Mitered half laps are a great joint to use in woodworking because they are a very strong joint, and also have the decorative mitered face, but there is not any jigs on the market that allow a user to accurately and repeatedly make these joints on a router table.
I took this project over from another designer on our team. He gave me a solid starting point and passed along all his research. I began by continuing the direction he was going, but we ran into a problem. All the designs we had produced had the jig riding off the fence of the router table, and this made repeated accuracy very difficult to achieve.
I went back to the drawing board after making probably a few hundred frames, and decided to have the jig ride on a miter bar, which would give the jig a much more consistent offset from the router bit. I then looked back at some of the ideas that my teammate who was working on this before had and found some good ideas to work off of. I decided to have the workpiece rest against a pin system that would make accuracy and micro adjusting the jig much more possible.
the sacrificial fence on the jig mounts in 3 positions, the front of the jig has a zero clearance to make reference easier, and there is a center finder in the clamp block that allows the user to make reference marks on their workpieces.
The key to the jig's accuracy is the set screws in the pins that are micro adjusted on the jig's first set up to get perfect accuracy.
Rockler Half Lap Router Jig

This is a first of its kind router jig that allows a user to rout half laps and more importantly mitered half laps on a router table. This product required a very extensive amount of testing and prototyping to get right. When this project started another designer on our team was the primary designer and his research and testing gave me a solid starting point. Everything you see here is from the point that I took over the project. Like all Rockler products in my portfolio, while I was the primary designer, getting the project to this point was a team effort. This one was particularly challenging because based on our research nothing like this existed, especially nothing that could cut the mitered half laps on a router table, and this is a fairly advanced joint in woodworking that requires a high level of accuracy on the steps before even getting to the router table.

Jay Owens
Industrial Designer Minneapolis, MN