Hi Dave,
Thanks (once again) for your compliments. I'll take into consideration your advice about the dog's legs vs. the table legs. I don't think Festool makes the right tool for lengthening Wally's legs
Arching the underside of the slab was an interesting exercise. First I marked the arch on the side of the slab. I marked the mid-point of the slab, and the points where the legs ended (toward the middle of the slab), and then marked 3/4 inch up from the bottom of the slab at the midpoint. I then used a thin piece of wood (a spline) to join those points in a smooth curve. I had my wife hold it while I marked the curve on the side of the slab with a pencil. I was careful to make the gradient of the curve the same where the slab met the curve of the legs underneath the table.
Once the arch was marked, I set the depth of my ATF55 to the depth of the arch at the center of the slab (the deepest cut). Actually, it was about 1/16 th of an inch shallower, to leave room for error/sanding later. I then cut across the slab, leaving a kerf the right depth, and the width of the blade. Next I moved both left and right, decreasing the plunge depth, cutting kerfs about every 3/16 of an inch (very approximately), working my way toward the ends of the slab. This was quite an effort - I cut about 100 kerfs. Both my saw and my arm were tired at the end. I didn't use the guide rail for this (and I can see now why the guide rail is such a good thing - not all my cuts were straight, but it didn't matter...).
With all the kerfs cut, I had to remove the waste material. First I was going to use my chisel. But I found it faster to just hammer sideways on the inter-kerf pieces (probably a technical name for that, but I don't know it), knocking them out. You want to be careful to hammer against the grain so that you don't create a big divot if a piece falls out, taking adjacent material with it (DAMHIKT :-\).
The bottom was quite a mess after I got all the bits out. But the RO125 was up to the task: I started with P36 (I think), and worked my way up to P100, getting a nice fair curve over the whole underside of the slab. I then attached the legs and shaped them, and faired those curves into the table top. Some fine-tuning with the Rotex, and it was ready for final sanding. As I said in the post above, I think the underside of the table is more beautiful than the top. Not that you get to see it much!
At this point, if I were doing it again, I'd do it just the same way. It's fairly brute force, but quick, and it works. It's probably hard on the saw, making so many short cuts, but I think Festools are up to the task. You definitely want to have a good sander to smooth things out after chipping the wood out between the saw kerfs.
Even with the table arched, and a large amount of material removed, it's surprisingly heavy. Just from a weight point of view, I'm glad I thinned the top. I also think it gives it a graceful aspect.
Hope this helps!
Poto
