Tuesday, February 11, 2020

Late Monday Mystery... Figure 8 calipers

I was cleaning up in an old barn today, and happened upon this device, the use I can’t even imagine. It’s about 3 1/4” long and opens symmetrically. There are small points in the “jaws” and then the adjustable arm with another point on it. Any ideas, anyone?

Update; see comment from reader "pzak" for the most likely identification. I will talk to a watchmaker contact to see how it might be used.
New update, Feb 27 2020. 
The watchmaker calls them truing calipers. They are used to check and correct any wobble in the balance wheel. The wheel staff-ends are held between the points, the pointer arm is used as an indicator.
Better explanation here.

A different type of truing calipers, with sprung jaws.


Anonymous said...

Some type of thread gage is what it brings to my mind

VectorWarbirds said...

Its a diabolical set of thumb cuffs:)

JP said...

I'm finding a few "figure 8 calipers" used in dental prosthetic work
that look very similar, if a little less elaborate.


pzak said...

Watchmaker parallel caliper? https://www.ebay.com/itm/Antique-USA-E-F-B-Brass-Balance-Truing-Poising-Caliper-Watchmaker-Tool-NT-26-/173873566400

Mister G said...

Thanks, guys! It looks like we've figured it out! I cannot imagine why that would have been located in a barn.

Mister G said...