Presumably it's a single dovetail, running at 45° across the square.

… unless, of course it's a neat bit of inlay work

MichaelG.

How about two dovetails in the form of a cross and a very large hammer?

Err, no!

[Sorry, I could not resist it]

JA

Edited By JA on 29/01/2016 19:45:58

For those that want to know how to make one. This video will explain… https://youtu.be/a3V42KwLTeE

Graham

Back when I used to write for Model Engineer I wrote up how to make one of these. Mine was done on a shaper since these are a good machine for doing dovetails without fancy dovetail cutters. The usual approach is the two dovetails at 45 degrees to the faces. You can also make them by setting up each block with one corner along the axis of the lathe and making the dovetails on each part as a quarter circle, then as Robert described above they twist in together. Either way the work wants to be accurate and close fitting, or else it becomes easy to see how it works.

I first saw this idea as a woodworking exercise in either Popular Science of Practical Mechanics back in the late fifties or early sixties, but would assume it is much older than that.

John

A bit like this. Cut by hand from huon pine. I only had a saw, a chisel, and a couple of files. Very laborious!

Edited By Sam Stones on 31/01/2016 04:22:34

Edited By Sam Stones on 31/01/2016 04:22:56

What it looks like now, but no spring-loaded detent.

Fusion challenge part 2 – sliding version.

Murray