OK. The table.
The table from the CNC machine is going to be made up of a torsion box, I think 5″ high (4″ risers, 3/4″ top, 1/4″ bottom). There will be some legs supporting it, but the torsion box is the part I have to really plan for, because the support structure will be made out of dimensional lumber, which is relatively easy to deal with, where the torsion box will be made out of sheet stock, which can be tricky.
The top will be 52″ x 120″ (but maybe 124″). The bottom will be 48″x116″ (maybe 120″). The grid will consist of twelve 15″ long pieces, and four really long (96″ plus 24″) ones. The whole thing is going to take 4 full sheets of MDF. I’ve decided to do MDF, because plywood is a lot more expensive, especially for those unseen interior bits. That build will be tough enough to complete; by the end of it, I’ll be really good at the table saw.
But, before I can even start on the torsion box, I need to build a structure for the table saw itself to support those big pieces of sheet stock while I’m cutting them.
I found a set of plans on the web for a pair of “wings”, 2′ wide by 8′ long tables that attach on either side of the saw. I will probably need an “outfeed” table also, a structure that sits behind the saw. It would need to be about 4′ wide by .. well, I’m not sure how long it needs to be. In fact, I’m not really sure how big the whole thing needs to be. I need to think about my cut plan, and see how much structure I need:
1) in front of the sawblade
2) on the sides of the sawblade
3) behind the sawblade
And think about how the layout needs to change when I’m cutting something 8′ wide and 4′ deep versus cutting something 4′ wide and 8′ deep.
For the cuts that are “wide”, I believe that all of the cuts are too wide to be accommodated by the rip fence on the saw. So I will need both a “left hand” wing (to support the sheet stock), and a “right hand” wing (which will have a “fence” built into it, probably a board clamped to the structure at the correct distance and of course dead parallel to the blade). For “wide” cuts, however, the stock will only protrude off the back of the table by about 3′, with the two cut pieces being almost 4′ square. The table saw itself is 40″ wide, so about 20″ on each side (it’s actually more on one side and less on the other, I think) will be unsupported behind the blade, assuming no outfeed table. That does leave 24″-28″ (that is, “more”) of the board supported on the “wings”, so it might balance out ok (as in, boards will want to stay on the wings rather than fall in to the center, which could be disastrous). I need to understand that better. And it’s probably best to have an outfeed table anyway.
For the cuts that are “long”, I’ll be able to use the existing fence (the cuts will be 3″ wide but 8′ long). There will be about 7 of these (the rest, I can cut the sheet shorter instead, and just use the wings and fence to do the work, I think). Catching 7′ of sheet stock, whether it’s the 3″ wide piece or the 4′ wide piece, is tricky. I can probably use one of the wings in double duty for that; I would only need a “left hand” wing (because I’m using the regular fence), so the “right hand” wing could be pressed into service as a 2′ wide by 8′ long outfeed table (I assume I’d attach it to the spillover portion of the left-hand wing). The left-hand wing is already providing 2′ wide by 3′ long support for the board on the outfeed end. That’s not really enough, I guess — there would be 2′ wide by 5′ long unsupported.
I’ve just had a thought; I can just use a roller for the supports (infeed and outfeed) on the long cuts. I’ll still need the wings, but the rollers might help me get everything balanced out.