Tslot stand

[rygh]

A simplistic calculation will show it stronger with vertical supports all the way to the top.

Your "end support points" for the horizontal member moves inwards. It is resting on those angle brackets,
not the verticals. So you effectively reduce the span by several inches.
Reducing the span reduces the deflection.

However, as above, I do not trust those screws in the channel.
All that force (1000 pounds / 4) is held up purely by the friction of the nut and bracket against the channel.

 

[aqua-nut]

That would be lots easier to build and not use as much materials.

How much do the sides need to be supported? I know with a framed glass tank you only need to support the corners. I've seen many commercial racks that only support the tank from the short ends.

 

[Flagg37]

All that force (1000 pounds / 4) is held up purely by the friction of the nut and bracket against the channel.

I agree.

 

[Vhuang168]

A simplistic calculation will show it stronger with vertical supports all the way to the top.

Your "end support points" for the horizontal member moves inwards. It is resting on those angle brackets,
not the verticals. So you effectively reduce the span by several inches.
Reducing the span reduces the deflection.

However, as above, I do not trust those screws in the channel.
All that force (1000 pounds / 4) is held up purely by the friction of the nut and bracket against the channel.

Actually, not all the force is being held up by the friction force only. The load is also resting on the 4 verticals. The screws are not there to hold up the horizontal but is used to clamp the horizontal to the vertical. The force is not an even downward force but rather a rotational force trying to pull the top of the horizontal away from the vertical.

If you used the correct connector, specifically an anchor, you have to drill a hole through the body of the extrusion to install it. While a part of the anchor does ride in the channel of the other Tslot, it is very secure.

Much of the force is similar to wood stands that use horizontals screwed into the side of verticals. The load is split between the vertical and the deflection of the horizontal trying to rip out the screws if it is allowed to bend.

If the force were split solely on the horizontal pieces only, then the only thing holding up the tank would be the shear strength of the screws!


Sent from my iPhone using Tapatalk

 

[rygh]

Actually, not all the force is being held up by the friction force only. The load is also resting on the 4 verticals. The screws are not there to hold up the horizontal but is used to clamp the horizontal to the vertical. The force is not an even downward force but rather a rotational force trying to pull the top of the horizontal away from the vertical.

Mostly disagree.
First, the load is distributed (unless your stand has major deflection) in which case, only
a tiny part of the load is sitting on those verticals.
Second, the rotational force would would be true if only one end was unsupported,
or if there is so much deflection that it appears unsupported.
But for a beam supported on both ends, the little bracket becomes part of that beam,
so really almost all downward force.
So agree/disagree depends on deflection.

If you used the correct connector, specifically an anchor, you have to drill a hole through the body of the extrusion to install it. While a part of the anchor does ride in the channel of the other Tslot, it is very secure.

Ok. That will help a lot.

---

Note that putting the horizontal beam on top of vertical has its downsides as well.
Those tubes do not have the thickest walls, and there is a large crushing force
on the horizontal one right at the joint.

 

[Vhuang168]

Mostly disagree.
First, the load is distributed (unless your stand has major deflection) in which case, only
a tiny part of the load is sitting on those verticals.
Second, the rotational force would would be true if only one end was unsupported,
or if there is so much deflection that it appears unsupported.
But for a beam supported on both ends, the little bracket becomes part of that beam,
so really almost all downward force.
So agree/disagree depends on deflection.

I think in a perfect situation where the horizontal beam has no deflection and the load is sitting solely on the horizontal, then you may be right. The friction of the anchor riding in the channel will be the only force holding the load. But the load in our situation also rests on the verticals which means the only movement downwards will be limited by the allowed deflection on the load.

Also, in real world application, any horizontal will have deflection. Even under no load and only with its own weight, it will sag. 80/20 lists the deflection at 0.006", while not a lot, it is still a deflection. So this means that any load placed on it will not be totally evenly supported but will have a distribution centered around the deflection. Any amount of deflection will result in a transition from a solely downward force to a more rotational one (maybe rotation is the wrong word) or a force that pulls on the anchor along the axis of the beam rather than on an axis perpendicular to the beam. I think that is why the calculated deflection is less using attached beam rather than a supported beam.

After thinking about it, I'm quite comfortable using the extrusion as they are designed, meaning using anchors and attaching them to the verticals. But I will use a double height extrusion (1.5" wide but 3" tall), double anchors and will have 45deg supports between the horizontal beams and the vertical supports at the necessary locations.