Non metric screw.

[Gary]

Any idea where I'll get some 1/4" 20 3/4" cap head screws?

It's the thread tpi I'm struggling with.

They're for a Jessem legstand if it helps.

 

[MikeJhn]

I have always found e-bay to be the best for cap head's always buy SS ones, you know it makes sense.

Mike

 

[sunnybob]

In the UK thats known as an Allen bolt.
Might help you find some.

 

[MikeJhn]

Very true, but for some reason they are all capped cap head screws on e-bay, even though they are a bolt as you say, its all these American words creeping into the English language, as George Bernard Shaw once said "two countries divided by a common language."

Mike

 

[Doingupthehouse]

You could try here, I've used them and they're very quick to deliver.

http://namrick.co.uk/acatalog/Imperial_ ... crews.html

Cheers
Simon

 

[Gary]

I can find UNC, UNF, BSW but the way I'm reading it the bolt has 20 tpi. What does that convert to?

 

[woodpig]

1/4" Whitworth is 20 TPI. If it has a hexagon socket the correct name is Cap Head Socket Screw. You can also get Button head or Countersunk socket screws.

http://www.ebay.co.uk/itm/BSW-1-4-Whitw ... BA5KZDWdyw

 

[sunnybob]

1/4" is 6mm. Buy a 6mm allen bolt and re-tap the thread in the leg.
20 TPI translates to 1.27mm and theres no such animal. Metric fine (as used on motorcycles) is 1.25mm, so if it was me I would just force the bolt in or, just drill the hole bigger and use an 8mm bolt and nut.

 

[woodpig]

I don't use imperial fasteners but I've just checked and 1/4" UNC is also 20 TPI.

 

[Gary]

I don't use imperial fasteners but I've just checked and 1/4" UNC is also 20 TPI.

I don't usually.

Thanks for that I'll try 1/4" unc and run that size tap through first.

 

[nev]

Handy chart about halfway down this page
http://www.baconsdozen.co.uk/tools/conv ... charts.htm

if i read it correctly 1/4" 20tpi will be either BSW or UNC

HTH

edit

unc suppliers
https://www.westfieldfasteners.co.uk/UNC.html
bsw suppliers
http://www.thomassmithfasteners.com/hex ... s_bsw.html

 

[Hemsby]

Can cause confusion sometimes #-o

A bolt is only partially threaded. A screw is fully threaded.

Slight variation is that bolts under a certain length (usually about 1inch long) are also called screws

 

[sunnybob]

Till the day I die, that will be an Allen bolt, americans be dammed.

 

[Duncan A]

UNC and BSW have the same TPI up to 7/16"; starting with 1/2" they are different. There are slight differences in thread profile, but not enough to matter in normal circumstances.

By the way, 1/4" is 6.35mm, not 6mm. If you wanted to convert a 1/4" tapped hole to a standard metric size, you would need to enlarge it to 8mm.

And as for Americans, I'm afraid that William G. Allen of Allen key fame was American as is still the Allen Manufacturing Co. Can't get away from the Murricans I'm afraid! FWIW, I've always found the genuine item to be among the best hex keys out there.

Duncan

 

[woodpig]

Bondhus make probably the best Hex keys, they even supply NASA.

https://www.electronicfasteners.com/wp- ... atalog.pdf

 

[MikeJhn]

Can cause confusion sometimes #-o

A bolt is only partially threaded. A screw is fully threaded.

Slight variation is that bolts under a certain length (usually about 1inch long) are also called screws

That may well be your understanding, but the reality is a partially threaded bolt is called a shanked bolt, a screw is pointed and you use it to screw into wood, all threaded units that take a nut are called a bolt, damm Americans have confused you as well, I am old enough to remember when this was very clear to everyone in the UK.

Mike

 

[RossJarvis]

Very true, but for some reason they are all capped cap head screws on e-bay, even though they are a bolt as you say,
Mike

Being a mega pedant I need to point out that if it has a screw thread it's a screw and even manufacturers get caught out, you can bolt something together using a nut and a plain shanked, hex headed screw. Bolt is a verb, so horses bolt, however something you slide across to lock a door can have the noun of "bolt" but this is because it is a machine used to "bolt" something (oh, maybe crossbow projectiles may be bolts, noun). Most things called bolt are just types of screw........ These days I find myself to be in a minority of about two in this matter though :x In engineering circles the bolt/screw definition thing is the equivalent of sharpening regards angry disagreements.

 

[Hemsby]

Can cause confusion sometimes #-o

A bolt is only partially threaded. A screw is fully threaded.

Slight variation is that bolts under a certain length (usually about 1inch long) are also called screws

That may well be your understanding, but the reality is a partially threaded bolt is called a shanked bolt, a screw is pointed and you use it to screw into wood, all threaded units that take a nut are called a bolt, damm Americans have confused you as well, I am old enough to remember when this was very clear to everyone in the UK.

Mike

Mike,

Don’t want to hijack Gary’s thread.

I am certainly not confused by the Americans and the info is not based on my understanding but on British Standards + my 50 years as an engineer (30 of which running my own company) and my purchase of thousands of different size nuts & bolts. Not forgetting Screws

I have dug out my B Standards info and in the context of engineering a Bolt is described as a partial threaded fixing while a Screw is described as a fully threaded fixing. Clear definitions are given for Bolt thread lengths. Screws of any size can only have 2 x pitch length of un threaded section

For a long time now machine screws have been known in the trade as set screws.

We could always start another thread on fixings could be quite interesting what comes up .

 

[MikeJhn]

Interesting that machine screws and set screws don't have nuts on them, seems to back up my previous post, also interesting that you purchased nuts and bolts, not nuts and screws. #-o :lol:

I will take your 50 years as an engineer and I will raise you 5.

Oh and just for information I was the project leader on the writing of CP110 for BS and there are quite a few mistakes in it, so its not that plain sailing quoting BS's or relying on Wikipedia for information.

Mike

 

[woodpig]

I have several boxes of socket screws as they are my preferred fastener type for metalwork. Some of these screws have threads all the way to the head, some don't. I've seen all threaded hex head fasteners termed "set screws" and I'm ok with that but for some manufacturers it has to have a modified tip to be a set screw ie. dog point or cup point etc. Of course some set screws don't have a head either - socket set screw, which I'm sure some call grub screws. They used to have large printed charts in workshops years ago with drawings of all the different types of fasteners on them. Mainly for the benefit of apprentices I suspect but it would no doubt stop others arguing!

These guys seem to have it right.

http://www.anzor.com.au/stainless-steel ... ws/product