DeaconSteve
Active member
I think this may be an early form of a machinist square. Am I right? The two knobs on the front unscrew and the round face opens up enough for a machinist ruler to fit through and stick straight up. What is the purpose of this type of design compared to the modern machinist square? How common is this tool now? I have only found one on a search engine, and the poster did not know what it was used for.