Re: Last time this happened...Also I call them bolts.
Oh dear, typical Vogon never wrong...
I used the term "screw thread". That's what they are called. Bolts, studs and machine screws all have screw threads.
Generally a bolt is something that screws into a nut, i.e. it has a head at one end and a separate nut at the other.
A machine screw is like a bolt but is designed to screw into a threaded hole in a piece of metal. I suspect that the fasteners of an Airbus windscreen could well be machine screws.
A stud has a thread at both ends and usually a non-threaded bit in the middle. One end screws into a piece of metal; the other end takes a nut. Cylinder heads are usually held down with studs. Rocker covers are usually held down with screws. Thin pieces of metal are usually bolted together as there isn't enough depth in either piece to thread it.
I completely fail to take your point about the size of the head. Usually standard screws (or bolts, to keep you happy) have a given head size for a given thread diameter. The reasons for this are (1) to keep the number of spanner sizes sane and (2) because there's a relation with thread diameter and shearing force, so the head size should ideally reflect the flats or whatever being of a size to resist the maximum safe load while not being so big that a slightly clumsy mechanic will keep shearing heads off.
There also tends to be a limited range of pitches because if there isn't enough difference sooner or later someone will try to insert a 0.95mm pitch thread into a 1mm pitch hole using BFI, and this will not be good.
Mine is the one with the copy of Machinery's Handbook in the pocket.
Biting the hand that feeds IT
