DIY Stands Template and Calculator
- Thread starter JohnL
- Start date
bmanzie
New member
Anything?
Menace2Sobriety
New member
I'm not a rocket nor am I an engineer but if I were building a stand for a 600 gal tank I wouldn't use a single 2x4. I'd go overboard just in case and use all 2 x 6 or 2 x 8.
Rhodophyta
New member
For my 520 gallon, I put a 2 by 12, a 3/4" plywood sheet cut to fit the face of the 2 by 12 less the top 3.5 inches, and a 2 by 8 against the plywood.
All glued and clamped together. Then the short way across I put 2 by 4's on 1.5 inch centers. They rested on the ledge made by the plywood and the 2 by 8.Then for the ends and back wall I used the system used to make a stud wall in a house, except on 12" centers, and glued 3/4" plywood with a cedar face onto the new "walls" which went from floor to ceiling.
Rhodophyta
New member
The GARF design Rocket's and so many others resemble often use 2 by 4's on the bottom, or a bottom shelf and four corner legs with center legs in longer stands. Some place them on edge and others set them flat, as they would be in a residential wall. One advantage of placing them flat is more contact surface area with the floor, and if you wish to be fancy, decorative work can be done on the exposed edges with whatever kind of tools at your disposal.
http://www.garf.org/calculators/BuildLargeStand_3.asp
What is on the top of the stand's structure and between should be your concern, not just the bottom. My stand held a 520 gallon tank and a 250 gallon tank. It used 2 by 4's laid flat as the contact with the floor, which was a rebar reinforced ten inch concrete slab.
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The 2x4s are simply there to spread the load out a bit and provide some support against the legs from bending outward. It's also a handy place to put a shelf, which would certainly brace the frame up a bit more. There's no reason at all to use 2x6 for the bottom frame, it's my opinion that a bigger bottom frame would actually decrease stability, since it would shift the transition higher up and move the center of gravity higher. At least until the bottom frame is wider than the length of the legs...
Somewhere in this thread (or the first part) there's a post that suggests a single 18" length of 2x4 can support up to something like 19,000 pounds or so on end before it would blowout. That doesn't account for bowing, warping, or any lateral (side to side) force, which would obviously cause premature failure, but still... if you figure there's 8 2x4's supporting these stands, that gives you 152,000 pounds of support - over 75 tons.
A safety factor of 5 (overkill) means you get over 30,000 pounds of support.
At 8.556 lb/gal sea water, 500 gallons would be 4,278 pounds - with rock and sand, you could get to (maybe) 5200 pounds. Provided you have adequate top frame support for the tanks weight 2x4's are more than enough to support that load for the legs and the bottom frame.
The bigger concern that the capacity of the 2x4 to support a downward force would be lateral forces... if someone leans on the tank, or if it's not 100% level, aggressive wavemaking, seismic activity... the taller the stand the more this is an issue. So while the 2x4 will suffice on their own under ideal circumstances, it would probably still be a good idea to sheath the entire stand in some 1/2 plywood, or add some kind of diagonal bracing. Over building the legs with 2x6 would add some lateral bracing, but nothing close to what a plywood skin would offer. (queue "plywood is all you need!" crowd)
Somewhere in this thread (or the first part) there's a post that suggests a single 18" length of 2x4 can support up to something like 19,000 pounds or so on end before it would blowout. That doesn't account for bowing, warping, or any lateral (side to side) force, which would obviously cause premature failure, but still... if you figure there's 8 2x4's supporting these stands, that gives you 152,000 pounds of support - over 75 tons.
A safety factor of 5 (overkill) means you get over 30,000 pounds of support.
At 8.556 lb/gal sea water, 500 gallons would be 4,278 pounds - with rock and sand, you could get to (maybe) 5200 pounds. Provided you have adequate top frame support for the tanks weight 2x4's are more than enough to support that load for the legs and the bottom frame.
The bigger concern that the capacity of the 2x4 to support a downward force would be lateral forces... if someone leans on the tank, or if it's not 100% level, aggressive wavemaking, seismic activity... the taller the stand the more this is an issue. So while the 2x4 will suffice on their own under ideal circumstances, it would probably still be a good idea to sheath the entire stand in some 1/2 plywood, or add some kind of diagonal bracing. Over building the legs with 2x6 would add some lateral bracing, but nothing close to what a plywood skin would offer. (queue "plywood is all you need!" crowd)
RocketEngineer
Space is big.
I recommend against the unsupported overhang. What purpose does that serve? I see it as introducing stresses into the tank that can be avoided.
Floyd R Turbo
Either busy or sleeping
RE you would probably have something to say about this stand then
http://www.reefcentral.com/forums/showthread.php?t=2365838
Thread is not updated on RC, the tank is installed and I commented with quite a level of concern on his thread on another site, if you google "1000 Gallon 3D Hole wall" you'll find it. I about downloaded in my pants when I saw the cantilever he had in there (bigger than the original CAD design he shows, like 12"). Make sure to read his responses to my posts. Interested in your take on my evaluation.
http://www.reefcentral.com/forums/showthread.php?t=2365838
Thread is not updated on RC, the tank is installed and I commented with quite a level of concern on his thread on another site, if you google "1000 Gallon 3D Hole wall" you'll find it. I about downloaded in my pants when I saw the cantilever he had in there (bigger than the original CAD design he shows, like 12"). Make sure to read his responses to my posts. Interested in your take on my evaluation.
bmanzie
New member
The overhang will allow me to stand and work on the inside of the tank.
What about the rest of the design?
SPotter
Active member
Unless you have really small feet, I dont think a 6" ledge is going to do much for you. I think you would be better not having that ledge and build something completely separate from the stand that will accomplish what you are trying to do.
How important are the bottom rails and ends? We have wood floors and I wanted to look at following RocketEngineer layout but keeping it so I could get under the stand to wipe up water, etc. I envision using pocket screws and having the outer 8 2x4s act as legs to the ground. I would put rails and ends in between the legs a couple inches off the ground. Would I have to worry about the legs giving out at the bottom?
Rhodophyta
New member
Sorry the pic is aimed at the tank, but this stand has the bottom horizontals up above the ground about 8 inches. It had been set up as a 300 gallon reef tank, but is in limbo right now.
The stand is welded steel, powder coated. Paneling attaches with magnets so it can be pulled away for complete access. I have wooden stands with feet about a foot below a bottom shelf which holds a second tank, up to 125 gallons. How you attach the bottom horizontals makes all the difference.
Do you mean the extra legs?
If you use the right beam size for the top frame you don't really NEED the extra legs, so any you add should be enough.
