Nut & Bolt Sizes.

[Mark EisenParticipant @markeisen61287]

[Mark EisenParticipant @markeisen61287]

What are the most common Nut & Bolt sizes in both metric and imperial?

I have been trying to sort out my lifetime collection of Nut & Bolts, about 6 x 4 Lts container full, I keep finding these strange sizes, for me any way, like 9.5 mm, 6.75 mm, etc that will not match up with any of my thread gauges.

[Willliam PowellParticipant @willliampowell36769]

9.5 is just about 3/8 inch if that helps.

[Nick_GParticipant @nick_g]

.

Where do your interests fall.

General 'fixit' metric stuff if fairly straight forward. But go into :-
Motorbikes,
Cycles,
Old British cars,
Modern cars
Model making (British)
Model making (American)
Model making (European, metric but many fine pitches)
Clocks,
Old guns,
New guns,
The above just scratches the surface very, very thinly of the general ones. Then there lots of specialist ones.
……………………………………….. We could go on ………………… There are. Zzzzzzzzzzzzzzzzzzzzz

Sorry I know that is of little help to you is it.? But there really is no simple answer.

Nick

[Mike PooleParticipant @mikepoole82104]

9.5mm is about 3/8" so the tpi will decide if it is Whitworth, BSF, UNF, UNC,ME, brass thread. You will need a selection of thread gauges as whit and unified have 55deg and 60deg thread forms, metric is 60deg but pitch rather than tpi is the relevant measurement. There are many tpi, pitch and diameters that are defined in the standards so almost anything is possible. There are plenty of published charts of the preferred or common sizes but many apparently odd sizes fall within the standards. 6.75 sounds a bit odd but may be 7mm as threads alway measure under their nominal size due to crest rounding and truncation.

Mike

[Enough!Participant @enough]

Posted by Mark Eisen on 11/03/2017 23:31:56:

What are the most common Nut & Bolt sizes in both metric and imperial?

Depends which continent you live on.

[Ian S CParticipant @iansc]

And if you are looking for a specific nut and bolt from your collection, they won't be there, you will find plenty that are too big, too small, wrong head, wrong thread, so you use the bolt for turning down to make something else, and the next time you are looking for a bolt, wouldn't you know it, the one you turned down to make a pin is the exact one you need today. Then again you buy a new nut and bolt, get home and find that you have a dozen of them hidden away.

Ian S C

[Clive FosterParticipant @clivefoster55965]

Time to upgrade your sorting strategy.

Start by downloading a copy of the (nearly) all threads in order of size listing originally due to Andy Pugh and further refined by Ian Wright and Micheal Jones.

Text format here :- **LINK** in text format which may need bit of massaging for easy reading. Prettier version of the same data here with a link to an Excel file version **LINK** .

A PDF version arranged to print out on A4 here **LINK**.

Then roughly sort into suitable piles over a range of sizes. Maybe really tiny, up to 1/4 – 6mm, then up to 1/2 – 12 mm and a final pile for bigger ones. Pick over the piles and group out "looks the same" by eye. Now you are ready to start measuring. Set your thread gauges with a suitable selection of leaves pointing out and have at it. Odds are your looks the same sorting will have been good enough that one measurement covers a whole bunch of bolts.

Nuts you have to sort by size over flats then try a fit.

Should be all over by Christmas!

Clive.

[Russell EberhardtParticipant @russelleberhardt48058]

This page lists some of the more unusual thread standards: **LINK**

The engine of this car I restored used French Automobile Metric threads with Whitworth size hexagons!

Russell.

[richardandtracyParticipant @richardandtracy]

In my workshop I try to standardise on M6 & M10 for tooling.

As for what I produce in the workshop.. No standards possible. M12.4×2.4, triple start… That sort of silly thread is needed when trying not to take too much meat out of pen barrels & caps. M7.4×0.55 is a thread moulded in by one of the nib manufacturers into a nib housing. Simply absurd, but have to live with it.

Regards

Richard.

[Mark EisenParticipant @markeisen61287]

Thanks for your replies,

At the moment my interests are General 'fixit' with a preference to metric, when I get a bit more practice I want to start making model engines etc.

Ian that is a perfect description, If I need 4 bolts, I will only find 2 nuts and the washers will be either too big or to large.

Very nicely restored car Russell.

[John FlackParticipant @johnflack59079]

Checking on a link, we seemed to be overwhelmed for choice. Generally the choice is made for us by those who make whatever eqpt we use. When a bespoke is desired is there a specific criteria to be observed?. I simply look at what is to hand and think "that seems about right" and proceed from there. Assuming(?) fasteners are made to equal tolerances would a fine thread be preferable or non preferred to a coarse thread for general fastening use? If so why?

Chart sizes indicate that 20BA nuts are possible. Has any living soul ever seen a nut of this size, and where can I get some?

[Neil WyattModerator @neilwyatt]

Posted by John Flack on 13/03/2017 10:27:48:

Has any living soul ever seen a nut of this size, and where can I get some?

Not without a hand lens…

Neil

[SillyOldDufferModerator @sillyoldduffer]

I got so fed up searching my random collection of nuts and bolts that I 'standardised' on metric and bought a stock of the sizes I use most. It's wonderful: now when I need a nut and bolt I just reach for the right ones. Mostly!

Back in the real world, it's amazing what you have to cope with if you like repairing stuff. Cars I owned in the last century had odd mixes of Metric, UNF, UNC, BA, and some I never identified. It was and is a complete pain in the botty.

