Quote Originally Posted by Saaglem View Post
Some where, about 10 years ago I've heard, don't know if it is true though, the Americans drilled a hole through a strain of hair, then the Japenees went on and said they cannot top that, so they went and put a bolt and nut in the hole. I'll look for it and post it. NOTE: That's if it was true though.
These stories about microscopic machining abound and are almost universally lies.

A hair's breadth is usually taken to be about 75 um (micrometers) or about 0.003". A hole drilled through would have to be about half that, or 0.0015" which means that, including clearance, the threaded bolt would have to be about 0.001".

The smallest watch screw I've ever encountered is a 0000-160 and has a diameter of 0.060-3*0.013 = 0.021", roughly twenty times the imaginary bolt in the hair.

Color me sceptical.

Today, with a laser, you might be able to drill the hole but the bolt in the hole is not believable.