Having trouble with size

Hello
First post. I own two CNC machines that cut plastic and wood panels. I've tried to figure-out how to calculate the depth and width of cold rolled steel for a project but I'm not getting it.

I have a cantilever with a 16 inch square base (footprint) and the bar connects to the middle of the perimitter approximately 28 inches up.

The connection is welded with no deflection. My question is what the dimensions of the bar should be to support 300lbs, with no flex, approximately 12 inches from the connection on the perimeter.

Ideally the bar should be .375 thick.

Any input would releive my strain on my brain.
Thank you very much.

A picture is worth a thousand words.

(And what do two CNC machines cutting plastic and wood have to do with it?)

What do two CNC machines have to do with it?

I was hoping that someone might realize I'm a serious builder and not assume I am not serious. Please excuse my lack of math knowledge. I am very sorry that I bothered you. You obviously have never asked for help before.

You misunderstood my response. It was not a slam on your math knowledge. It was a serious suggestion that a diagram or picture of the situation would help us all understand your question better. I've read your post several times and I cannot get a picture in my mind of what you are talking about. Maybe its just me, but I doubt it. And my question about the CNC was also serious. It wasn't clear to me how the structure you were describing relates to the CNC machines.

Magic, don't get huffy, I thought JB's response was right on the money. We are here to help, but, we can only help when we understand the problem.

I refrained from posting on this as I was with JB. I cannot fathom exactly what it is you require and I was also awaiting a picture or more details. It is a common problem here with people posting about something that is crystal clear in their mind, but is difficult to understand for the rest of us.

Probably 70% of my first replies to a posting from a new poster is "more information or pics," and that gets pretty tedious after a few years here. So get over the petulance and let's get this sorted out for you. You do not need to demonstrate seriousness, we are happy to help anyone with real problems to solve.