Woodworker's Journal 2009-33-2, страница 24

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3. Shelving Rabbet "Rightsize" undersized plywood with a rabbet and dado.

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_____ The day will probably never come again where

plywood will be a true 3/4" thick, but that doesn't mean you have to invest in those specialized, undersized plywood bits for your router in order to work

________with il. You don't even have to shim a dado set to

match the sheet thickness. Instead, turn to this simple shallow-shouldered rabbet joint and make that funky plywood thickness conform to your will. Start by cutting the dado side of the joint to the dado width you prefer. As long as the blade's cutting width is narrower than the plywood is thick, you're all set — f/2" or 5/8" works well. Then, clamp a sacrificial fence to the rip fence. Adjust the blade's height and projection to cut the rabbet's tongue so it matches the dado proportions. In a couple of test cuts, sneak up on the precise fit. How's that for taking the hassle out of matching those odd fractions? It's a thrifty, problem-solving joint that works, no matter whal plywood you're using.

The beauty of this joint is that any dado width will work, provided the blade stack is narrower than the plywood's thickness. First, cut the shelving dadoes with a miter gauge or crosscut sled.

Use the same dado stack for cutting the rabbet's thick tongue and narrow shoulder. Set the correct projection and height out from a sacrificial facing clamped to the rip fence (use a featherboard).

With a sharp, quality dado blade, you'll produce shelving joints that fit together as well as or even better than those made with undersized router bits (see inset). Aim for a nice "push" fit. It's okay to reinforce these shelving joints with glue and pin nails or brads.

AN UNDERSTATEMENT.