watchmaker got this in a box of tools he bought. Wants to use it, but WHATISIT

#2

#3

Believe that its a rev counter.. I have one around here that is similar. Its used to accurately determine the revolutions of shafting, wheels, and spindles in either direction. There should be a rubber points which would be pressed against the shaft or spindle.

That's right. I think they were used on lathes to help determine revolutions.. as Wayne said.

Old time machinists used them. I don't know if they are used today, except maybe in non-CNC shops.

From Starrett catalogue 1976

peter