The jig is made up of two types of slats: the router guide strips and the two slotted baseboards. The plans show how these components are configured into a rigid combination by tightening down locking knobs on their T-bolts as the jig straddles your workpiece.
When you're configuring the jig, grab the piece of wood that will ultimately fit into the dado (I'll call it the “shelf” for clarity), then use it as a spacer while you position a guide strip tightly to each side of it. Tighten the knobs with the shelf between the guide strips, then get ready to rout.
Adjust the height of the flush-trimming router bit so its bearing rides against the inside edge of one of the guide strips as the router slides over top. The cutters must also extend down deep enough to create the depth of the dado or rabbet that you want-typically, 1⁄4" to 3⁄8". The dado engine requires a router bit that's somewhat smaller than the width of the groove you want to cut. The bit should not be less than half the width of the groove because each dado is cut in two passes.
During the first pass, the bearing of the router bit rides on the other guide strip. Since you used the shelf itself to position these guide strips while you configured the jig, they'll automatically guide your router bit so that it creates a groove that matches the thickness of the shelf perfectly.
Build Up
Start by preparing as many router guide strips as you want, using 3⁄4"-thick cabinet-grade plywood. You'll need two guide strips for each dado/rabbet groove that you want to rout at once with a given set-up. I made three pairs. The length and width of these strips is up to you. I made mine 4" wide and 36" long. These dimensions create a lot of room to support the router during use and allow me to cut grooves across pieces of wood as wide as 24". Make your guide strips wider or longer than these, if you like.
Regardless of guide strip size, mill a groove down the middle of one face for the aluminum T-track that is key to the system. I secured mine with polyurethane glue.
You'll also need to make two slotted baseboards. Each one includes two strips of wood with a 5⁄16" slot between them, held together with end caps secured using #20 biscuits and glue. The slot between these strips must match the diameter of the T-bolts you're using-mine are 5⁄16". Sand the wood, round the corners slightly with sandpaper, install T-bolts and knobs, and you're ready to go.
1 Comment
In regards to the video clip on creating dados, the sound was coming through, but the picture was not playing. Cheers