Thanks John. Yes I've come across those charts and have them and I'm actually eyeballing that very set. Another slipped by me last week by a just a few minutes. I've never seen a Waltham set but did see 2-3 taps once in a estate lot that the seller thought they were miniature pin punches. They were in very rough shape. Otherwise haven't seen anything else about american thread pitch or taps and dies for that matter...still lookin.