What about a fabricated English Wheel frame:
You could have a multifunctional frame laser cut from plate and welded up.
Would love an English wheel but that design of frame wouldn’t work with what I need to use mine for.
It’ll largely for riveting sheet ovens together so the jaws need to reach right to the back of a deep box
If I did do a lever type one the bottom jaw would not need to have such a long unsupported length as without a cylinder mounted on the upper jaw they’d be nothing to foul the ovens slidinging into the throat.
The downside would be that the machine would be deeper and so take up more room in the shop. Something I don’t have much of!
Rivet the bottoms on first and poke the anvil through where the side plates will go .
A picture or a sketch would help .. there is a lot of expertise and engineering problem solving mind power on site just yearning to help you .
Does it matter which side of the tank the rivet bulge is ...… on the inside or on the outside ?
How many rivets per hour would you hope to set .
There is a guy selling 6mm plate in Taunton, it would be perfect for a fabricated pair of arms.Very true, wouldn’t buy me a huge amount more clearance though