Stand built... suggestions?

[lokian]

Hi all,

Trying to layout my stand built and wanted to see what you guys think. Let me know if this will not hold the tank.

tank is a 220 gal... 72 x 24 x 30...

The upper rails is 2x8 and lower is 2x6... both have some 2x4 running across them to increase strength as well as allow a bigger space under the stand.

thanks guys.

[uncleof6]

3/4" plywood on edge will hold up this tank, so I would not worry a whole lot about your stand, holding up the tank.

Jim

[dzfish17]

From youre drawings I would say that structurally the stand would be very sound.

[meco65]

Going by the drawing the 2x6 and 2x4 legs need to be attached to the top and bottom 2x8s and 2x6s, The legs need to go from bottom of 2x6 to top of 2x8. If the top and bottom are just sitting on top of the stand it will not have side to side stability.
Notice the legs on the inside this will give the side to side stability.

[dots]

The 2x8's should do nicely for the span, just pick free heart center material, and when building it, put the "crown" up.

[lokian]

Going by the drawing the 2x6 and 2x4 legs need to be attached to the top and bottom 2x8s and 2x6s, The legs need to go from bottom of 2x6 to top of 2x8. If the top and bottom are just sitting on top of the stand it will not have side to side stability.
Notice the legs on the inside this will give the side to side stability.

So i should add another 4 2x6 in the corners that extend from the bottom up to the top of the stand on the insides? the green legs in your drawing right?

[meco65]

Ether that or mettle braces. You have to have side to side strength as well as up and down. IMO. Other than that you over all design looks great.

[reefermad619]

Ditch the green legs and use pocket screws. You'll get more usable space under that stand too.

[lokian]

it was my intent to go with pocket screws on this... so this design would then not need to additional green braces?

[reefermad619]

Nope. The green strips are not braces. They are more like nail strips. They're only there so one doesn't need to use pocket screws. The orginal design by rocket was a simple stand anyone could build with a saw and drill.

[meco65]

Pocket screws should work fine everyone just dose not have the pocket screw jigs and bits. Sorry not trying to give bad advise.

[lokian]

hehehe all good.. just wanted to make sure i was doing this right from the beginning... have some wood working skills but i'm no engineer :)

Going to end up putting 2 more cubes onto it... one on each side... lower then the main tank and then build some racks onto the wall.... to make one huge wall stand... wall is 12.5' by 9' and the tank will be at the center of it :)

[hebygb]

Either method is fine (green verticals or pocket screws .... or both). I would go with the green verticals because they allow the 2x8s to be screwed nearer the top as well. It is true that the green verticals will take up space, however, at this size, you should not have any issues with space.

I would advise agianst the metal reinforcment as it is not considered good practice.

[der_wille_zur_macht]

Pocket screws do not (or, should not) change the structural design of the wood involved in the stand! The green braces are not mere nailers, they also provide resistance to racking/twisting. If you're skinning the stand in plywood, you don't need that. But if you're not, I'd put them there regardless of the method used to screw the other boards together.

[meco65]

pocket screws do not (or, should not) change the structural design of the wood involved in the stand! The green braces are not mere nailers, they also provide resistance to racking/twisting. If you're skinning the stand in plywood, you don't need that. But if you're not, i'd put them there regardless of the method used to screw the other boards together.

+1

[meco65]

[/QUOTE]I would advise agianst the metal reinforcment as it is not considered good practice.[/QUOTE]



I was just saying that the metal is better than nothing.

[lokian]

k sounds like i will be adding in those 4 post just for security

[reefermad619]

Not needed. Are you going to skin it? I would add some gusset type supports instead of the long nail strips. All these stands are way way way overbuilt. My old 240 stand that I bought from my LFS was made of 3/4 ply and only had 1 piece of real dimensional lumber. It was in the back of the stand and it was a 2x6.

[Liquid Hobby]

Keep it as it is and wrap it in 3/4" plywood. That's how they shear houses! I built my 120 stand pretty much the same way, but it's wrapped on 3 sides with 1/2 ply, screwed on with deck screws to counter any shear/racking forces.

Might also consider a vertical support on the front...

[lokian]

its going to be skinned but i would like to use 1/4 to 1/2 ply....

i'm trying to avoid the vertical in the front to keep the space open for easier access to all the equipment.

Can i get away with something like that?

[Liquid Hobby]

I'd go with 1/2" ply. You can break/bend 1/4" with you hands - it's pretty flimsy stuff. The 1/2" will also give the screw heads something to hold onto without the fear of them just ripping out under a shear load. 2x8s span far greater than 72" in you house!

[lokian]

anyone got some info regarding not having a front vertical center brace.... but having one in the back?

[hebygb]

as mentioned above skinning will prevent the racking. I tend to over build my stands using the 4 (green 2x4s) because I like to have my oak panels removable. I use embeded neodium magnets to hold the panels in place.

Skinned stands are awesome... but as we all discover down the road... flexibility to "raise the hood" from time to time sure is easier to do when you can remove the panels. The added supports give me the peace of mind to do this.

[TheFishMan65]

lokian,
Rocket engineer originally posted
2x4 for a 4 foot span
2x6 for a 6 foot span
2x8 for an 8 foot span
This would allow for less than a 1/8 deflection. Not sure how he did the calculation, but those where his numbers.

[lokian]

lokian,
Rocket engineer originally posted
2x4 for a 4 foot span
2x6 for a 6 foot span
2x8 for an 8 foot span
This would allow for less than a 1/8 deflection. Not sure how he did the calculation, but those where his numbers.

yup hence the 2x8's on top and 2x6's on the bottom..

[ChadTheSpike]

The calculation is done using an equation for maximum deflection in a simply supported beam under a distributed load for the unsupported span of the tank.

It looks something like this:

d=(5*w*l^3)/(384*E*I)

where: w = weight
l = unsupported span
E = young's modulus for SPF
I = moment of inertia for the cross section

Just in case anyone was curious.

[TheFishMan65]

I have learned that for small glass tanks (< 4 feet) you only need to support the sides or 3 -4 inches from each corner. So I am curious how this affect the 1/8 deflection. Sounds like the plastic frame already handles that.

lokian,
Unless I am remembering wrong the tank was 6 feet so why the 2x8s? Or are you just being safe?

[ChadTheSpike]

^for glass tanks, it does, sort of...

Glass is extremely rigid, so it does not load the stand the same as an acrylic tank would in the long term. Generally, bending stress on the spans is the most limiting aspect, and between glass and acrylic, acrylic places more bending stress on the spans. So it is more conservative to base the stand design on an acrylic tank.

[lokian]

I have learned that for small glass tanks (< 4 feet) you only need to support the sides or 3 -4 inches from each corner. So I am curious how this affect the 1/8 deflection. Sounds like the plastic frame already handles that.

lokian,
Unless I am remembering wrong the tank was 6 feet so why the 2x8s? Or are you just being safe?

I was going off the original setups by i think rocketengineer...

was according to gallons and not the overall width... this tank is 6' but 24" wide and 30" tall. More of a load.

Plus safe is better then realizing the tank is going to fall over as it starts to lean with 240 gals in it :)