Is there a guide for designing aluminum extrusion stands?

[NeveSSL]

Hi everyone,

I'm looking for a guide on how to design extrusion stands. I've not been able to find one. I would like to design my own so I can have the features I want while being comfortable that it will hold the tank. The tank will be about 300 gallons or so.

Have I just missed it? Would anyone who has designed their own care to explain their methodology for doing so?

Thanks,

Brandon

 

[NeveSSL]

Found this thread and going through it now! https://www.reef2reef.com/threads/show-us-your-t-slot-aluminum-stands.302935/

 

[Reefer Reboot]

What did you have in mind?

 

[NeveSSL]

Trying to use aluminum without busting the bank. I am probably going to do a 96x30x24 peninsula tank. I want to be confident the stand will hold the tank, without over-engineering it and wasting money. Right now I'm thinking 2040 top rails and maybe 2040 corners with 2 middle 2020 center supports and 2020 for the bottom rails. Also using 45 degree gussets at each joint for additional rigidity. If that doesn't make sense, I'll draw it out.

Brandon

 

[dannyd_]

I have designed aluminum extruded stands not for a fish tank but for engineering machinery, a CNC router if you are curious. One thing that I found is that with the T Slots it is largely held together by the friction of the screws in the slots, rather then the tightness. So for your framework I would highly suggest making the top part of the frame a square that sits on post, rather then the top of the four post being level with the cross bars. This way the weight relying on the durability of the post, which is incredibly strong, rather then the durability of the mounts between the top frame and the post. If this doesn't make sense I can attach pictures.

 

[Reefer Reboot]

Here is the deflection calculator from the 80/20 website, https://8020.net/deflection-calculator .
+1 on what @riveradaniel just said.

 

[Tailfisher]

8020.com will assist you as they have a design dept that will calculate everything in there program and give you a parts list so you can order material and hardware to assemble. Good luck and post some pic's when done.

 

[Kjames]

^This.

You can use the deflection calculator on the 80/20 website to evaluate your design. Spend a few minutes getting familiar with the calculations and it will give you some clear answers about your design. Also could try their tech toolkit sotware.

Beam Deflection/Displacement Calculator | 80/20 Aluminum Extrusions

Use this calculator to determine the deflection or displacement of 80/20 T-Slots profiles with one fixed end, two fixed ends, or a load supported on both ends.

8020.net

 

[NeveSSL]

I have designed aluminum extruded stands not for a fish tank but for engineering machinery, a CNC router if you are curious. One thing that I found is that with the T Slots it is largely held together by the friction of the screws in the slots, rather then the tightness. So for your framework I would highly suggest making the top part of the frame a square that sits on post, rather then the top of the four post being level with the cross bars. This way the weight relying on the durability of the post, which is incredibly strong, rather then the durability of the mounts between the top frame and the post. If this doesn't make sense I can attach pictures.

I know exactly what you're saying, and that is absolutely what I was planning. I've seen several designs that have to top part screwed to the support instead of laying on top of it, and it drives me nuts. It may pass some of the theoretical design theories, but I hate it. lol I want that crap to just lay on top of the supports so you're not relying on ANY fasteners... just gravity while the fasteners keeps everything together.

I'm basically thinking of doing a 2040 top square with 4 cross members and 2 outside rails that sit on top of another 4 vertical supports that go down to a bottom square, also with 4 cross members and 2 outside rails, with gussets on everything to make sure it won't sway. I'm just trying to confirm this will be enough for my tank weight, which should be about 2500 lbs or so, I think. Also thinking I'm going to put 1/2" PVC on top and maybe 1/2" of closed cell foam, too. Trying to avoid wood if I can.

I'll check out that deflection calculator.

Thanks, guys!

Brandon

 

[Reefer Reboot]

Just to start you out, is this close to what you're thinking?

I used 40/40 in this sketch, not necessarily what it will be in the end, just trying to get the basics down first to make it easier to run the calculator.

 

[NeveSSL]

Wow, man! That's close! I was thinking two center supports instead of one. Also at least one cross brace on the bottom, maybe two.

 

[Reefer Reboot]

So more like this?

 

[NeveSSL]

Spot on!

 

[Reefer Reboot]

Cool, now all you have to do is run the calculator on all the lengths. I would have to mock up some 20/20 and 20/40 models to do it as per your plans. Personally, I would go with at least 40/40 which I'm sure would be strong enough in this configuration (IME), but then again, I've never run the calculations using 20/20 - 20/40, so it may be strong enough, IDK.

 

[NeveSSL]

Very cool. What kind of minimum deflection should I seek? And when I calculate, I should do 32" for the spans with the weight of the tank divided by 8, roughly?

Brandon

 

[Reefer Reboot]

Yeah, that should get you in the ballpark, roughly. Is the tank going to be glass or acrylic?

 

[NeveSSL]

Glass. Probably Planet Aquariums.

Brandon

 

[NeveSSL]

I actually think the weight needs to be divided by 6 as there will be 6 spans supporting it, basically.

 

[Reefer Reboot]

Then I would definitely try for the least amount of deflection possible. The two ends hold weight also. Plus whatever you use for a top shelf will help. The manufacturers can help you design it for structural strength, especially if you are buying from them.

 

[NeveSSL]

I believe I'm going to do my stand like Framing Tech's design, with a difference being having the bottom be the same as the top as far as having the bottom be one frame with the supports directly transferring the weight of the tank from the top frame to the bottom frame... I don't like the legs putting the weight on the floor. I'd rather that be spread out a bit. Probably doesn't make a huge difference, but it's easy enough to adjust for. At the same time, I'll probably have to shim it, which means not all of it will be flush, but oh well. I still like it better than all the weight just being on 8 legs.

Do I need to put a gusset on every corner? Most of the stands I see don't have any.

Brandon