The Mortise Jig

by Patrick Harper - Blood, Sweat, and Sawdust

The Idea

Above everything, I want to create beautiful and unique furniture.  The furniture which draws my attention has a common theme: mortise and tenon joinery.  Ideally, I would create mortises with a dedicated hollow-chisel mortiser.  Unfortunately, I don’t have the space or funds available for such a wonderful tool.  As a result, I have determined that my best course of action is to use the plunge router for mortising.

To improve speed and accuracy, I followed Jeff Miller’s advice and built mortise jig.  I followed Jeff’s design fairly closely, but made some minor improvements to the original plan.  For example, I added a t-track and adjustable stop blocks for better repeat-ability.

The Design

The jig is simple in design and easy to make.  It consists of a platform, a track, and a pair of hold-down clamps.  I milled an auxiliary fence for my router at the same time I milled the parts for the track.  This ensures a perfect fit to guide the router.

A 8/4 white oak board with too many knots for furniture sat on my lumber rack.  It had just enough straight grain to mill up the parts for the jig.  I laminated two pieces to make the platform.  Then, I cut a dado for the t-track.  I built the guide by resawing another strip of oak.  The resawed pieces produced three 3/4-inch strips: two for the guide and one for the auxiliary fence.

I glued the guide pieces together.  However, I did not permanently attach the guide to the base.  It attaches using 3/8-inch bolts that are also used to secure the hold-down clamps.  This allows me to replace the track if it wears out over time.

The Results

I eased the sharp edges with a block plane, and applied paste wax to the fence.  So far, the jig works extremely well.  I plan to use it on a few projects that I have coming up.  Stay tuned.