My original design was of a single screw press and while I have found some early pictures of them the two screw presses and screw and lever presses seem to be more suitable for the period which I'm interested in, 14th-16th century.

The problem I'm having with the design is not the rupture of members or excessive bending it is the shear at the joints which is dictating huge timbers.

It may be that I'm just trying for too much pressure. Something I have learnt from experience is that the press does NOT get the juice out of the apple. The mill gets the juice out of the apple. The press gets the juice out of the pomace (pulp). Given that I'm thinking that the pressures I'm after may be excessive. Also if I'm developing my pressure from one or two wooden screws (instead of cheating with a hydraulic jack) then it is likely that the screws will bind before the press members break if I size them based on what looks right from my eye and the pictures.

Still comes back to shear though. Bending and rupture I feel I have my head around. Shear is still hazy.