Another t-slot stand design (and question)

[cartery]

Hello!

I am trying to build a stand out of 3030 t-slots as is often discussed on here. However, both my display tank and sump are standard 40 gallon breeders, so the usual designs I see won't work.

I have come up with the design attached below. My plan is to have the sump basically resting on the floor, which is concrete, so I'm not really worried about support there. The area created by the beams labeled "D" in the 3D renderings will create a little cabinet space, so again, no real worry about load. However, for the display tank, I'm not sure how to figure out if this design is sufficient.

Assuming the total "profile load" is 500lbs, I can use the 80/20 deflection calculator (https://8020.net/deflection-calculator) to get a deflection estimate of .08 of an inch for the cross beams labeled A that run front to back and are supported on both ends. But this is what's confusing: The profile load should actually be some fraction of the total tank weight, right? Would it be 1/7th, since there are a total of 7 beams supporting the bottom of the display? If so, then I obviously need to calculate deflection for the beams labeled D, as well.

Any thoughts would be very welcome! Thank you!

 

[threebuoys]

I'm not familiar with the product you intend to use; however, most aquariums of this size have a frame around the bottom so that all of the weight is on the perimeter. The beam across the middle will provide rigidity to the structure but will not actually touch the tank nor share the load.

 

[cartery]

I'm not familiar with the product you intend to use; however, most aquariums of this size have a frame around the bottom so that all of the weight is on the perimeter. The beam across the middle will provide rigidity to the structure but will not actually touch the tank nor share the load.

Hmm. My intention was for the cross member to share load. I actually just had an engineer friend come over to chat about this and I think I'm gonna go in a different direction. Thanks for replying, though!

 

[William Chiavetta]

Hello!

I am trying to build a stand out of 3030 t-slots as is often discussed on here. However, both my display tank and sump are standard 40 gallon breeders, so the usual designs I see won't work.

I have come up with the design attached below. My plan is to have the sump basically resting on the floor, which is concrete, so I'm not really worried about support there. The area created by the beams labeled "D" in the 3D renderings will create a little cabinet space, so again, no real worry about load. However, for the display tank, I'm not sure how to figure out if this design is sufficient.

Assuming the total "profile load" is 500lbs, I can use the 80/20 deflection calculator (https://8020.net/deflection-calculator) to get a deflection estimate of .08 of an inch for the cross beams labeled A that run front to back and are supported on both ends. But this is what's confusing: The profile load should actually be some fraction of the total tank weight, right? Would it be 1/7th, since there are a total of 7 beams supporting the bottom of the display? If so, then I obviously need to calculate deflection for the beams labeled D, as well.

Any thoughts would be very welcome! Thank you!

What software are you using to design this?

 

[BeanAnimal]

Hello!

I am trying to build a stand out of 3030 t-slots as is often discussed on here. However, both my display tank and sump are standard 40 gallon breeders, so the usual designs I see won't work.

I have come up with the design attached below. My plan is to have the sump basically resting on the floor, which is concrete, so I'm not really worried about support there. The area created by the beams labeled "D" in the 3D renderings will create a little cabinet space, so again, no real worry about load. However, for the display tank, I'm not sure how to figure out if this design is sufficient.

Assuming the total "profile load" is 500lbs, I can use the 80/20 deflection calculator (https://8020.net/deflection-calculator) to get a deflection estimate of .08 of an inch for the cross beams labeled A that run front to back and are supported on both ends. But this is what's confusing: The profile load should actually be some fraction of the total tank weight, right? Would it be 1/7th, since there are a total of 7 beams supporting the bottom of the display? If so, then I obviously need to calculate deflection for the beams labeled D, as well.

Any thoughts would be very welcome! Thank you!

It depends on the tank. Most (but not all) glass tanks are perimeter supported and most acrylic tanks are designed to be somewhat fully bottom supported.

So the first questions would be: What type of tank?

 

[cartery]

It depends on the tank. Most (but not all) glass tanks are perimeter supported and most acrylic tanks are designed to be somewhat fully bottom supported.

So the first questions would be: What type of tank?

It's a standard glass 40g breeder. It's got the big black braces on top and bottom.

 

[cartery]

What software are you using to design this?

This is PowerPoint and the free idea builder on 80/20. I'm then also using the deflection calculator on 80/20.

