Bob La Londe writes:

https://www.youtube.com/watch?time_c...&v=f2xlAWytx9g

I know some folks may not be a fan, but I noticed he made his main
uprights out of 1/4" steel plate welded up into a box.

I just made a deal on a small quantity of 4x8x1/4 A36 plate for about
half local metal yard retail. I'm going to use one piece as the top
for my welding table until I run across a good deal on something
thicker. I decided to buy some extra just because the price was good
enough to be worth sitting on it for a while.

I've been want a little better hydraulic press for a while. I have
pulled my 12 ton partially apart. I can still use it, but only above
the torn metal. LOL. My 20 ton now has a bow on the top beam.
That's what happens when you try to press a prop hub out in the wrong
direction.

Anyway, I was wondering if 1/4 plate really was adequate for the
uprights on something like that. I have no need to make one as tall
as stretch built his in the video. I won't have a joint in the pieces
like he does, and I wasn't planning on going 50 ton. I've got a
pretty beefy 30 ton cylinder and power unit off of a log splitter I
was thinking about using for the hydraulic part. My 20 ton has been
adequate for anything I needed to press except for the fact that I
managed to bend it. I've also got some heavier stock for things like
the top and table.

Ok, tell me how stupid the idea of using 1/4 plate and making my own
upright tube is.

The frame "uprights" of a press (hydraulic press) are in pure tension.
Very rare engineering loading case. Abnormally easy to treat.
Opposite of instability - the load "assists" pulling them straight.
Load bearing in this very special case is totally simply to calculate
on-paper:
multiply the cross-sectional-area (width*thickness)
by the
yield stress divided a safety-factor (say 5?)
and there you have it.

Typical other cases:
In a beam you have to consider buckling instability, etc.
Likewise a column (it looks the same as a "tie" but is in
compression).
The engineering design is much more complex and you have to work out
which effect comes to the fore in most limiting the load-bearing
capacity.

Hope this is helpful comment...
Regards,
Rich S