I’m working on a large Shaker Cupboard in the shop. The sides for this piece are too big to hoist up onto my table saw for a two-step rabbet for the backboards. When that occurs, I turn to my router and a 3/4″ router bit with a top-mount bearing (or pattern bit) – I keep that router bit setup in my router all the time. (Yes, you need more than a single router in your shop.)
Generally, when working with this router setup, I also use a shop-made straightedge. I position the straightedge on my work exactly where I need to run the rabbet, groove or dado and make the cut allowing the bearing to ride against the straightedge. This time, due to the length of the case side and the resulting rabbet, I had no straightedge long enough to make the cut; of course, I could have pulled another router out of the cupboard, loaded a rabbeting bit set for a 3/4″-wide rabbet and made the pass. But with the pattern bit already setup, why go through the hassle.
Instead, I positioned the two side panels face-to-face, and also set them front-to-back. I slid one panel over from the edge the exact 3/4″ I needed for the rabbet, clamped the two tight and ran the rabbet, as shown in the above photo. When I cut a rabbet this way, I make the first pass using a climb-cut (that is where I am in the photo). I’m not taking a deep cut, but running down the edge, cutting enough to create a small ledge. I then complete the rabbet running the router and bit in the normal left-to-right cutting pass.
This does two things that are good. One, the climb-cut removes a small amount of the 3/4″-wide waste material – if I were to make a single pass, there’s a chance that I may leave a sliver of waste if I’ve set the rabbet area a bit wide, and it would tax the router setup. Two, and this is a big reason to climb-cut first, the small ledge created acts as a breaking point. By this, I mean if the waste snaps off during the cut, it breaks at the ledge, leaving the rear of my case sides intact – it never splits off the remaining material.
And this is the unexpected benefit. To cut the rabbet on the second case side, I simply flipped and spun around the clamped arrangement. Setting the rabbet for one case side automatically set the cut for the second side, too. After the two sides were again clamped to my bench, I ran through the process a second time to finish the rabbets.
Next time you have a pair of sides to rabbet – large or small – give this setup a try.