A good machine shop story, I'm a amiture musician, guitar, and mandolin player. A few years ago in Tennessee, the Blue Chip Machine Shop had several pickers working there. They used a very high dollar material to make parts for aircraft, I don't remember the name of this material, but it was similar to the material used to make guitar picks. Some of these guys started taking scraps of this material and making guitar picks from it. They found this worked great, and had qualities they couldn't find in any other material. A salesman that called on this machine shop was also a musician in an popular pro Bluegrass band, the Grascals! They told him about these picks, and gave him several of them. He liked them so well he gave some to other musicians, and before long these picks were in demand! They are called Blue Chip Picks and bring between $35.00 and $50.00 EACH, the last time I bought one. This turned into a very profitable business, and now no self respecting musician pro., or wannabe, would use anything else! This is the version of this story I heard.
OK, gotchya now, seems there's a few explanations here but here is a version of mine, the shop I worked in while with the Air Force we rebuilt F-111 parts, one item was the aileron hydraulic control units which had pistons in them with no rubber o-rings it was an all metal design with a clearance of only .0002" the fit was so close the oil bypass was very minimal, there was no way you could put these together at room temps the pistons had to be frozen in co2 and the cylinders had to be warmed up to assemble them, most aircraft hydraulic pumps are made the same way also, the finish of parts like this are ground very smooth usually to an 8 or better finish. In the case of a couple ground and finished flat blocks it would be the same and it's a combination of fit and molecular cohesion.
A little puzzle for you. How was the nut put on there? The nut is threaded. 
Might be an optical illusion, but I'm going with what I think is obvious just from the pic. the majors on the thread on the left are less, allowing the nut to slide over that end. Barring that, I'd guess a staked nut after it was put on.
Learning to run a lathe is on my bucket list for someday. Super cool.
The threads are the same od from end to end and the nut will travel from end to end.
Is the left OD of the bolt without the threads the same as the right side unthreaded portion?
Is it 2 shafts? Each threaded into the nut from opposite sides?
Nope. But warmer.
Similar threads
