- Joined
- Oct 10, 2018
- Messages
- 543
I have a 1/2-12 tap, I just don't have the die. The tap is marked "NS" for National Special. The following web page says "The NS series is a catch-all category for threads which have the American Standard form, but whose pitches are not in the National Coarse or National Fine series." As mentioned before, 1/2-12 was _the_ primary standard until the 1920's but was changed to 1/2-13 when the "Unified Series" thread standard was ratified.
Craig
I've also got a 1/2-27 tap! Gotta love auction box lots!!
American screw thread gauges
American screw thread series, with diameters of clearance holes, size of tap drills, and size of nuts.
www.sizes.com
Craig
I've also got a 1/2-27 tap! Gotta love auction box lots!!