Woodworker's Journal 2004-28-6, страница 40

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Spiral-flute bits produce superior cuts in a wide range of materials because their cutting edges are in continuous contact with the workpiece, slicing through the wood fibers at a shearing angle. In contrast, the cutting edge of a straight-flute bit contacts the workpiece intermittently and cuts into the entire width of the workpiece at a right angle. If the depth of cut and feed rate remain the same, more flutes will produce a better cut. That's why many woodworkers use end mills, a type of spiral-flute bit popular with machinists. They are commonly available with four

flutes — and longer flute lengths.

Start the Jig Construction

There are two parts to make; the table and the fence. The width of the table is determined by the amount of desired work surface, plus the diameter of the router base and the overhang for the clamping system. Eight inches of work space is adequate for me. My router has a 6" diameter and I want at least 6" of overhang... anyway, I ended up at 15".

Rip the table to its width and then measure 28" from the light end and 3³A" in from the back edge for the router bit hole. Mark and drill the holes to mount the router base at the location of the router bit hole. Mount it so the tightening system is facing the front. Drill a 1/2" hole for the router bit, and chamfer both sides.

Now rip the two rails to exactly 2". Make the cuts dead straight or the router-jointer jig will be twisted when you clamp it down, and you won't be able to edge joint at 90°.

Attach the rails to the bottom of the table with glue and brads. Be sure to countersink the brads so they can't mar the wood being jointed. Use a block plane to slightly chamfer all the edges to make the jig "splinter-free."

Rip the fence bottom and fence face. Mark the router bit recess al 28" from the right end and l'/s" up from the bottom edge. Drill a 5/8" hole. Mark two lines tangent to the hole and perpendicular to the bottom edge. Carefully saw along the lines creating the U-shaped bit recess. Sand the sharp edges smooth.

Drill a 1/4" hole 2" in from the right end of the fence bottom and a 7/16" hole 2" in from the left end (foi* fence adjustment). See the Drawings on the previous page for details.

Glue the fence face to the fence bottom. I used brads to hold the two pieces while the glue dried. Again, be sure to countersink the brads. Glue a piece of high pressure laminate to the outfeed surface, extending from the bit recess to the end. Flush trim the laminate so no edges extend beyond the fence edges. Freshly cut laminate can slice your fingers, so file the edges smooth

The author checks out a tight, clean joint machined on her router-jointer jig. No muss, no fuss.

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to ease any sharp corners. Place the fence on the table in its proper position and use a pencil to mark the spots where you'll drill 1/4" holes for the carriage bolts.

Using the Jig

Fasten the router base to the bottom of the table. Install the cutter in the router. Raise the cutter to extend above the thickness of the wood youll be jointing. Flip the table over and clamp it down. Now turn the bit until a flute is presented to the widest cutter arc. Tighten the fences' right knob, then rotate the fence forward so the bit is fully inside the recess. Place a straightedge firmly against the outfeed surface and carefully rotate the fence until the emerging bit just touches the straightedge. Tighten the left knob to lock the fence into final position. Because this setup guarantees that the cut equals the thickness of the laminate, the edge of the workpiece will be fully supported by the fence during the entire cut as it passes from the infeed surface to the outfeed surface, and the edge will be straight With the router on (use eye and ear protection), place the wood face down on the table and move the wood from the right to the left against the fence. At the start of the cut, hold the wood firmly against the infeed surface, gradually shifting pressure to the outfeed surface as the cut progresses. Repeat the operation until the edge is completely jointed. Try a test cut for straightness, and check for square as well. Squareness is not usually a problem because it depends on the router base and its relationship to the bit. If it is a problem, check that the base is firmly attached to the table bottom. One other point: if the face of your stock is not flat or is out of winding, your edge will be out of square ... it is always best to check, just to be sure. fa ____/

Carol Reed is a teacher, a furniture designer and the author tf/Router Joinery Workshop, available from Lark Books.