Many moons ago, although surprisingly still in pandemic times, I made a small sitting bench out of scrap pine (Eastern White Pine for the top and Red Pine for the legs) that used angled, rectilinear tenons and a cross-rail on each end. After watching Grandpa Amu make a new workbench several times, this was an experiment and study in how these sorts of angled tenons work. The legs splay out at 10 degree (ish) angles, but have no rake. At the time, that seemed to me a good first step and was actually doable without any guides or other jigs. Just a chisel and a bevel gauge and some caution.
Shortly after that, I took a six foot piece of 8″ wide clear vertical grain douglas fir that was languishing in the lumber pile and turned it into slab top and four square legs for the next part of the experiment. Which then sat, leaned up against the wall, for almost a year. But the spirit moved me this weekend and I got back to it. For this piece, the legs would have both splay and rake (both at around 10 degrees). And it’s worked out nicely (and not just because CVG douglas fir is very handtool friendly).
Shortly after the original experiment, I made a couple of test mortises (also in Eastern White Pine) using the same technique as the first bench (freehand with only a bevel gauge to assist). They didn’t come out great, with the bottom of the mortise (on the underside) being wider than the top. This led to inconsistent leg angles that couldn’t be wholly attributed to the softness of the EWP top.
So what I did instead was cut a few angle guides from squared up 2×4 (more on that in a future post). That way, I could freehand close to the lines and then, in a final paring cut using the guides, get the angles dead on. At least within appropriate tolerances for a piece of furniture. I’m no machinist, after all.
So was it strictly necessary to go through all this fuss to make the angles perfect? Probably not. I’ve already drilled the peg holes into the top and this will live as a saw bench in my shop (replacing a pair that are about 6 years old and wearing out quickly). It didn’t need to be perfect.
But if I were to use a joint like this in a proper piece of furniture, I think the angle paring guides are the way to go. Could I eventually get good enough freehanding to not need the guides as a crutch. Sure. But that’s a lot of work and, in my view, if a simple jig works, it’s worth using.
And, for now, I’ll gladly use whatever help I can get.