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Old 07/24/2007, 06:59 PM   #1
RocketEngineer
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DIY Stands Template and Calculator

The reason for starting this thread is to provide a template for a relatively simple DIY stand design. This design is a compilation of several designs into one place and includes the calculations needed to generate a cut list for any custom design.



The basic principle of the design is two box frames connected by four legs. The upper one supports the tank and transfers the load to the legs. The legs are made of several pieces of 2X4 to assist in construction and sheething the stand in plywood for strength and cosmetics. The bottom frame transmits the load of the tank into the floor.


Design notes:
*The plan for this stand consists of 21 pieces. Like color pieces are the same length and of the same board size.
*The box frames are screwed together first, then the legs are built off the bottom frame, the top frame is then placed on top and secured to the legs.
*The green pieces are screw strips. These provide limited load strength but serve to make assembly easier and help keep the stand square.
*The blue piece between the upper rails (red) works to keep the upper rails from twisting.

Ok, now to the cut list:
First off: The calculations below are based off of a stand that is "W" inches wide X "D" inches front-to-back X "H" inches high.

(2) Red - Upper Rails: Length = W
These will be sized according to length: 2X4 for 48" or less for smaller tanks (Rule of thumb is 75g-90g); 2X6 up to 72" with 125g-150g being acceptable; For longer spans and larger tanks 2X8s are recommended.

(2) Yellow - Upper Ends: Length = D-3"
Theses will be made of the same material as the upper rails.

(4) Green - Screw Strips: Length = H-2"
These 2X4s are shorter then the tank is tall.

(8) Purple - Uprights: Length varies:
- 2X4 Upper Rails: Length = H -7"
- 2X6 Upper Rails: Length = H-9"
- 2X8 Upper Rails: Length = H-10.75"
These 2X4s support the weight of the tank. The ones on the short sides of the stand provide a flat surface for attaching a plywood facing and while they do provide some strength, they are optional.

(2) Orange - Bottom Rails: Length = W
These 2X4s act to spread the weight of the tank over a larger area.

(3) Blue - Bottom Ends: Length = D-3"

Covering the sides of the stand with plywood will help to stiffen the stand against twisting and shifting. Doors can be mounted to the legs as desired.

So there it is. 21 pieces in 6 lenghts equals a tank stand that should fit the bill for most people. There are other plans out there but this is a simple design using simple tools and common wood sizes. It may not suit everyone's application but it should fit the bill for most common size tanks.

Should someone wish to have me calculate beam strengths for a specific application, PM me with the tank dimensions and I will be happy to run the numbers.

Happy building.


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Last edited by geo; 12/08/2011 at 06:15 AM.
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Old 07/24/2007, 07:33 PM   #2
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Nice writeup. I'm sure this will come in handy to people building their first stands. It's very similar to how I built mine.

One thing to add...

If you plan to put plywood on top of the bottom frame then two more blue pieces should be put in at the 1/3 and 2/3 locations on the bottom orange rails. This would be beneficial to keep the plywood from warping over time if a sump was put down there.

Otherwise you could place the bottom frame on top of the plywood.


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Old 07/27/2007, 09:20 PM   #3
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Bump


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Old 07/27/2007, 09:49 PM   #4
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Would I need to use 2x6 entirely for a 72" 150 or just for the top box? Also, at 72" with this design, are you saying there is no need for a additional upright supports, just the 4 corners?

Dave


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Old 07/28/2007, 06:28 AM   #5
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Your first statement was correct. For this design, you only need the top frame out of 2X6 for an unsupported 72" frame. If you have all eight purple uprights, no additional vertical support is required.


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Old 07/28/2007, 07:13 AM   #6
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Alright, thanks. I may be making a trip to the lumber yard today.

Dave


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Old 07/28/2007, 08:16 AM   #7
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ok---why wouldnt the 2 top yellow pieces be the same width as the 2 top red rails
why arent the 2 bottom blue sides the same color, brown, as the 2 bottom rails
i would make the 4 sides on the top all red, and the 4 bottoms all brown , and i would add 1 piece, possibly 2 pieces from long top to long bottom, to support the back red rail, and possibly 1 piece in the front so doors could be used


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Old 07/28/2007, 09:36 AM   #8
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Re: DIY Stands Template and Calculator

Quote:
Originally posted by RocketEngineer

(2) Yellow - Upper Ends: Length = D-3"
Theses will be made of the same material as the upper rails.
I don't know why the bottom sides are blue, but I understand it. As far as the middle supports, I suppose you can add whatever you need to complete the stand, however, I believe the OP is stating this is the basic frame design that will support the aquarium.

