Press strenght calculations

[Idris]

I am thinking of building a lightweight press similar to Mongo and G-man.

I having difficulty finding any information on strength calculations for steel tubes. I thought I'd remembered someone posting a link or a rough how to on the forum but can't find it anywhere.

I'd rather not just guess, build and test as I've ended up doing with some fabrication projects in the past - always ended up over building in my ignorance due to safety fears. Once I built a small boat (for a 15ft thing that a few guys could lift) trailer that ended up being plenty strong enough to carry a jeep!

Thanks