Re: Hand Tool Question "SAE"
Sometime look up this company that makes taps and nothing but. They can custom make about any tap you can dream about!!! The cost for such is high but they shelf stock some pretty wild ones. MSC has a warehouse about 15 minutes from their factory in PA and does special orders with them all the time. I have a few of their taps that were standard diameters with with wild thread pitches. One is the spark plug size for antique John Deere 2 cylinder engines. It's 7/8-18 with an H4 thread limit size meaning it's 0.002 inches over. For a 7/8" tap that's pretty common. I don't own any older tractors but have helped a few people work on them. This same tap was used for the spark plug in older Gravely 2 wheel garden tractors made before about 1965 or so. That's where I really got to use it.
Reiff & Nestor Co.
Lykens, PA 17048
Phone: 717-453-7113, 800-521-3422 (toll free)
Manufacturer of taps.
Special note: Far too many special dies and taps are coming over from Asia. I detest such and want mine made in North America.