Cleaning up around the shop I found this odd tap. It's 10" long and is stamped P B & N CO 3/4 with a little 1/32 next to it. My thread gauge says a perfect 10 TPI It' oversize cause I can't run it on a regular nut. What could be it's use?
likely for galvanizing . philip
Might be for putting stay bolts in steam boilers,