxy]

Ok, so here's our current plan... feel free to shoot "holes" in it!

we're gonna buy about 300 sq yds of fuchsia [url]http://www.bigduckcanvas.com/10-oz-duck ... ll/fuchsia[/url]fabric... then we are going to put webbing along 1 ft from each edge and sew it on. then we are going to roll the lengths over the dome and overlap them by 1' on each edge. we will attach the webbing via zip tie to the EMT structure.

advice?

[GreyCoyote]

We need to talk. Check your pm box.

[SBgalaxy]

hi grey coyote, i wanna chat with you soon... i lost my personal phone tonight so i'm handicapped, but i still have a work phone so i'll call you in the next couple days and totally appreciate you reaching out and wanting to share your experience. thanks!
sarah b. <> galaxy