I've seen these presses made from threaded rod with bolts and 1/2"
plates on the top and bottom with holes for the rod to feed thru. I
think this is a very dangerous short cut, as I described.
That depends on just what you build, and with what sizes of rods and
plates. If you go back to when Susan Kingsley was first exploring
hydraulic presses, before Lee Marshal came up with the Bonny Doon
press, She, and pretty much everyone else, were using home built
presses pretty much like this (though not 1/2 inch plate. That’s too
thin, as I recall). She’d had some engineer folks do the calculations
on what was needed, and designed a safe home built press. It was
published in an issue of Metalsmith, as well as in her book, I
think… That design, if built as specified, is sturdy enough to be
safe. I built one for under a hundred bucks when I found a garage
sale bottle jack and some scrap steel plates the right size. The
thickness of the steel plates, diameter of the threaded rod, number
and placement of the nuts, are all important, so don’t “wing” this.
And remember that with any press, home built, shop style, or Bonny
Doon style, even if the press is safe, workpieces placed in there may
not be. You don’t need the press to fail if what you put in it does.
Under a few tons pressure, bits of broken dies or tooling can attain
high speeds as they exit the press if you’ve not set it up safely.
If you’re working with hydraulic die forming, and you’re not sure
what you’re doing, especially beginners or those who’re self taught,
get a copy of Susan’s book. Well worth every penny.