Popular Woodworking 2003-04 № 133, страница 42
You do need to use a stop to position the work, because the stop also prevents the bit from moving the work. The bit in a table-mounted router is spinning counterclockwise, and it will pull work to the right. You put the stop on the right to counteract that dynamic. (It's the equivalent of positioning the fence on the right.)
With a Hand-held Router
I'm not ready to entirely abandon the router as a hand-held tool, however. It remains a prime choice for dadoing large workpieces, such as sides for a tall bookcase or base cabinet. It seems easier and safer to move a relatively small tool on top of a cumbersome workpiece than the other way around.
The big question is how you will guide the router for the cut. A shop-made T-square fits the bill, as does a manufactured straight-edge clamp such as the Tru-Grip. An accurate T-square doesn't need to be "squared" on the work, as a Tru-Grip-type clamp does, but positioning it accurately can be a trick.
A setup gauge is helpful here. Cut a scrap to match the distance between the edge of the router baseplate and the near cutting edge of the bit. Align one edge of the gauge on the shoulder of the desired cut and locate the T-square (or other guide) against the opposite edge. Bingo. The guide is set.
Though more elaborate to construct, my favorite dadoing jig is easy to position on simple layout marks, and it adjusts easily to cut the exact width of dado you need. You size the jig to suit your needs.
The jig has two V2" plywood fences, each laminated to a V4" plywood or MDF base strip. Both are matched to a particular router and bit by running that router along the fence, and trimming the thin base with the straight bit. One fence is then screwed to two hardwood crossbars.
Cutting a dado is foolproof.The router is trapped between fences and can't veer off course, regardless of your feed direction. Reference the left fence as you push the router away, reference the right one as you pull it back, completing the cut.
A crossbar attached at right angles to a plywood straightedge makes it an easy-to-align T-square guide for dadoing with a router. Clamp it securely to the work and the benchtop at each end.
Position the jig by setting the fence base edge directly on your layout line. The crossbars ensure it will be perpendicular to the reference edge.