Comment by WalterBright

Boeing uses inches. Not feet, just inches. The drafting scales (rulers) we used were in inches, but divided into tenths and hundredths of an inch. The ball bearing catalog what in inches, but rather strange values, which turned out to be mm translated to inches.

I had a hard time recently trying to find a scale in inches and tenths and hundredths. It's just easier to user. I'm kinda sorry I sold my drafting equipment.