Exact Width Dado Jigs

Two simple router jigs to get perfectly sized dados and grooves, even for undersized plywood.

- Willie Sandry

The ability to cut perfectly snug fitting dados and grooves is one of those fundamental skills that will catapult your woodworking into the realm of cabinets and fine furniture. Sure, you can cut accurate dados on the table saw with a stacked dado set, but that’s a real challenge if you have large workpieces or stopped dados. A bookcase, hutch, or cabinet project may leave you wanting an alternate way to cut dados.

The concept of an exact width dado jig is pretty simple. Just use the actual shelf stock you intend to use for your project as a thickness gauge to set up your jig. From there, you can rout the groove and expect perfect fitting dados each time … even if your project includes 3/4" plywood that actually measures 23/32" or some other odd dimension. These jigs aren’t new, and I’ve been using one for the better part of a decade with predictable results. My first jig used a short-length bearing-guided bit, but you can also use a guide bushing, as long as your jig design accounts for the off set between the bit and bushing. So, I came up with a design that can be built for either style of dado jig and made sure to include some creature comforts like ‘finger grip’ openings to help close the jig on your shelf material and sliding stop blocks. Both versions provide zero clearance to protect delicate plywood veneers and will have you making perfect dados in no time. Choose the version that best fits your shop or make them both!

Build Guide Bushing Jig