Alohhhhhhhaaaaaa!

I am working on a design for a single-swing aluminum gate, approximately 4" high by 13" ft long. The gate would be a plasma-cut sheet/plate of aluminum, framed out in aluminum rectangle tube; either 1.5"x3"x.125" or 2"x3"x.25". For design aesthetics, I want to avoid adding a vertical support tube right in the middle of the gate, and am trying to figure out what thickness I should use for the plasma-cut panel so that it adds structural support. The panel itself has a lot of negative space (white areas in picture) so its not all that heavy (150-250 pounds).

The panel includes a sheet/plate border of ~3" inches on all sides, and will have to be done in two sections (no way I can source aluminum plate that big in the middle of nowhere Hawaii...)

Any and all thoughts appreciated.

Honestly, if you weld it all the way around, you could go pretty thin. The stress would be carried evenly across it. The big issue would be how easily it would dent. I would go over 1/8” thickness. Don’t over do it, the lighter it is the better. It will be similar to air craft construction, where the thin skin carries a significant portion of the load.

Keep it fun,

David

Check with your local highway department sign shop and find out what aluminum the road signs are made from and who/where to get it. I don't recall the designation but it's armor type al and is more rigid and way tougher than basic al. 

I think you'll need to put a diagonal in  a gate that size and proportions to keep it from twisting but you can camouflage it by cutting the same pattern into sq. tubing at an angle it blends. 

Frosty The Lucky.

IMO a 13' gate is pretty long and will have a tendency to sag a bit unless it has a VERY stiff frame.  I would stiffen it with an 1/8 or 3/16" cable diagonally on the back side of the gate from the upper side of the hinge end to the lower corner of the free end.  It will be almost invisible behind the patterned Al sheet.

BTW, very attractive pattern. will it be laser/water/plasma cut?

Long way from Rhode Island to a Hawaiian Island.  (My late wife grew up in Honolulu.)

"By hammer and hand all arts do stand."

Thanks all for the input! Lots to chew on!

You may also want to consider which alloy/grade of aluminum you select for this gate.