Wood – How to interlock 2 pieces of plywood


What is it called when you cut 2 grooves in plywood so that they will interlock with each other perpendicular? What is the best tool for the job? Just a circular saw? A router?

Best Answer

A router with a straight bit or a table saw with a dado stack are the two best options for this task.

A dado stack will be more versatile if you have multiple widths of plywood that you want to work with:

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A straight router bit isn't adjustable in width, but it will produce a cleaner bottomed cut. They're often available in sets for different sizes of plywood:

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If you'd rather not spend the money on either of those, you can always use a table saw with a regular 1/8" kerf blade and make several passes. Then you can clean up the bottom of the groove with a chisel. I wouldn't recommend trying this with a circular saw, but if you do, you'll definitely need to make a straight cutting jig for it.