On May 2, 12:04*pm, aemeijers wrote:

snip

Engineers that use
SAE heads on metric bolts, or vice-versa, should be shot.

Not sure if we should blame the engineers. A lot of those mongrel
combinations are Asian, mostly Chinese in my collection. I think they
feed their screw machines with metric hex stock, so the bolt heads are
never 5/8", for example, but 19 mm would be just fine with a 3/4"
socket.
Worse yet, years ago, was working with British Whitworth. Hardly
anything was a standard measurement. Old timers that dealt with MG
TC's and TD's will remember the frustrations.

Joe