These jigs help you hand cut flawless mortise-and-tenon joints.
By Jeff Miller
Mortise-and-tenon joints tend to frustrate woodworkers far more than dovetails do. That’s no mystery; they are genuinely harder to cut than dovetails. The large flat tenon cheeks and mortise walls need to be flat, smooth and parallel, the shoulders have to line up perfectly all the way around the tenon, and to get a fit that works, the tolerances are within a couple of thousandths of an inch.
About a year ago, I started fooling around with an idea to make hand-cut mortise-and-tenon joints a little easier. I came up with a pair of simple jigs that make it possible to cut – in conjunction with a good tenon saw and some mortise and paring chisels – accurate, repeatable joints by hand that rival those cut by machine. The jigs cut down on layout as well. And they make it easy to cut angled tenons. The final bonus is that the tenoning jig can actually help improve your saw technique.
That all may sound a bit like I’m peddling snake oil, but the jigs are very simple in concept. There’s a jig for paring mortise walls, and for paring tenons, a sort of an upright miter box combined with a system of spacers. There’s no magic involved. There is, however, a fair bit of tweaking the jigs to tight tolerances.
Is it cheating? Maybe. But cheating in the same way that a shooting board is cheating: easy, accurate results on something you could conceivably do strictly by hand. And you still need good saw and good chisel technique to get the best results.
Also, the jigs can certainly be used independently. But they work better as a complete system.
The Mortise-paring Jig
Chopping mortises with a mortise chisel is surprisingly fast and reasonably accurate, but for the best results, it helps to pare the side walls to clean them up. One of the easiest ways to do that and get straight, square results is to clamp a guide block to your workpiece to act as a reference for your chisel. This jig is actually a combination of chisel guides. With it, you can pare both sides of a specific-size mortise located a pre-determined distance from the edge of the workpiece. The jig references off only one edge of the workpiece for greater accuracy. And you don’t need to chop by hand for the jig to work; it will clean up the sides of a mortise no matter how you cut it.
This might seem like a lot of work for a specific size joint, but the jig is very quick to make, and most of the time, you need to cut multiples of the same joint for your projects. Make up one for a table or chair, and it might well do for most other tables or chairs you build.
Video: Watch the author demonstrate his tenon jig.
Video: Watch the author demonstrate his mortise-paring jig.
In Our Store: “Sawing Fundamentals,” by Christopher Schwarz
Web site: Visit Jeff Miller’s web site for a list of classes he teaches.
Article: Read our story on how best to apply glue to a mortise-and-tenon joint.
From the June 2012 issue #197.
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