On 22/10/2020 14:48:57, Andrew wrote:
On 22/10/2020 08:27, michael adams wrote:
A bolt is threaded into a nut to tighten it,

A screw is threaded into a female thread, or as in the case of woodscrews
creates it own female thread.

Is a cylinder head bolt, a bolt or a machine screw ?.

In the UK it would be a bolt. In other countries it may be a screw.

This link may help to understand the USA vs UK nomenclatu
https://www.accu.co.uk/en/p/131-diff...rews-and-bolts

Interesting point about bolts and screws in that the USA had some
historical differences in taxation. Such classification will always
introduce distortions and confusions.

Another example of this kind of distortion:
https://en.wikipedia.org/wiki/Screw
"Reasonably, these fasteners might be referred to as bolts, but based on
the US government document Distinguishing Bolts from Screws, the US
government might classify them as screws because of the tighter tolerance."

Be careful as wiki is very much USA centric.

For the UK, it's simple. A bolt is a fastener with a portion left
unthreaded. A machine screw, or set screw is fully threaded.

If you ask a UK supplier for a bolt you will get a partly threaded
'bolt'. If you ask for a machine screw or anything with "screw" in its
name, it will fully threaded.

YMMV + I am sure there are exceptions! :-)