I’m trying to read up on all the different table versions/approaches. I’m keeping in mind the basic approach recommended by Ryan: KISS (keep it simple stupid). Still - I’d love to have a box/sandwich/table that we can keep the LR4 on, that we can rest on a few simpler tables or folding work stands etc. And if we have to move between workshops, it’ll be (somehow) transportable.
So - my question thus is: could it be beneficial to new (and old) builders to have a suggested plan/drawing for a full sheet table, using full sheet size? The drawing could then be used for cuts on an exisiting CNC or projected on a plate and then cut using other kinds of saws. I’d like to help out making this! But I don’t know from an engineering perspective what is the best balance between simplicity/portability/stability/etc
Ryan has pointed out, and it’s a very good point, that a torsion box table is only as flat as it was made when it was built, and building one flat can be challenging. If using cross-lap joints like I did in my build that I videoed and shared, it can help to get flatness during the glue-up, but while a shorter height for the ribs and spars helps with lowering weight, it also introduces possibility of flex during construction. Conversely tall height for ribs and spars helps with getting flatness, but adds to overall weight of the table. This could be countered somewhat by staying thin on the top and bottom skin, which I did not do, but wish I had. Even if flex in a rib or spar is not glued in, twist can occur (overall). It hurts to have to say this, but having a large flat table helps with making a large flat table, and most of us who need to build a large flat table, need it because we don’t have one. In my case I had a large, not real flat table from my first try, and yet it served as my build surface for my second table. Sorry if this is not real helpful. Just trying to share some points to consider.
A valid approach would be to build the torsion box, and then surface the top with the machine before putting the top skin on.
This doesn’t need to be a full surface as it need only be the ribs and spars of the torsion structure, requiring only that the machine ride on parallel rails.
If you are going to surface the spoilboard, all that is really required is that the box does not move. Torsion boxes are pretty good at this.