Hi all,
I've started building a router table using plywood that I bought at Home Despot and Lowes. One sheet was a 3/4" maple ply from Lowes, and the other was a 3/4" birch ply from the despot. My design calls for about a dozen dadoes for different parts so I used my digital calipers to measure the thickness of the birch plywood (.724"). I then set up my dado in my table saw and made a test cut. This fit my sample piece of birch ply, and the maple ply perfectly, so I cut the remainder of the dadoes.
Well wouldn't you know. Apparently the birch ply sample I tested was the thinnest piece on the entire sheet because not a single piece of the cabinet parts fit into the dadoes. Not one, and not even close. I got my calipers out again and as it turns out, my test cut would not even fit the other end of my birch sample. It was off by .020". I measured some of the other pieces and the thickness varied by as much as .030" thicker than my sample. One piece even measured just over a real 3/4" at .755".
I have cut quite a few dadoes in plywood before, and I have had to tweak some of them, but nothing like this. So now I have a dozen dadoes that I need to tailor a few thou for each piece. I started by taking a piece of 1/2" mdf and gluing a piece of 120 sandpaper to it. That would work but it might be Xmas next year before I finsihed them all. I think I will go to Lowes and get some 60 or 80 grit to see if that would be faster. I did try one of those drywall sanding sheets. They are pretty aggressive, but they really don't last very long. I don't have any other hand tools that would be appropriate for the job.
I have a dado jig that I built for my old Porter-Cable 690 router, but I gave that router to my son. I would have to run some tests to see it it will still work properly with my Milwaukee 5616, Bosch 1617, or Bosch 1613.
Such is wood. Cut and learn.
X