J-G
Established Member
Clearly the unintended consequence of poor education - or a sloppy attitude to 'history' / 'past convention' !
Allen Socket Screws
- Thread starter niall Y
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Terry - Somerset
Established Member
I thought a bolt was only partially threaded so that in principle it can be inserted in a clearance hole and restrict lateral movement between items being joined, the bolt providing a clamping force only.
A screw by contrast provides a clamping pressure and by friction between the surfaces restricts lateral movement.
It is clear the terms are being used somewhat flexibly!
A screw by contrast provides a clamping pressure and by friction between the surfaces restricts lateral movement.
It is clear the terms are being used somewhat flexibly!
They had a good argument about this over on Quora.
A few interesting opinions were shared but they got no further to agreeing than we have ....
https://www.quora.com/What-s-the-difference-between-a-bolt-and-a-machine-screw
A few interesting opinions were shared but they got no further to agreeing than we have ....
https://www.quora.com/What-s-the-difference-between-a-bolt-and-a-machine-screw
Richard_C
Established Member
I thought Allen heads/keys etc were like Hoovers. I'm going to 'hoover' the floor with the Dyson/Samsung/etc. Allen was a trade name, widely used these days and everyone knows what you mean but really they are hex socket screws, unless of course they were hand crafted by Mr Allen himself. (Don't get me started on Trellis or I will have to mislead you.)
jackcole22uk
Member
TBH, Quora is the last place to find anything apart from opinion.
mcostello
Established Member
Over here a bolt is, 1/4" diameter and bigger. A screw is smaller. How much is threaded has no bearing on the name. It's used indiscriminately. We don't hoover, We vacuum with Our Aluminum vacuums. 
We may have a common language, just uncommon uses for both parties.
We may have a common language, just uncommon uses for both parties.
Robbo3
Established Member
Set screws (or sets for short) are threaded the full length of the shaft whilst bolts are only threaded part way.
This is the terminology used by the wholesalers who get it from the manufacturers.
Both Screwfix & Toolstation use this terminology.
This is the terminology used by the wholesalers who get it from the manufacturers.
Both Screwfix & Toolstation use this terminology.
I have some 10mm diameter coach bolts that are threaded full length. In a similar vein I also have 5mm machine screws that are only partly threaded. Clearly the manufacturers haven't read the memo. 
There is obviously a market for these fixings otherwise they would not exist.
Perhaps the difference between bolts and machine screws cannot be so tidily defined. As an analogy the difference between the colours of blue and green are quite clear to most people When you start mixing them together you will get intermediary colours that some will class as being a blue and other a green. I know this to my cost . I had a customer insist that the 'duck egg blue' her kitchen was painted, was in fact green.
There is obviously a market for these fixings otherwise they would not exist.Perhaps the difference between bolts and machine screws cannot be so tidily defined. As an analogy the difference between the colours of blue and green are quite clear to most people When you start mixing them together you will get intermediary colours that some will class as being a blue and other a green. I know this to my cost . I had a customer insist that the 'duck egg blue' her kitchen was painted, was in fact green.
Often for that purpose you have a locating ring that the bolt passes through or you can use a shouldered bolt with a ground finish.
stuart little
Established Member
I’ve had that colour problem with car paint. I was looking through VW shades of blue colour chart looking for a blue/grey, but found nothing, later I came across it in the 'greens'. I swear to this day that it was NEVER green.I have some 10mm diameter coach bolts that are threaded full length. In a similar vein I also have 5mm machine screws that are only partly threaded. Clearly the manufacturers haven't read the memo.
Perhaps the difference between bolts and machine screws cannot be so tidily defined. As an analogy the difference between the colours of blue and green are quite clear to most people When you start mixing them together you will get intermediary colours that some will class as being a blue and other a green. I know this to my cost . I had a customer insist that the 'duck egg blue' her kitchen was painted, was in fact green.
Incidently, full-threaded coach 'bolts' are coach 'screws'. There are other coach screws that screw into timber (hex head)
Funnily enough in the Welsh language there used to be quite a blurred distinction between blues and greens.' Maes Glas' is translated as 'Green Field' though ;Glas' is now the word reserved for blue.
As for the distinction between a coach screw and a coach bolt. many of the suppliers are referring to their fully threaded bolts as Carriage Bolts, though the supplier 'Kays' seems to be covering all the bases in describing them as: ' Carriage Bolt Cup Square Dome Head Coach Screws' However, I will carry on thinking of coach screws as beefed up woodscrews with a head that can be tightened with a spanner.
.Regarding the coach bolts and coach screws, I scanned two pages from the Nettelefold's 1927 catalogue which illustrates the terms used by this manufacture in their literature. When we order these items, we call the coach bolts, 'cup-square-square coach bolts'. The square actually fits the square hole in crooks and bands used on doors which means the nut is on the inside of the door and can't be unscrewed from outside. When we order coach screws, we normally have a choice of hexagon heads or square heads. The coach bolts now come with hexagon nuts. If we are on restoration work we change these nuts for square ones. We actually have a set of Britool eight-point sockets for use on square nuts.Funnily enough in the Welsh language there used to be quite a blurred distinction between blues and greens.' Maes Glas' is translated as 'Green Field' though ;Glas' is now the word reserved for blue.
As for the distinction between a coach screw and a coach bolt. many of the suppliers are referring to their fully threaded bolts as Carriage Bolts, though the supplier 'Kays' seems to be covering all the bases in describing them as: ' Carriage Bolt Cup Square Dome Head Coach Screws' However, I will carry on thinking of coach screws as beefed up woodscrews with a head that can be tightened with a spanner.
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John Hall
Established Member
As above, you just have to keep looking as not all sellers use the same definition…
I buy a lot on EBay…you need to state fully threaded when you search.
I buy a lot on EBay…you need to state fully threaded when you search.
I’ve got boxes of machine screws and I reckon 50% of them are only partially threaded. Very very rare that I’ve needed anything over about 30mm long that had to be fully threaded. A die helps in these circumstances.
Yeah. On the one hand language is a living thing and new slang comes with every generation of kids. Nothing wrong with that. On the other hand some iliterate moron invents "deplaning" because they never heard anyone say "disembark" and the news media copy them ! Causes a wry smileAn awful lot of people make up their own names for stuff if that don’t know what it is. The Americans are particularly fond of doing this.Wood turners are also pretty good at mis naming stuff but some manufacturers don’t help.
or as my old headteacher used to say "opened their mouth and their brains fell out".John Brown
Freeloading Social media influenza
You can't wash your hands in a bolt.
Standard bi hex sockets also work with square nuts
Totally agree. The phrase “Jam Packed” has been around for many decades until it was reported on the news some years ago about passengers on a train “Ram Packed”Yeah. On the one hand language is a living thing and new slang comes with every generation of kids. Nothing wrong with that. On the other hand some iliterate moron invents "deplaning" because they never heard anyone say "disembark" and the news media copy them ! Causes a wry smile