 

[BeanAnimal]

It's a standard glass 40g breeder. It's got the big black braces on top and bottom.

As mentioned above (threebuoys), the perimeter of the tank will carry the full load. The cross bracing on the stand is there for rigidity and does not carry load.

 

[cartery]

I sat down with an engineer friend and we redesigned the stand. The new design looks like this. The big change is that I'm planning to use 4040s for the main spans and 2040s places vertically elsewhere.

 

[BeanAnimal]

If you are not skinning 3 sides of the stand with a rigid skin, you will want corner gussets to prevent twisting or racking.

 

[cartery]

If you are not skinning 3 sides of the stand with a rigid skin, you will want corner gussets to prevent twisting or racking.

Yes, definitely, thank you! I actually just learned what racking is lol.

The plan right now is gussets, but I might add some rigid siding, too. I was thinking I'd get the pieces to build this version, put the empty tanks on there to plan plumbing, etc., and then decide on panels.

 

[BeanAnimal]

Sounds like a plan. Let us know if you have more questions.

 

[cartery]

Sounds like a plan. Let us know if you have more questions.

Will do! Thanks for engaging the with this!

 

[Marcus H.]

Why is the tank top not sitting on top of the vertical post? They way you have it attached any weight distributed on the tank top will be felt on your braces/brackets. I would have it so the corner of your rimmed tank is directly above the corner vertical post. I hope this makes sense. I literally just designed and ordered 3030 to make a 40 gallon breeder stand

Edit: The image below is from Tenecor. Look at how the top of their stand sits on the vertical posts.

 

[BeanAnimal]

Good catch. I did not even bother to look at that.

However, given the loading, I am sure that properly secured hardware will be fine with the current configuration. 4 posts, 8 connections.

500 pound tank is 125 pounds per leg. 60% on front 40% on side (give or take) So ~75 pounds of shear on the most stressed joints. Add safety factor (you leaning on tank) and call it 125 pounds per joint. Well within the bounds of the 80/20 hardware for shear, pullout, slipping or other deformation.

Add gusset brackets and the stresses are even less of an issue.

 

[Marcus H.]

The other thing I see is that the long span is 935 or 36.8 inches. So only the corners will be supported. The width (sides) of the tank will not have a support underneath it. I don't know enough about how rimmed tanks distribute the weight so that would bother me.

 

[cartery]

Why is the tank top not sitting on top of the vertical post? They way you have it attached any weight distributed on the tank top will be felt on your braces/brackets. I would have it so the corner of your rimmed tank is directly above the corner vertical post. I hope this makes sense. I literally just designed and ordered 3030 to make a 40 gallon breeder stand

Edit: The image below is from Tenecor. Look at how the top of their stand sits on the vertical posts.

I don't have the corners directly above the legs because I want a sump with the same footprint (another 40g breeder or a 28g lowboy). Since the display will be directly over the sump, I can't think of a way to have the corners of the display over the legs.

Where did you order from? Have you got the stand yet?

 

[Marcus H.]

I bought the T slots from 8020 and the fasteners from Zyltech. If you look at the T slots on each website they are basically the same. A few measurements are off .01 mm. The fasteners on 8020 are $$ but for your stand I would buy the best fastener I could find.

I got cute and bought the profiles that have flat sides. My wife is sure I screwed it up. I'll let you know when everything shows up. This is a first time for me so I'm sure I will learn some lessons.

I see what you mean on your sump.

 

[BeanAnimal]

The other thing I see is that the long span is 935 or 36.8 inches. So only the corners will be supported. The width (sides) of the tank will not have a support underneath it. I don't know enough about how rimmed tanks distribute the weight so that would bother me.

I think for a 40 gallon it will be fine. While I don't agree and never bothered to do the math, there are plenty of folks who support 90's 120 longs, etc just by the ends on concrete masonry units...

I would prefer to see the ends of the 40 supported. If not, the deflection for the front and back rails needs to calculated at ~250 pounds each plus a safety factor (leaning on the tank say).

 

[BeanAnimal]

Marcus - consider putting cross members under the ends. They can be narrower profiles. This does not remove load from the front and back, but does transfer it there through the extrusions instead of solely relying on the tank panels to do it by leaving the end unsupported.