Rethreading screws (the search for replacement screws)

[tonyowen]

oddballs like Whitworth, "British metric", or custom wholly nonstandard., willy-nilly wholly nonstandard screws are more apt to be current Chinese or Indian junk screws,.

Drew,
I think you are showing an unfortunate bias.
The ‘oldballs’ are in fact standardized thread forms that have or had a specific purpose. For instance, pipe, gas, cycle, microscope and instrument threads. Also there are left hand threads, multi-start threads, tapered threads, as well as industry- specific threads.
There are also differences in thread forms - for instance acme – and similar threads but with various pitch angles.
Your ‘ willy-nilly wholly nonstandard screws are more apt to be current Chinese or Indian junk screws’ tend to be cast– hence they do not [cannot] have the precision of machined screws.

Regards
Tony