
Mystery compass/divider
Does this nice little compass/divider that I found in a thrift store ring any bells for anyone? It came in a plastic clamshell for a Uchida KD-Type .05 microsharp compass, which is certainly is not. It's quite solid and well constructed, very satisfying to hold. No maker's mark or country of origin. No logos. Nothing stamped or engraved on it at all. Image searches on Google and Ebay find tons of wrong (often spectacularly wrong) matches, but I haven't see one yet with a similar lock/release mechanism. The lobed plate jutting out from the hub has a spring under the wide end, that when compressed with your thumb lifts the other end, which acts as a brake against the hub. Push it down and you can move it freely. Release, and it rigidly holds its position.
I kind of suspect it might actually be a hand/machinist made one-off, but if so, the execution is excellent. Unless somebody recognizes the design, it might even be a prototype or a patent model, but that's just wild speculation based on not much of anything. Any information would be appreciated.