80/20 aluminum stands
- Thread starter Usingthejohn
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aluminum is a superior material to use in tank stands because it's strength far exceeds what we would realistically need for an aquarium (unless you're talking 5-600+ gal tanks). it's light, rust resistant, etc.
the problem is that it'll cost you a lot more.
aluminum means you have to weld with a tig, which requires a much more expensive welder, and the welds themselves will be slower than a mig. not to mention the electrode itself is a wear item.
with aluminum, your welds have to be REALLY good. you really shouldn't be grinding away the bead.
bottom line, awesome material, plenty of strength, but it'll cost ya.
the problem is that it'll cost you a lot more.
aluminum means you have to weld with a tig, which requires a much more expensive welder, and the welds themselves will be slower than a mig. not to mention the electrode itself is a wear item.
with aluminum, your welds have to be REALLY good. you really shouldn't be grinding away the bead.
bottom line, awesome material, plenty of strength, but it'll cost ya.
re: "erector set" type stands. the aluminum is fine for the shell of the stand, that'll give you the vertical strength. the weak parts will be that the set will have little to no shear value. those corner bolt plates are not very good at resisting shear from a giant tank sitting on it.
to add shear resistance, you'll have to skin the stand with plywood.
also, the top will have to have 2 layers of 5/8" (min) plywood GLUED together, to distribute the weight to all the legs.
to add shear resistance, you'll have to skin the stand with plywood.
also, the top will have to have 2 layers of 5/8" (min) plywood GLUED together, to distribute the weight to all the legs.
I currently am waiting for an email back from 80/20 concerning load specs.
I did download their deflection calculator and this is what a single 66" long piece fixed at both ends does with 2500 lbs sitting on it...
Thats just over 1" of deflection, aslo keep in mind that is 1 piece
I did download their deflection calculator and this is what a single 66" long piece fixed at both ends does with 2500 lbs sitting on it...
Thats just over 1" of deflection, aslo keep in mind that is 1 piece
in math terms, it's perfectly fine for 250+. the strength of the material is very good.
however, the problem is the joints. these erector set have very weak (relatively speaking) joints, and have no built-in shear resistance, so when you put a 3-4000lb weight on top of it, and give it a sudden and hard shove (like in an earthquake, except it wouldn't have to be a big one), and the stand will fail at the joints, and the problem with aluminum is that it's very strong in the direction that it's strong, but not much else.
think of a beer can, when it's in perfect shape, if you tried to crush it against your forehead, you're going to have a massive headache and a big ring imprinted on your head. but if you put just a tiny dent in the side, the can will crumple around that and you'll be able to crush the can relatively easily.
same deal with these stands, except EACH of those corners with the bolts is like a dent on the side of a beer can, ready to crumple if the right force is applied.
however, the problem is the joints. these erector set have very weak (relatively speaking) joints, and have no built-in shear resistance, so when you put a 3-4000lb weight on top of it, and give it a sudden and hard shove (like in an earthquake, except it wouldn't have to be a big one), and the stand will fail at the joints, and the problem with aluminum is that it's very strong in the direction that it's strong, but not much else.
think of a beer can, when it's in perfect shape, if you tried to crush it against your forehead, you're going to have a massive headache and a big ring imprinted on your head. but if you put just a tiny dent in the side, the can will crumple around that and you'll be able to crush the can relatively easily.
same deal with these stands, except EACH of those corners with the bolts is like a dent on the side of a beer can, ready to crumple if the right force is applied.
The devil, as they say, is in the detail. What's the tolerance in those bolt holes? 1/32"? Seems pretty tight but consider that your shear is now dependent upon the tension strength of how tight the bolts are tightened.
If the tolerance is 1/32 (I'd be impressed if that's what it is) over the span of 3',the variation can create a lean of 1-3 degrees, turning your rectangle to a trapezoid.
Basically, how much do you trust how tight you can tighten those bolts.
Sent from my Note3 phablet
If the tolerance is 1/32 (I'd be impressed if that's what it is) over the span of 3',the variation can create a lean of 1-3 degrees, turning your rectangle to a trapezoid.
Basically, how much do you trust how tight you can tighten those bolts.
Sent from my Note3 phablet
