Tapered sliding dovetail battens

[Brian Holcombe]

They're complete now, once I have some good progress on the overall build I will post it up.

These do not need to be especially heavy, in my opinion, because they will be used in conjunction with breadboard ends.

After building these I came to conclusion that I was over thinking this, the fact is I can knock them with a hammer and further compress them more than season movement would be able to. The major plus is that these were significantly easier to execute than straight sliding dovetails.

[Dennis Aspö]

The tapered sliding dovetail batten is a traditional method used in Finland that dates back to the 1700s. I just found out what it was called in english so I noticed this thread.

The taper was then to make them fit snugly and keep the table top or whatever they where attached to, straight. But this is not new info to you. I just found it interesting I stumbled upon this just as I had learned what it was called.

[Stanley Covington]

Tapered sliding dovetails are excellent. Far superior to plain sliding dovetails. David Wong's post and pictures showing how to cut them are excellent. The same jig can be combined with a well-fettled dovetail plane for increased speed, if the dovetail groove is of sufficient width. But a sharp azebiki, as shown by David, works just as well.

The tapered dovetail does have one potential drawback: With wide swings in humidity, battens attached using tapered sliding dovetails to surfaces subject to vibration (like a tabletop) will sometimes wiggle loose. But with a slight modification, this can be overcome.

I call it a dual-taper sliding dovetail. It is identical to the one David illustrated so well, but the depth of the dovetail groove in the wide surface is sloped along its full length, with the batten slopped to match. It is easy to slope the groove with a rabbet plane, or even a router plane, and a kote nomi. Work from both ends to the middle, checking frequently with a straightedge. The area in the groove underneath the sloped sides is easiest to clean up with a kote-nomi or cranked chisel, in the case of wider boards.



The weight of the tabletop, and anything resting on the tabletop too, for that matter, tends to keep the dovetail locked tight despite vibration or changes in humidity. It also has the advantage of being easily disassembled, and so is especially useful for knock-down furniture, and for some wooden handplanes, which is where I first learned of this very useful and elegant but understated joint.

The one potential drawback of this joint is that, if you fit it poorly, or drive batten and board together with a hammer with too much force, the dovetail groove may split out. Easily prevented with a little common sense.

This is a joint for the advanced woodworker, but once you learn how to do it, you will find yourself using it routinely. Also, it is difficult to imitate with a router, a feature that makes it especially attractive to me. And good kote nomi are just a joy to use.

The first two pics above are of Kiyotada chisels, similar to ones I own. These are based on an especially beautiful design by Chiyozuru Korehide. The last pic is from Dieter Schmid's website. I don't know how well they are made, and am not endorsing them. I was just surprised to find such an attractive set of skewed kote nomi still available, and in Germany no less! Hard to find decent ones here in Japan anymore.

The same job could be readily accomplished with Western cranked chisels too.

Stan

[Brian Holcombe]

Stan, Those are gorgeous! Thank you for the insight and suggestion, since this is already complete I will keep it in mind for future projects.