Here's my update from today:
Schwarz didn't have any transverse supports attached to the aprons, he screwed his directly to the top, I thought I would add to the torsion box design and give some more support by rebating in some 2x4 supports, these will then have some 3x1 glued to their face to provide a support area to put in some screws (with oval screw clearance holes to account for wood movement) which will hold the top flat - it will be glued to the first 6 inches of the apron and supports.
I also finished up shaping the corners of the aprons, and finally glued on the front apron of drilling the dog holes.
Pics:
Supports added to the leg rail:
Front Apron glued on:
Notched transverse supports placed into position - and their rebates marked on the aprons
Nearly broke my back getting the bench up onto the sawhorses
I sawed by hand the shoulders,routed out the excess and finally, I squared them up with a chisel
Test fit is good
Glued and clamped up - along with the front apron, these will be left over night, tomorrow I face the daunting task of jointing and flattening the tops.
I've spent approx 28 hours so far