Dave


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Old 07/28/2007, 09:48 AM   #9
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ok---right----a basic design, sorry bout that
but, as far as a basic design, instead of using 2 pieces for each corner, i would think using 4x4 posts would give the stand more stability and screw the 4 top pieces and the 4 bottom pieces to the posts
just thought by adding the using post comments someone , if they build it using the 2 pieces per corner wont end up having their tank end up on the floor
good start tho
steve


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Old 07/28/2007, 11:56 AM   #10
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Hurtback, first of thanks for the comments. Constructive criticism is always welcome and helps work out the kinks.

As to why use the three pieces per corner (two purple and one aqua), the purple pieces under the red members are required, where as those on the ends under the yellow and red are optional. The aqua piece acts as a screw strip and works to keep the stand square especially if screwed from both sides of the corner.

Why I chose to use two 2X4s instead of one 4X4 was a matter of tools and load paths. Most people have some way of cutting off a piece of wood but not everyone has the tools to notch a 4X4 or drill pocket screws to angle them down into the top. Also, for this same general reasoning, the two piece leg means that the load goes straight from the top frame, through the leg, into the bottom frame and the floor. The weight of the tank is not held up by the screws.

Thanks everyone for the comments and keep them coming.


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Old 07/28/2007, 01:29 PM   #11
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hi RocketEngineer, i did nt mean what i said as Constructive criticism , just a thought to possibly add along with what you have said/done already. i just thought to use the 4x4's to support the load. I myself would use the 4x4 posts, with 1 or 2 more along the back and possibly 1 along the front. your right, maybe someone out there doesnt own the right tools to notch out a 4x4 post, or to even cut a 4x4 post for that matter.i would even double brace both top and bottom to make sure that once i put the tank on top of my stand, thats where i want it to stay.
the more people add to your design, the better off someone might be down the road once they build their stand
steve


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Old 07/28/2007, 03:12 PM   #12
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That design works prettry well for most tank stand with 2x4s no need to use 4x4. If just one 4x4 in your support legs twists, turns or wraps you're !@#$% big time. Having said that, 2x4 also warps but the margin is very small by using multiple 2x4s in one support leg. Another plus point of using 2x4 is that you don't need bunch of tool to work with in the first place as stated.

The template seems very useful when it comes to making DIY stand. And if one doesn't have power saw, those pieces can be easily cut to size at HD no sweat.

I wouldn't make any stand using 4x4. The thought of it warping in one leg gives me chill in the spine.

In the end, one still has to decide what materials to use which best suit in his/her application.


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Old 07/28/2007, 04:00 PM   #13
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Sigh, I wish I could find the info, but 10 minutes of googling has produced nothing.

Anyone know the compression/load strength of a vertical 2x4? 2x6? 4x4? What about on a horizontal member? How much deflection is too much? I'd just like to see some numbers to make a point to people how strong some materials actually are when used properly. And how easily overkill is created.

Great thread, RocketEngineer. Ok, now how about a Ti stand template and calculator?


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Old 07/28/2007, 04:19 PM   #14
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how bout a *sticky*


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Old 07/28/2007, 04:43 PM   #15
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Ok, Siffy. Being a student, here is the original source of information I used and continue to use when looking at lumber in a stand setting.

Full Document portal:
http://www.fpl.fs.fed.us/documnts/fp.../fplgtr113.htm

Specifically, Chapter 4: Mechanical Properties of Wood
http://www.fpl.fs.fed.us/documnts/fp...tr113/ch04.pdf

For those with the background, the number I typically employ within my beam bending calculator is 4000 psi. A piece of Douglas Fir has a rupture strenght of ~7000 psi when GREEN! This "Strength of Rupture" is determined experimentally and considered the working value for lumber under bending loads.

As to what deflection is acceptable, personally I work for 1/8th inch and this is typically more restrictive then the strength of the beam.

