Old Plug Tap

[Paul Aslanides]

Found this old plug tap years ago, never had to use it. The thread gauge says it's 27 Threads per inch.
The major diameter is 0.405 inches (10.29 m/m) approx. I figure it's a 1/8 x 27 NPT, National Pipe Thread, American standard.
It has the square tapered end, to go into a Carpenter's Brace, though I reckon it would be fun starting it squarely into an existing thread as there is no taper whatsoever on the business end. Perhaps it was started by hand, then the brace put on. Can't see any stamps or marks on it. Anyone familiar with these ? Thanks.

 

[Beerhippie]

Thread restorer rather than a tap?

 

[Paul Aslanides]

Thanks for correcting me. Yes, no doubt it would be used to clean up rusty or damaged threads, more of a thread chaser than a tap. Cheers.

 

[Provincial]

7/16-27 thread is used on some air-powered grease gun hose connections.

1/8-27 straight thread was used on older electrical piping, and some instrument connections. These are .405 outside diameter, just like 1/8 npt.

 

[Paul Aslanides]

Got it. Thank you.