Thank you Joe for your interest and explanations I have many Model engineering friends as serious as yourself and I am sure that Brian was not as across the situation here in Australia since we went Metric so long ago. The Penmaking industry uses threads that are required if you want to make your own kits but if you want to use existing parts to construct the whole thread matching is essential.
I remember clearly out on the runway at our airport soundly cursing metric to high heaven when a French manufactured runway light was bowled over (French fittings were the go because of their domination in the industry with Fresnel Glass) fingers raw in the deep frosts and aeroplanes circling running low on fuel the Strouger Relays controlling the light systems on the fritz. As a sparky as Brian said BA and so many bastard threads were the norm. Sophistication for techs in threads and threading was hit and miss.
Penmakers fall into many catagories one called advance deal with threading their own pen parts.
Me I am grateful for all information Brian I got my latest death sentence on last Monday yet to get the sentence the verdict is now in.
Thanks Joe Brian whoever for proper defined engineering based info that helps us navigate the dark waters of threading and why.
I imagine in the UK with your next door Metricated Europe from whenever the thread discussion has existed for ever.
Kind regards To All. Peter.


