32nd of an Inch Bolts - History & Lore

Why am I not surprised a Navy contract was responsible?
Or that the Brits are the ones who originated the goofy idea of marking the wrenches by the pitch diameter rather than head size?

It all makes me glad to have been born when I was - I find SAE to be sensible and workable, as well as the unified thread systems.  It's easy enough to understand those and metric as well, now that things have settled down a bit in standardization.

The one oddity I've found in metric bolt sizing is that when you go to the hardware store in the US and buy an 8mm bolt, the head is 13mm.  When you take one out of your Toyota (or more likely lose one and need to replace it!) the head size is 12mm.  I guess Toyota is institutionally superstitious!  Or more likely, Japanese manufacturing rounded differently in their pitch diameter to head size formula.