I’m making my table to the specs mentioned in the documents. It’s over the size of a 4 x 8 sheet and I’m going to try my hand at building the torsion box, I think it looked like people used three-quarter MDF…somebody had a calculator somewhere that created plans and I’m still trying to figure out if there’s anything I’m supposed to tweak on that calculator.
That being said, I guess I’m a little confused how I can make the cuts for the torsion box if I don’t have the table fully built. I’m going to be adding four supports that are perpendicular on the top of this build and I’m positive that I am overthinking this, but can someone help me figure out how I make my first cuts if the table is not completely finished yet 
Table build
You can make a basic table from a 4x8 sheet of plywood or mdf with your X axis travelling across the 8’ direction however wide that is, giving you about 3’ on your Y axis.
That’s what I’ve done here: New Build in Southern Oregon - #14 by dhiltonp
Then you can do tiling cuts, cutting sheet goods in sections. I’ll have to do that to cut my strut plates. The basic idea is you add a couple of holes every 3’ (because that’s how much Y travel you have).
On the first cut you also cut 4 holes in a square in the corners of your piece, to move the board you align 2 holes in the top with the other 2 holes in your spoil board with pins, on subsequent cuts you only cut 2 holes where the pins aren’t.
My problem is that I have metal conduit for the 9ft table.
My initial setup prior to making the torsion box would be 3/4 MDF, 1/4 hardboard as the spoil board? Followed by the 3/4 MDF I’m cutting for the torsion box & rails.
I’m confused about how to mount the rails for this process 
What should or can I put under it to make it cut initially ?
A shorter piece of conduit is cheap.
But if you don’t want to go that route, get two 4"x10’ pieces of molding (or similar) and install your conduit on that, and screw it to your 2x4s to keep it in place.
I just want to mention that a piece of MDF screwed onto your 2x4 rails is likely to be pulled and warped by the 2x4.
You’ll want to make sure that the horizontal edges of the rail are straight with a known straight edge like a level, or a string pulled taught.
But but don’t worry about the top of your EMT or other rider board being straight for now, small variations in Z height don’t matter much when cutting sheet goods.
