There’s always more than one way to go about any joint. I thought I’d share my preferred method for fixed shelves and drawer dividers in casework. I’m sure you can rollover some of these ideas into solid wood casework, but I’m speaking primarily to the times we might be using cabinet grade plywoods.
I should also note that routers and their partnering jigs are very effective for dados, I just like using a dado stack in the tablesaw when I can. Mostly because of familiarity and speed.
So, when I make dados in plywood casework, I always rabbet the mating piece. like this:
Several reasons why:
1) Frustration. Have you ever wasted a bunch of time with the your tablesaw dado stack attempting to get the exact width of sheet goods? Just when you find the proper combination of cutters, shims, etc, you’ll switch types or even brands of plywood and it’ll be different. Maddening, and a waste of time.
2) Speed. Just slap together a few cutters in your dado stack to equal approximately half the thickness of the ply your using. Usually 3/4” ply, so about a 3/8”. You’ll make a custom rabbet anyway. Mark and cut the dados.
I also recommend knifing the line. This will help with chipout on the fragile veneer.
3) The Cover up. Now, even with knifing, I got a little chipout on the “open” side of my dado blade (hope you can see it on the right side). That’s where the beauty of the rabbet comes in. It will hide the chipout. Here’s the made joint:
4) Fit. To make the rabbet, I use an auxiliary fence on my tablesaw, like this:
I can raise the blade slowly on test cuts until I get the right thickness on the rabbet. Of course I can always finesse the joint with a block plane.
5) Strength. I’m sure some would argue that I weakened the joint by thinning the “tenon” of the joint with a rabbet. Maybe if your going to jump up and down on it. I would argue that I added more glue surface and possibly increased the lateral (side to side) strength of the joint.
Anyhow, that’s how I does it up in my shizzopp. I can toss together a case like this in short order with this process.
Hope it makes sense. Shoot me any questions you might have, Red
-- "At the end of the day, try and make it beautiful....because the world is full of ugly." Konrad Sauer