Plasma cut sign from steel - How thick?

[Craig F]

I am plasma cutting a 4’ x 8’ outdoor sign with a pretty good bit of the metal removed for the logo and lettering. The sign will be two sided with an internal perimeter framework of 3” channel and internal led lighting. 1/8” thick acrylic will be on the inside of the steel sheet. Other than the perimeter frame, there won’t be any other framing. I am wondering if 1/8” thick mild steel will be enough for the 4’ x 8’ sign or if I need to jump it up to 3/16”? I am wanting to make it as light as possible.

Thanks

[adbuch]

My feeling is that 1/8" (11 ga.) should be sufficient for your application. But of course 3/16" would be fine too, and a little bit more stiff.
David

[DieselFumes]

I think 1/8 should be fine since you have a sturdy frame and acrylic backer, bonding the steel to the acrylic is also an option if the steel gets a little wavy in spots. I would consider aluminum also if it suits the finish you have planned for it as it would be much lighter for such a large sign and is easier to manipulate if you get some warpage.