If glue could create a perfect bond between pieces of wood, there would be no need for anything other than simple butt joints.But since adhesives will probably never get that good, woodworkers everywhere have developed ways of using interlocking connections to help glue do a better job. And by far the most popular of these are the rabbet and dado joints. Behind these weird names you’ll find nothing more than simple grooves. The dado has three sides, and the rabbet has two. Adjoining pieces of wood interlock with these grooves, substantially boosting the surface area of the joint and its load-bearing capacity.
The dado groove (top) has three sides and is being cut with a hand-held router following a guide. The rabbet groove (bottom), can be cut with a table-mounted router or a table saw.
But as simple as dados and rabbets seem, there are tricks to producing them accurately and efficiently.And the best approach depends on whether or not it makes sense to move the work piece over the tool or the other way around. Both the router and table saw are ideal for winning the dado-and-rabbet challenge. A hand-held router is best for cutting dados across the sides of a bookcase, cabinet or in any other situation where the work piece is to big or awkward to push over a table saw or router table.
任何一个Dado槽的多年生问题之一是宽度达到所谓的标准厚度的胶合板。Cut a dado groove with a 3/4” diameter router bit and you’ll almost certainly have a too-loose joint when you try to plug some 3/4” plywood in place. Under the guise of metrification, sheet material thicknesses have all shrank enough to cause problems with joinery if you rely on the old, Imperial thickness designations. And besides, material thickness varies enough from sheet to sheet that it can make a difference when it comes to prominent joinery. This is even true in the USA that still uses Imperial more or less exclusively. Sheet goods remain thinner than their name specifies.
定制精确Dados的一种方法是两次通过，使用手持式路由器在夹莱坞夹具内夹紧到您的工件内。This is especially effective when making bookcase or cabinet sides. Build the jig for use with a particular router base, sized so the jig’s side strips only allow the router to cut a groove that precisely matches the dado width you need. Simply chuck a narrower-than-the-dado straight bit into your machine, then make a pass along one side of the jig, then another pass down the other. When preparing dados to accept pieces of solid wood shelves, cut the dado first, then use a thickness planer to custom-mill the shelves so they fit just right.
Click below to download free plans for building my Dado Engine jig.It lets you safely rout dado grooves for cabinets and shelves with the perfect width of groove to match your sheet material.