Woodworker's Journal 1985-9-1, страница 57

Aflat miter joint that is simply butted and glued together will have little strength, so it is generally advisable to add reinforcement, usually with some sort of spline. The keyed miter (see Fig. 1) is a variation of the splined joint that is both strong and attractive — and with this simple jig, it becomes surprisingly easy to make.

Although it can be made somewhat larger or smaller, the jig we show is

sized to accept a fairly wide range of mitered frames. To make the jig, cut a piece of V* in, thick particle board (or plywood) to a width of 10 in. and a length of 22 in. Next, cut two pieces of 1 Vi in. square stock to a length of 20 in. and miter the lower end to 45 degrees. Glue and clamp the mitered pieces to the particleboard, making sure they are exactly 90 degrees apart.

Before using the jig, screw a 6 to 8

in. high auxiliary fence to the regular rip fence. The auxiliary fence will provide additional bearing surface for the jig to ride against. Set the fence so that the saw blade will cut a slot in the center of the mitered frame workpiece. The width of the slot will depend upon the thickness of the stock. Generally, however, you can cut a slot that equals the thickness of your saw blade (usually about Vt in.). For a wider slot, the dado-head can be used, or you can make several passes with the regular saw blade, adjusting the location of the rip fence for each pass.

The blade height should be such that it comes within 1/16 to 1/8 in. of the inside corner of the joint. It should not, however, actually cut into the inside corner.

The miter joint frame you are making must be glued up before it is used with the jig. Apply glue to the mating surfaces, then clamp firmly with a web clamp. Allow to dry thoroughly.

When dry, insert the frame in the jig and place the jig against the auxiliary fence. If necessary, the frame can be clamped to the jig. Now, while holding the jig firmly against the auxiliary fence, push it through the saw blade.

As shown in Fig. 2, the jig can also be used to cut multiple slots in wide stock. Points A and B, on all four corners, are cut with the same fence setting, as are points B and C, W^j