Difference Between Bolts And Machine Screws

Hi,
I was wondering if you could clear something up for me....as per the subject....what's the difference?
Is it to do with the thread length IE a machine screw is the whole length
where as a bolt is only a fraction of the length?
Cheers,
Michael
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in message

Chris
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Wikipedia told me that machine screws have thread on the whole length, but it didn't specify what is classed as a bolt - so I figured it may be something to do with the thread length.
Cheers,
Michael
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On Tue, 03 Jul 2007 19:20:39 GMT, "Michael"

I've always called them set screws (fully threaded length) rather than machine screws. Conversely, I've always thought of machine screws as rather small diameter set screws with a c/sunk head.
Peter
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On Tue, 03 Jul 2007 22:35:38 +0100, Peter Neill

They're only for *small* machines <g>
Big machines need big machine screws. I don't think they need to be countersunk, they can have round, pan, whatever, heads.
Tim
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Michael wrote:

That's what I thought. I think we're basically right, but another common definition seems to be that a screw is intended to screw into a part, whereas a bolt is designed to be usee with a nut. Like most things, it can get much more complicated.
This page <http://www.boltscience.com/pages/faq.htm says that some very short bolts can have threads all the way to the head.
There's even a 21 page document to help US customs decide whether to use the duty rate for bolts or screws, which are apparently different!
<http://www.cbp.gov/linkhandler/cgov/toolbox/legal/informed_compliance_pubs/icp013.ctt/icp013.pdf
Dave
(Yes, I was bored)
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I suppose we should approve of customs officers and other subterranean life-forms being given pointless 21-page documents to try to understand.
From my earlier career, I must say I found customs duties even more stupid and pointlessly complex than VAT, and that's saying something.
David
--
David Littlewood

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