DIY 125g tank stand build.

Niki_up

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You didn't draw structural building plans for a living. ;)

It does make sense.

Each corner has two bearing posts. This third one is for different purposes.
Haha not unless highlighting completed demolition on building plans count haha

Thank you for the explanation
 

esoxlucius

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All diy custom stands are different. That's the beauty of making your own. You can measure it up to be inch perfect for the gap it's going in, or the height you want it so you can work down in the sump comfortably or reach inside your tank comfortably. Do you want an open front like on your example or do you want a centre support so doors can be affixed? You really are better taking a bit of time out and doing it yourself so it's exactly to YOUR liking, and not built from somebody else's plans.

The two circled ends of vertical 2x4's on that stand that aren't flush with the horizontal 2x6's aren't load bearing if you look at the construction of that stand. That's why the diy builder of that stand could leave them short, it was his preference, though personally I would have had them level with the top but it's each to their own. Again, that's the beauty of making your own.
 
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Ulu

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They just need to be ~ 1/4" short to allow for creep. Slight gaps. Settlement. Screw slip. Direct load paths. Broad stress distribution. Positive moment capacity. Esoteric stuff such as that.

I don't mean to baffle anyone with jargon here, but engineering is a notoriously non-intuitive business.
 

Ulu

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. . . . personally I would have had them level with the top but it's each to their own. Again, that's the beauty of making your own.
It looks like they should be level, by intuition, but that would be incorrect.

One single vertical #3 grade Douglas Fir 2x4, 24" long can carry the entire weight of 1500-2000 lbs.

In fact, if you can keep it dry by painting it so the wood doesn't rot it will bear a load of 4000 pounds.

Let me repeat myself.

One single 2 by 4 can carry twice the weight of your entire tank. You do not need the vertical load capacity of that short 2 by 4. You will already have 10 of them to carry the weight for a capacity of 40,000 lb.

That's a small swimming pool folks.
 

Ulu

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By the way that only discusses vertical load bearing capacity or what I call column loading.

The horizontal two-by-fours are called beams.

Vertical ones are called posts. (A "column" is usually built up out of several posts or is made of something really strong like Steel.)

The short two by four verticals are the lap splice blocks.

Anything you put in an angle would be called a brace.

Unless you put a plywood diaphragm on each side you may have the vertical capacity to support a Sherman tank but you will not have any capacity against racking sideways except bending of the screws in the wood.

That capacity is very low which is why you must have bearing posts and cannot just lap things and screw them together, without direct vertical bearing.
 

Ulu

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If you can figure out how to work this spreadsheet it tells you A two foot long 2 x 4 number 3 Doug Fir under dry conditions will bear 3989 lb. (I estimated 4000 up above based on my experience.)

That is for the cheapest grade of Douglas fir and if you use the best grade of Douglas fir it goes up to nearly double that amount.

A Select Structural grade Douglas fir 2x4, 2 ft long will support 7517 lbs. Nearly four u.s. tons!

 
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Ulu

Potamotrygon
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If you take a look at the stand pictured in the original photograph above, you see a stand with enormous vertical capacity.

It literally has 10 times the vertical capacity it needs.

But the horizontal capacity is not 10 times!

In fact, without installing plywood sides or diagonal braces, all horizontal capacity is determined by slippage of screws in the wood and bending of the screws.

By comparison, that is extremely weak, and while it may be sufficient in any particular case, it does not give you nearly the safety Factor you have on the lumber in bearing.

Lateral or sideways motion of the tank can cause the stand to fold over. How much capacity you allow can depend on many circumstances including whether you live in an earthquake zone.
 
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Ulu

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I know I am being pedantic here so please forgive me for the quintuple post, and kudos to any of you who have followed me this far.

One of the Prime reasons to make that short 2x4 short is so you don't have to measure and cut it exactly. While all the posts should be exactly the same length, unless you want to shim up a crooked stand, the "lap blocks" do not have to be any specific length as long as they are long enough and yet not too long.

The ends can be a little crooked or have a knot, and it doesn't matter because the ends aren't supposed to touch anything.

As soon as they do you can apply unexpected loads to screws and members which were not considered in your calculations.

Fortunately the DIY Joey type stand is cheap and so overbuilt for most of its needs, that it works pretty well even if you do a sloppy job.
 

Niki_up

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I know I am being pedantic here so please forgive me for the quintuple post, and kudos to any of you who have followed me this far.

One of the Prime reasons to make that short 2x4 short is so you don't have to measure and cut it exactly. While all the posts should be exactly the same length, unless you want to shim up a crooked stand, the "lap blocks" do not have to be any specific length as long as they are long enough and yet not too long.

The ends can be a little crooked or have a knot, and it doesn't matter because the ends aren't supposed to touch anything.

As soon as they do you can apply unexpected loads to screws and members which were not considered in your calculations.

Fortunately the DIY Joey type stand is cheap and so overbuilt for most of its needs, that it works pretty well even if you do a sloppy job.
Thank you for taking the time to respond to my thread throughly.

I’m am by no means a good diy, I would love to take the suggestion from above an design my own stand but alast I do not trust myself. So I wanted to use someone else’s design that has been tested and known to work.

I plan to installed side panels, a top, a bottom inside the stand and some kind of door or doors on the front with maybe a half shelf on one side for storage.

I do not plant to install a backing on it whatso ever, unless needed.

I also do not plan to use fancy pocket holes, just straight up screws into the wood, depressed into the wood with maybe a wood filler over the screw holes. I don’t necessarily need beautiful, just decent, and functional. The stand that came with the tank is not reliable for myself as it is on casters...not good for the weight on wood floors.
 
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