> I can't guess how you will be raising/lowering the tower

The tower will go against my workshop, a 24'x32' building, not the shed in the picture. I'll reinforce the workshop wall, like I did in the shed, and use a pulley to redirect a winch cable off to the far side.

> I can bend a 36" long piece of 1/2" rod

I can't say that these formulas are the right ones to use or that my interpretations are correct:

What I found for mild steel gives a yield strength of 40,000 psi. That'd be a strength of 40000 psi times a cross sectional area (.25" x .25" x pi) for your 1/2" rod = 7854 pounds. Grabbing it on the ends give you a 144 :: 1 mechanical advantage so it takes 7854 / 144 = 54 pounds to deform the rod. Does that sound about right? (give or take a bit?)

An inch long bolt of the same material would have the same strength (or less because of the threads) but you can't bend it in your hands; you don't have the same mechanical advantage.

> Why didn't you get a 1" pipe [?]

I looked at pipe... It all came down to thinking that whatever I fabricated, eventually it would be held to the concrete base with a 1/2" or 5/8" anchor bolt... a half inch of steel was going to be the weak link in the chain. Given that, it didn't appear to me that the other parts mattered so I did away with them.

But maybe my thinking is the weak link of the chain!