Originally Posted by
fredvon4
I am not a Cox historian but have a question
What make you believe a 4-40 was more common in 1940s?
And do remember......if a customer needs a special part that you sell....modest price increase for the convenience is translated to profit...something every good business desires and needs
I don't know that 4-40 was more common for a hard fact but do have the observation that most of my old junk, old radios, cars, tools etc. tends to use the No 2, 4 and 6 screws. The only place I've ever run into No 3 or No 5 screws is in regard to model airplanes. It is just kind of a random interest in industrial history. Old guns often seem to have screw threads that you don't often see elsewhere and if you play with little British cars you should plan on investing in fine thread or even whitworth screws and bolts. I'm just wondering if early on there was a specific reason for the 5-40 screw or if one of the early 1/2 a engines had that thread and everybody else just followed that as a matter of convenience.