Mortising on a Router Table
You can make mortises with a fixed-base router mounted in a router table. To make a mortise this way, you have to lower a workpiece onto a spinning bit. It takes a little bit of setup to do this safely and correctly.
You'll need three things for the technique: two stop blocks clamped to the router table fence, and a guide rail to keep the workpiece from kicking out from the fence.
Stop Blocks — The location of the stop blocks is important, so take some time to position them correctly. The idea is to clamp them in place so that when the workpiece is butted against them, the bit is aligned with one end of the mortise or the other (see Illustration).
Guide Rail — As for the guide rail, it's just a scrap 2×4 glued or screwed to a plywood clamp pad (Main Photo). Position the clamp pad so that the workpiece can slide smoothly between the rail and router table fence, and clamp it firmly in place.
Rout Mortise — Before routing, drill a starter hole at the front of the mortise (Inset Photo). This creates a pocket that fits down over the router bit. Then, cutting the mortise is as simple as butting the workpiece against the back stop block, lowering it onto the spinning bit, and pushing it forward until it hits the front stop block. Rout the mortise in a series of progressively deeper passes until reaching the desired depth.
Have a nice weekend,
Online Editor, Workbench