Super-strong mitered half-laps
Loads of glue surface area make a half-lap one of the most durable miter joints you can make. Thanks to a couple of easy router-table jigs, you'll be cranking out mitered half-laps quickly and accurately.
Rail and Stile routing jigs
Start by machining your frame stock to thickness and width. Assemble the rail routing jig [Drawing 1] and the stile routing jig [Drawing 2], designed to work with 2"-wide frame stock. For a different width, customize the rail routing jig by making the fence overlap and the slot between fences the same width as your frame stock, shown in photo below. Then adjust the stile routing jig by making the fence overlap exactly half the width of your frame stock.
Cut the frame stiles and rails to the final height and width of your frame, mitering the ends of the rails only. Chuck a 1⁄2 " straight bit into your table-mounted router and set the bit's height to remove half the thickness of the rail and stile stock. Then follow these four simple steps to set up and cut the mitered half-laps.
4 Easy Steps to Tight Miters
Step1: set up for the cut
With the base of the rail routing jig against the bit's cutting edge, lock the fence against the jig. Clamp scrap stock in the jig and make a test cut by running the jig against the fence. Advance the stock for subsequent cuts.
Step 2: stack the stock up
Rout test half-laps on two pieces of scrap frame stock and check the height by stacking the half-lapped stock on a flat surface, as shown. Dial in the bit height until the tops of both scraps are perfectly flush.
Step 3: Use the rail jig for mitered ends
With the bit height set, clamp the mitered rail stock face up in the rail routing jig for the first cut, as shown. Advance the rail and repeat until the mitered tip of the rail touches the router fence for the final cut.
Step 4: Use stile jig for straight ends
Reset the router fence for the stile jig as you did in Step 1. Clamp the stile against one of the fences, face down, and rout the half-lap with multiple cuts. Use the opposite fence to rout the other end of the stile.