Sounds like a #2 BA
BA Outer
Diameter Threads
per inch Threads
per mm Tap drill
0 0.2362 in / 6 mm 25.38 1 5.1 mm / 7 gauge
1 0.2087 in / 5.3 mm 28.25 1.112 4.5 mm / 16 gauge
2 0.1850 in / 4.7 mm 31.35 1.234 4.0 mm / 21 gauge
3 0.1614 in / 4.1 mm 34.84 1.372 3.4 mm
4 0.1417 in / 3.6 mm 38.46 1.514 3.0 mm
http://en.wikipedia.org/wiki/British_Association_screw_threads Hello SKB,
Many thanks, I'll check it out. If it is a British Association size thread, then it won't be a problem for me to supply the necessary taps and dies. I have most BA sizes anyway. They're still available here in the U/K and commonly used by model engineers so the prices are pretty low compared to the USA. I've also found the reverse to be true with Unified Taps and Dies.
Many thanks, the info is much appreciated.
UPDATE.
The thread has been identified as No.2 BA. Thanks to all for helping.
Harry
