Greetings. This is my first post here. My woodworking experience is mostly in building things for utility, but I do like it when fit and finish turn out right.
I have a small area of the garage in which I can have a moderate-sized work surface. I'd like it to be flat so that pieces can be assembled to fit right. I have visited a few online articles and videos about building a torsion box (just google it), and I believe that I understand the principles that make it work. It relies on a top and bottom "skin" with a uniformly thick and flat spacer material composed of wood pieces glued in a tight grid. it forms a 3-dimensional I-beam. I have thought of a way to build a torsion box (or imitation of it) that may be easier to build and almost as good. I certainly would value the advice of the community on this approach while it is still in the design phase. I have some drawings of the concept, but I am not sure what is going on with pictures in this forum, so I'll try to use words instead.
Here is my idea:
1) create a temporary but flat work surface. I may be able to borrow some metal square tubing for this. I would need some adjustable feet (or various shims) to get a flat surface. My thought is to use a laser level and possibly check with a good 6-foot level to verify flatness. Flatness is required, level is a good idea but not required.
2) Use two new interior slab doors to create a uniformly thick and flat spacer material. Lay one door on the square tubing and check for flatness. Attach anchors and/or weights to the sides of the door as needed to make it flat. Dry fit a second slab door on top, discover placement of weights and anchors to make the combination of doors flat. Then glue the two doors together.
3) Add the "skins". Use a similar gluing method to add a 3/4 ply (maybe one side melamine?) to the stack, then turn the whole thing over and add a 3/4 ply to the other side.
4) Build a bench. Build up horizontal beams to support bench top from ripped and glued 3/4 ply on edge for dimensional stability. Add legs with adjustable feet to make it level.
Could this work?
One person I spoke with said that I was assuming too much with regard to the flatness and consistency of the interior doors. I picked interior doors because the inside is supposed to be some material on edge and well-sealed with glue and not likely to change with humidity.
I have read about something similar, but made by gluing only pieces of plywood together. It is tough, but very heavy. The resistance to bending lies mostly in the outer layers; hence I thought interior doors might work better for the core.
Thanks for any advice or pointers towards information.
Tom