Strangely I've only come across Whitworth threads once. Dozens of nuts and bolts (about 3/4" ?) were left lying about after a railway line was dismantled near my school. No details unless Neil insists on a MEW Article but you can make a very satisfying bang with two ex-British Railways bolts, a nut and a certain domestic product.

Dave

[Harry WilkesParticipant @harrywilkes58467]

Posted by John Flack on 13/03/2017 10:27:48:

Checking on a link, we seemed to be overwhelmed for choice. Generally the choice is made for us by those who make whatever eqpt we use. When a bespoke is desired is there a specific criteria to be observed?. I simply look at what is to hand and think "that seems about right" and proceed from there. Assuming(?) fasteners are made to equal tolerances would a fine thread be preferable or non preferred to a coarse thread for general fastening use? If so why?

Chart sizes indicate that 20BA nuts are possible. Has any living soul ever seen a nut of this size, and where can I get some?

John many years ago I was taught that fine treads are stronger than it's course version it was suggested up to 60% stronger but at the same time I was told a fine thread is more prone to seizing. Until metrification BSF & BSW were the more common fasteners on the shop floor with BA used on electrical parts.

H

[Gordon WParticipant @gordonw]

My system, for what it is worth, Is just to put all the bits in the same bucket. For eg, dismantle a computer/ printer, all the bits including nuts and bolts go in a box or bucket. Tractor bits go in another, etc. etc. This may seem a bit rough, and it is, but seems to work well in practice.

[BazyleParticipant @bazyle]

Nice link by Clive to lots of threads but doesn't include Model Engineer threads and more surprisingly UNEF (which you might need to know for a camping Gaz cylinder I think)

[John FlackParticipant @johnflack59079]

SOD

Used to do that at school with 1/4 inch items and "caps" my first intro to engineering!!!!!!!

Harry W

That perhaps explains why Mr Prestwich of N 17 used 26 tpi on his products, but why with a reduced hex sized nut??

[Anonymous]

Most of my older books have charts where BA sizes go down to 23, with an OD of around 0.3mm. I expect that the smaller sizes are no longer available, but may well have been used in the past for small instruments and watches.

Andrew

[John FlackParticipant @johnflack59079]

I don't wish to annoy any body on this forum or to be annoyed by its members (I have the medical profession making a very good job of that) my contribution was to ask"what criteria determines the choice between a coarse or fine thread" informing me that you have standardised on M 8 or M 10 leaves me to ask is that fine or coarse thread. If the response is "Coarse of course"? That still leaves open my question WHY? This was a serious ask as many tyros will be using using historical designs where some understanding of retention strength may be critical when seeking alternative fasteners to that specified

I shall now return to usual state of Eunoia

[SillyOldDufferModerator @sillyoldduffer]

Posted by John Flack on 13/03/2017 14:19:55:

"what criteria determines the choice between a coarse or fine thread"

…

I shall now return to usual state of Eunoia

First of all many thanks for 'Eunoia', which is a new one for me.

Let's see if I remember what I read correctly. The gist was:

• In similar materials, fine threads are stronger than coarse ones.
• A coarse thread will be stronger than a fine thread only when one material is softer than the other. (e.g. a steel stud in a cast-iron block.)
• Coarse threaded fasteners are quicker to assemble and disassemble, which is a cost advantage in manufacturing.
• A fine thread is harder to vibrate loose than a coarse one.

Dave

[richardandtracyParticipant @richardandtracy]

A coarse thread is more likely to fit on another coarse thread if both have not been as well made as they could have been. So being a coarse thread makes stuff fit together better & quicker.

Coarse threads have bigger clearances, so use less metal, so the manufacturer pays for less metal & it's fractionally cheaper for the manufacturer. Not important unless making millions of fasteners.

The British & International standards state that the thread pitch may be omitted from the definition if coarse is used, else the pitch should be specified. People are basically lazy, so don't want to write it down if they can help it.

Regards,

Richard.

[Russell EberhardtParticipant @russelleberhardt48058]

Posted by Andrew Johnston on 13/03/2017 12:07:01:

Most of my older books have charts where BA sizes go down to 23, with an OD of around 0.3mm. I expect that the smaller sizes are no longer available, but may well have been used in the past for small instruments and watches.

The chart I linked to goes right down to 25 BA (0.25 mm OD) but I've never seen anything that small. Watch screws are now metric and Cousins list taps and dies down to 0.3 mm. I don't fancy using them though. 12 BA is the smallest I've cut.

Russell

(edited for miss-typing)

Edited By Russell Eberhardt on 13/03/2017 15:00:34

[Richard S2Participant @richards2]

I don't know what would be 'Common Sizes' in bolts/nuts across the various thread forms.

I tend to use everything except Metric in my interests of playing with old British or American machinery.

My Models are ME, Whitworth or BA forms, the latter only down to 16BA. I do have a cheap set of Metric Taps n Dies from 30 years ago, but never used them.

S'pose it is a matter of time before I have to use Metric on something for the Warco WM16 !.

[Mike PooleParticipant @mikepoole82104]

The thread pitch selected for a particular application is determined by the material and the task being performed by the fastener. Soft materials and cast iron often require a coarse thread whereas applications like big end bolts will use a fine pitch thread. If you consider a thread as a wedge wrapped in a circle it will make sense that a finer pitch will be able to exert more force on the bolt. You will always have to compromise as the finer threads are smaller but the coarse threads are deeper, so too fine and the thread will have low strength and too coarse will reduce the core size of the bolt. Fine threads are less inclined to loosen but if it is important that a nut does not come loose there are plenty of options from shake proof washers to various types of locking nuts. Bolts can have inserts or thread locking liquids applied.

Mike

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