Which of these will strongest connect three panels?

Question

I'd like to assemble essentially a cube made of aluminum panel walls (30 cm x 30 cm x 4 mm sheets), with an emphasis on stability/strength of the cube.

Since I don't have welding knowledge, I'd prefer to use (internal) connector brackets to connect each corner of every three panels; i.e., a total of 8 corners.

Based on research of easily/inexpensively available parts, I've come up with the following three options. (The idea being I'd use multiple of these, taking care of all inner-corner combinations of my panels.)

Question: How would these rank; will one of these be significantly stronger than the others in connecting the three aluminum panels?

Answer 1

B seems like the obvious choice.

You can easily rule out A because it will require two brackets, minimum, and even with those two, one of the seams will be weak. To make that seam strong, would require a third bracket, and it is generally undesirable to increase part count when you can achieve similar results with a smaller part count. (But I'll admit you didn't say that was part of your criteria).

C has the same problem. Two of the panels will be tightly connected to one of the panels, but one of the seams is weak and can flex open more than the other two.

The obvious advantage to B is that each panel will be directly tied to the other two panels, which means every seam will be much tougher to separate (flex open) than A and C.

Another thought: B in the corners with A at the midpoint of the panels would be a really nice tight box.

Answer 2

I've work in the machinery industry for 38+ yrs. Depending on the thickness of the material I would say probably item C. Either self drilling sheet metal screws or if cosmetics is not an issue bolt with a nylok lock nut. Good luck.

Answer 3

a is no good because it only anchors two panels, b is no good as the fasteners are too close to the outer corners (to weak of a connection) so c would be my choice.

but how are you going to mount these brackets. you wont be able to get at the interior ones on 4 corners once 5 of the faces are attached. are you using blind rivets?

Answer 4

Some of the other answers here seem to miss the fact that you would use three of the A brackets in each corner to tie the three panels together.

I am going to make the assumption that you are going to use nutplates & bolts to assemble the box, with through holes in the aluminum plates. I am also going to assume that the bolt head will be on the outside of the box and the nutplate affixed to the bracket on the inside, because how will you tighten the bolt head from the inside for the 6th side?

Taking all this into account, I think A is your best option for strength. However, it will take more care in mounting the brackets than the other two options to ensure the corners line up properly. You'll want to space them as closely together as possible without interference. In fact, I'd probably discourage this method unless you are trying to use your box to lift a car.

I think a modified version of B is your best overall option for simplicity and ease of installation - I would go with something like this:

This will allow you to put the nut on the inside (or possibly better yet, tap the holes to match your bolt thread and screw your bolt directly to the bracket itself, eliminating the need for nutplates).

In either case, you could add additional A brackets along the sides of the box for extra strength.