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Guppy rack build


Zoro
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Hi guys, im in process of building small rack for some guppys, and would like to build it from extruded aluminum. This would be my first rack build and first time building something with T sloted extruded aluminum. So if someone has any experience with it i would like some input. 
Plan is to you 30x30 mm extrusion but not sure if that would be strong enough ?

Guppy Rack.PNG

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So the corners of the tanks don't have any vertical boards underneath them? Seems like it's relying just on the horizontal boards and whatever is being used to attach them. But I'm not a structural engineer or anything of the sort, so I don't know if that's an issue or not.

 

EDIT: Smarter posts start below. ⬇️

Edited by StephenP2003
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30mm extrusion is more than enough. From some napkin math, you've got at least a factor of safety of 5 for the extrusion. The only thing I would change in the design is put the columns on the outside of the horizontal pieces, and make the horizontal pieces 1 long extrusion. It will make putting plywood down a lot easier, as you wont need to cut slots for the columns.

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12 minutes ago, Phirefase said:

30mm extrusion is more than enough. From some napkin math, you've got at least a factor of safety of 5 for the extrusion. The only thing I would change in the design is put the columns on the outside of the horizontal pieces, and make the horizontal pieces 1 long extrusion. It will make putting plywood down a lot easier, as you wont need to cut slots for the columns.

If I got it right then tanks would be recesed inside for a extrusion thickness.

And how did you calculated that safety factor if I may ask, so I know for future and maybe even go with size down extrusion 

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1 minute ago, Zoro said:

If I got it right then tanks would be recesed inside for a extrusion thickness.

And how did you calculated that safety factor if I may ask, so I know for future and maybe even go with size down extrusion 

MECHANICALC.COM

This page discusses the calculation of stresses and deflections in beams.
EXM-3030.jpg
WWW.TNUTZ.COM

These extrusions are 100% compatible with the following manufacturers: T-SLOTS #670007 Bosch-Rexroth #3 842 502 538 McMaster #5537T97

I don't have the willpower to explain how beam stress works in a forum post. If you want to learn, the first link explains it, and the second link gives the properties of extrusion. Doing the napkin math for 20mm extrusion, you end up with the horizontal beams failing. I am assuming all the weight is a distributed load side beam(666N/m), which is wrong on many levels, but gives a worst case scenario. I end up getting a maximum tensile stress of 400MPa while the tensile strength of aluminum is 200MPa. I must stress this is all THEORETICAL WORST CASE SCENARIO so take it with a grain of salt. In the real world you might be fine with 20mm but I would just stick with 30mm.

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1 minute ago, MickS77 said:

I'd suggest plywood sheathing (not osb) instead of particle mdf board. 

The extruded aluminum sounds like a great idea. 

I wrote particle board because I'm not really sure what is called in English. Basically that sheet material is used on truck trailers for flooring, its hard and sturdy and water resistant

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1 minute ago, Phirefase said:
MECHANICALC.COM

This page discusses the calculation of stresses and deflections in beams.
EXM-3030.jpg
WWW.TNUTZ.COM

These extrusions are 100% compatible with the following manufacturers: T-SLOTS #670007 Bosch-Rexroth #3 842 502 538 McMaster #5537T97

I don't have the willpower to explain how beam stress works in a forum post. If you want to learn, the first link explains it, and the second link gives the properties of extrusion. Doing the napkin math for 20mm extrusion, you end up with the horizontal beams failing. I am assuming all the weight is a distributed load side beam(666N/m), which is wrong on many levels, but gives a worst case scenario. I end up getting a maximum tensile stress of 400MPa while the tensile strength of aluminum is 200MPa. I must stress this is all THEORETICAL WORST CASE SCENARIO so take it with a grain of salt. In the real world you might be fine with 20mm but I would just stick with 30mm.

Thanks for help, yea il use 30 mm, price difference isn't so big so better safe then sorry. Since you are familiar with extrusions from what I see which connector types would you suggest for this ?

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COMBO-030-B.jpg
WWW.TNUTZ.COM

30 Series M6 x 1.0 Standard T-Nut & 12mm long Button Head Cap Screw, TNUTZ Part #COMBO-030-B.
CB-030-A.jpg
WWW.TNUTZ.COM

Click here for suggested hardware 100% Equivalent to the following manufacturers: 80/20 - P/N 14073 T-Slots - P/N 671213 Bosch Rexroth -...

I like using these type of connectors. The only hitch is that the t-nuts have to be loaded in the end, so if you forget to put them in you have to use these. The big t-nuts just feel more stable, but I don't know if there's any benefit.

QT-015-1-4-20.jpg
WWW.TNUTZ.COM

They are 100% compatible with the following manufacturers: 1/4-20 - 80/20 #13110 10-32 - 80/20 #13112 8-32 - Unique M6 - 80/20 #13117 M5 -...

You don't have to get these specific ones, just find some at a hardware store or on amazon. Just stick the brackets on every corner and you should be fine. For the plywood, I don't see a need to fasten it down, the weight from the tanks should be enough. Maybe add some rubber grip stuff on the bottom if you want.

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5 hours ago, Andy's Fish Den said:

Check out Tidal Gardens on YouTube he is using this material for the stands in his new facility that he has been building out. He has some large tanks on it, along with casters so that the tanks can be moved if need be.

 

Actually saw that video while doing research and i like caster idea but i wouldnt put so high rack on it like one im building and those 4 casters are pricel like my whole rack 

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1 hour ago, Zoro said:

Actually saw that video while doing research and i like caster idea but i wouldnt put so high rack on it like one im building and those 4 casters are pricel like my whole rack 

True, I wouldnt use on a multi-level rack either, I was going to see how much that stuff was, but never did. I don't think he has spared any expense with his buidling.

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