I posted a reply to another thread with an awsome tank and stand. I have realized after looking at many of the DIY projects that we have a shortage of engineers here. Or at least they are not speaking up. Many stands are being built without proper bracing. The main force that your stand must withstand is the force of gravity. Gravity, of course, pulls the weight of your tank straight down. It also causes a side to side force if your stand is not perfectly plumb.
Here is a crash course in Trigonometry and Statics: imagine an icecream cone standing on its pointed end with one edge straight up and down. Ok, now scrap the cone image and replace it with a similar triangle (2-d) with the top horizontal edge square to the vertical edge. The angle that the triangle is standing on will be the only angle refered to in this discussion. The vertical edge represents the total force directed downward. The horizontal edge represents the amount of lateral force (the longer it is, the more lateral force). The edge at an angle connecting the other two represents the actual direction of the resulting force (the other two forces add together to give this resultant - This math is vector calculus and is well beyond any lay discussions). When your tank stand is perfectly plumb, this angle is zero and all of the force from the weight of the water is entirely directed along the vertical members in the stand. There is zero lateral force. If this angle is increased to 90 degrees, all of the force of the weight is directed to the side - imagine holding your tank out to your side on the end of a long board. (This example is flawed and is only offered to help the layman. The actual force at 90 degrees is the entire force pushing to the side.) If your tank stand experiences the entire force at 90 degrees, it is because it has faild and the parts are on the floor. Anyway, these are the two extremes of lateral force: zero force at zero degrees, and 100% of the force at 90 degrees. At zero degrees, the horizontal member of the triangle is non-existent and at 90 degrees the vertical member is non-existent. As the angle increases from zero to 90 degrees, the lateral force also increases.
Now imagine that you have your tank on a table with four legs. The legs are parallel but not plumb. The weight of the tank is evenly divided among the four legs. Let one leg represent the triangle edge at the angle in the above example. The greater the angle, the stronger the force to cause the legs to fold under the table and send the tank falling to the floor. This force that causes the failure of the table is the lateral force. The heavier the tank, the stronger this force is; just as a larger angle is a similar variable. The following equation can be used to calculate the lateral force for your tank stand. It also shows that larger tanks need more bracing than smaller tanks.
[(volume in gallons) x (8.333 pounds per gallon)] x sin(displacement measured in degrees)
(You will need a scientific calculator because of the sine function.)
In the following post to another thread, I used an individuals large tank stand as an example.
Here is a crash course in Trigonometry and Statics: imagine an icecream cone standing on its pointed end with one edge straight up and down. Ok, now scrap the cone image and replace it with a similar triangle (2-d) with the top horizontal edge square to the vertical edge. The angle that the triangle is standing on will be the only angle refered to in this discussion. The vertical edge represents the total force directed downward. The horizontal edge represents the amount of lateral force (the longer it is, the more lateral force). The edge at an angle connecting the other two represents the actual direction of the resulting force (the other two forces add together to give this resultant - This math is vector calculus and is well beyond any lay discussions). When your tank stand is perfectly plumb, this angle is zero and all of the force from the weight of the water is entirely directed along the vertical members in the stand. There is zero lateral force. If this angle is increased to 90 degrees, all of the force of the weight is directed to the side - imagine holding your tank out to your side on the end of a long board. (This example is flawed and is only offered to help the layman. The actual force at 90 degrees is the entire force pushing to the side.) If your tank stand experiences the entire force at 90 degrees, it is because it has faild and the parts are on the floor. Anyway, these are the two extremes of lateral force: zero force at zero degrees, and 100% of the force at 90 degrees. At zero degrees, the horizontal member of the triangle is non-existent and at 90 degrees the vertical member is non-existent. As the angle increases from zero to 90 degrees, the lateral force also increases.
Now imagine that you have your tank on a table with four legs. The legs are parallel but not plumb. The weight of the tank is evenly divided among the four legs. Let one leg represent the triangle edge at the angle in the above example. The greater the angle, the stronger the force to cause the legs to fold under the table and send the tank falling to the floor. This force that causes the failure of the table is the lateral force. The heavier the tank, the stronger this force is; just as a larger angle is a similar variable. The following equation can be used to calculate the lateral force for your tank stand. It also shows that larger tanks need more bracing than smaller tanks.
[(volume in gallons) x (8.333 pounds per gallon)] x sin(displacement measured in degrees)
(You will need a scientific calculator because of the sine function.)
In the following post to another thread, I used an individuals large tank stand as an example.
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1/2" cabinet quality plywood outside a 4x4 and 2x4 support frame.
