Odd wrench identification

[Luked]

Found this guy in my grandfather's old tools. It's stamped 1/2 SAE and 9/16 but both ends are much larger than the stamping.

 

[PartsGuy]

The stamping refers to the thread size of the fastener, rather than the hex size of the fastener. Apparently that was a common measurement method back in the day.
I ran across one last year and asked the same question!

 

[Luked]

Wow, “today I learned” any ideas on age?

 

[L.Cheapo]

British Whitworth was like that. The size on the wrench was the size of the thread, not the opening of the wrench.

 

[BOOT]

I got a few old wrenches, LOL good to know they aren't wrong but just diff back then.

 

[Sevenhills1952]

1/2 Whitworth and 1/2" combo

Sent from my SM-S320VL using Tapatalk

 

[PartsGuy]

still getting used to the BS/Whitworth measurement convention, it just feels so wrong after years of SAE....