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01/16/2010, 04:54 PM | #1 |
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DIY 60 gallon stand - Do I need a center brace?
Does this stand need a center brace? The top brace is 2X6, everything else is 2X3. Ive read that the maximum deflection that silicon, in a tank, can take is 1/8" before it starts to fall apart. I think it is reasonable to assume that the best case scenario is zero deflection. The total weight of the tank, water, live rock, canopy, lights + for my setup is about 700 lbs. Since there are two horizontal beams each beam will support 700/2 = 350 lbs loaded uniformly. For calculations lets assume its uniform loading. deflection for: (2X4) Horizontal top struts - .038" (2X6) Horizontal top struts - .01" I see a lot of stands on reefcentral that have no center brace with longer spans between the vertical end struts. If failure occurs at 1/8" deflection (2x4)'s provide a 3x factor of safety while (2x6) provide a 12x FOS. I dont think at all its over engineering to use (2x6)'s. I feel uneasy that the horizontal members will constantly be deflected due to the weight of the tank. With constant deflection the silicone seams will also be in a constantly loaded/unnatural state. This may not be too bad, because the enormous pressure of water will load the silicon seams. But too much is no good. My question is not how much is too much, but is designing a stand knowing that it will deflect smart? I would really like to not have a center brace so I can have a deeper sump/refugium. Any input?? |
01/16/2010, 05:27 PM | #2 |
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No you do not need a center brace on that stand. 2x4s will be fine, but if you do use the 2x6 you will not have any problem. There is a great thread on here about building your own stand created by rocketengineer, that if you read through the whole thing will give you lots of info on the engineering.
Kim
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Proud Member of the Idaho Marine Aquarium Society America will only be the Land of the Free as long as it is the Home of the Brave. Current Tank Info: AGA 180gallon tank, VHO/MH lighting, DSB, calcium reactor, Also a 7 Gallon Nano softy tank, and a 32 gallon cube |
01/16/2010, 10:41 PM | #3 | |
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01/16/2010, 10:42 PM | #4 |
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This is the stand with 1/2" oak skin with a center brace built into the skin. the back will have no center brace and Im worried about off balance deflections. |
01/16/2010, 10:44 PM | #5 |
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Don't be worried about it it will be fine with or without the skinned brace.
Kim
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Proud Member of the Idaho Marine Aquarium Society America will only be the Land of the Free as long as it is the Home of the Brave. Current Tank Info: AGA 180gallon tank, VHO/MH lighting, DSB, calcium reactor, Also a 7 Gallon Nano softy tank, and a 32 gallon cube |
01/16/2010, 10:47 PM | #6 |
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Use .75" 13ply plywood you will gain 1.5" on the inside of your cab. It will hold alot more than 700 lbs. As fore your idea a 2x6 will be better with no center brace. Using plywood will reduce any racking or sagging if constructed with the right placement and use of joints.
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01/18/2010, 09:40 PM | #7 |
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Thanks for all the input. Now, I am trying to get away with not using nailers. How do I attach the top horizontal bracing to the vertical struts without using nailers?
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01/18/2010, 11:23 PM | #8 | |
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center brace, stand |
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