Should anyone have any questions, let me know. I will be happy to post the equations I use for those interested.


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Old 07/28/2007, 04:57 PM   #16
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*sticky* would come in very handy.


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Old 07/28/2007, 05:15 PM   #17
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I wasn't trying to argue your material/size usages at all. Quite the opposite. Thanks for the document, but I don't really understand many of the variables involved.

So I'll just ask... Does that 7000psi equate to saying a fir 2x4 can support a weight of 7000 lbs * 1 3/8 * 3 3/8 = 32484.375lbs? I've got to be missing something... Got any numbers in force rather than pressure? On say a single 32" long vertical 2x4. I'd bet just 1 could come close to supporting the weight of a 240g tank, and most people just don't realize that.

Just a note, I'm a CPE and we never dealt with wood in any questions in my Statics class. And another side note, I hate working with wood. I was joking about Titanium, but I would much rather build a stand structurally out of steel, and then just skin and trim with wood.


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Old 07/28/2007, 05:23 PM   #18
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hi ya---4x4 posts will not warp if the top rails and bottom rails are screwed to each end of the post
what might warp would be the longer pieces of the top and bottom rails, without any type of support
4x4 's need to be out in the hot sun in order for them to dry out, but remember, they will be inside, probably a sump will be running, and the moisture created by the sump will keep the 4x4 posts from drying out
i would much rather have 4x4 posts holding up my tank instead of 2x4 or 2x6's
again---my opinion, thats how i will build mine, and of course, everyone can build there own how the see fit, but its a good start RocketEngineer
thanks
steve


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Old 07/28/2007, 06:09 PM   #19
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are you saying you would prefer to drill directly into the 4x4 , or are you talking about notching out the corners and resting the 2x4's on the notched out section(then screwing in place). Only because you wouldn't want the screws to be your weakest link , and only support really


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Old 07/28/2007, 07:18 PM   #20
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leebo_28, you are correct, the screws taking the load would be a dangerous situation. For a 4X4 posts without notching, I can't think of a good way to attach the frames to the legs.

Again folks, this design is meant to be made by folks with minimal tools. Also, the strength of wood in compression is incredible. Look at any tree and consider how much it weights. A single 2X4 under compression in one of these stands could take something like 18000 pounds unless it buckles sideways. For those wishing to use 4X4s and have the tools, I don't see a problem. But a couple 2X4s in each corner are more then enough for most tanks.

Cheers.


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Old 07/29/2007, 01:54 AM   #21
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Heck a 2x2 in each corner would easily support the vertical load... they just would not have much lateral stability


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Old 07/29/2007, 06:17 AM   #22
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Quote:
Originally posted by BeanAnimal
Heck a 2x2 in each corner would easily support the vertical load... they just would not have much lateral stability
They wouldn't have to if the back and sides were skinned with even 1/4" plywood. The only problem with 2x2s is mounting the top rails in a position that screws aren't load bearing. A couple 3/8" SS carriage bolts per corner should suffice, but that would completely change the original design.


Hmm, RocketEngineer, how do the deflection properties of a spanning member relate to thickness? IE, 2x4 vs 1x4 or 1x6 etc? I think I read a factor of 3, but I'm not certain. The goal is produce a competently stable yet lightweight stand right?

The last stand I saw a friend build was 5 layers thick when looking at it from the bottom. It was so heavy I made sure I was out of town when time came to carry it upstairs where his new 4' 120g was going.


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Old 07/29/2007, 12:24 PM   #23
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If you had two boards of the same height and length but one half the thickness of the other, the beam with half the thickness would be half the strength. If you increase the height, (a 2X4 vs a 2X6) you increase the strength as a function of the height cubed (3.5^3= 42.875 vs 5.5^3=166.375). So increasing the board height is the best way to make the long spans stronger and reduce deflection.


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Old 07/31/2007, 02:44 PM   #24
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Ok folks, I ran a couple numbers last night. One 2X4 on end, 24 inches long, will support 19000+ pounds before it deflects sideways enough to fail.

Oh and BUMP.


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Old 08/04/2007, 10:52 PM   #25
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Hi, what would be an optimal stand height for a 12" high tank?


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