Formula for Nut Sizes and Wrench Sizes?

See http://cr4.globalspec.com/thread/42836/Which-Wrench-to-Use-A-Cheater-s-Guide

GA

handy link from that thread:

Confirms Blink's post below

I am not comfortable with imperials .

But spanner no 22 seems to be 22mm which will almost suit a 1/2" nut @20.83

A link is here

Hi Guest,

I think you may have gotten confused somewhere along the line.

The nearest metric size to fit ½" is 13 mm.

Are are you referring to the shaft of the bolt as ½" so the 'head' of the bolt will be 22 mm?

Good luck.

Unless it is an extra heavy nut, the standard size of nut for 1/2-inch bolts is 3/4 inch ≈ 19 mm. Not that one should mix these systems in the first place, but sometimes ya gotta do what ya gotta do....

There is a range of bolt sizes in which the nut size is 1.5 x bolt diameter, but this is not consistent in small and large sizes, so one must consult literature rather than attempt to calculate.

Hi Tornado,

How you doing?

I think I might have read the question wrongly.

I am guessing when I say the UK metric size for 13 mm/ ½" nut is ~ ¼".

I read the nut size and did not think of the actual bolt shaft size much.

I just saw 22, which I assumed was 22 mm, and the Metric (½") is 13 mm, not 22 mm.

Sorry not well written.

Take care and good luck.

This whole issue is complicated by large-head nuts, nonstandard sizes, differences between US/metric, and not even God knows what else.

That said, there is virtually no relation between wrench size and bolt diameter, except in the range of standard sizes from 3/8" to 1" bolts or so (where nut size = 1.5 x bolt size). Even there, the variations almost outnumber the usual combinations.

That's why my original somewhat facetious post said wrench = nut + ~.005 (enough clearance to avoid interference). In the field, if someone stole the 3/4" socket, you make do with 19 mm (if they didn't steal that as well). And vice versa. Nuts and wrenches are relatively forgiving; don't try this with taps and dies. For metric bolts, use a metric Crescent wrench (250 mm vs 10") ?!?!?

Hi Tornado,

Hope you had a nice holiday so far?

I am alone, but at least there is no one to argue with?

Yes I know what you mean. It is an interesting question but especially on larger sizes I just make sure I have the correct one or two wrenches!

I remember when I was in my teens, the be all and end all was the 'socket set' with the largest amount of sockets! Probably the most sockets I ever used was 6 to 8 in number, not size. yet I still had another 25 to use when and IF I ever bought something the the half dozen I used did not fit................. Have you ever found a ¼" nut that cannot be undone with an adjustable? Perhaps the smallest I have found that I came across more than once is ⅜", and that was on a tiny tape recorder.

In truth no one really needs more than perhaps a dozen sizes. I do not have the space and have not worked on engines and such for about ten years so I make do with adjustable wrenches now. Three covers all the jobs I am ever likely to do!

I find with working on computer and the like, and I was going to say what I found most useful, and what is mostly used on such machines, ......... but I have forgotten! They look more like a screwdriver than a wrench. Sorry my brain failed me when I needed it most!.................... But, hey what new! It always does.

Take care and enjoy the rest of the holidays!

I think you are thinking of a nut driver. They certainly are very handy. A jeweler's screwdriver is great for that small stuff too.

Hi Lehman57,

Thanks for the reply post! And I hope your holidays are going as OK?

I remember the name now. It is Torx? I think that is what the screwdriver like small nut and screw tighteners are called. Torx Bit Drivers.

Is that what you lean? If not can you please send a link, if you do not mind?

Take care

Hi bb - hope all's well with you.

FYI, 'torx' is name of a specific security-type screw head.

Here's the head (countersunk version):

& here's the driver:

The hole in the head is to accomodate the 'pip' which some versions have:

Cheers,
John

Hi JohnDG,

Nice to hear from you John.

I was and am thinking about Torx, (I remembered tonight!) because I am into knives and a lot of them are constructed with Torx. I rightly or not, also had the impression computer backs were also bolted on with the same system. Forgive me if I was wrong. BTW, great illustrations!

I tend to know what I am looking for but do not know what they are called, that is the Torx system drivers. Very small fasteners.

Take care and I wish you the best of luck.

Torx? No, not what I was thinking. JohnDG's photos are a good illustration of a Torx driver & fastener. As far as I know they are not used on the little fasteners like inside a computer.

What I was thinking, a nut driver, is like a small 6-point socket on a screwdriver-like handle; it does hex nuts or screws. I have seen them up to 1/2". These are similar to using a standard socket on the end of a socket extension.

Thus:-

(best snaps I could nab at short notice).

The best nut drivers have a hollow shaft that can accommodate the screw projecting beyond the nut. That way, you can tighten the nut all the way down.

Agreed! So bloody frustrating when the nut stops (or will not start) engaging with the tool because the screw/stud/whatever is too long for the tool.

Another big frustration is a nut spinner with in unnecessarily large OD, when the nut is close to any other projection (side panel, neighbouring nut etc.). I used to have one (5.5mm A/F to suit M3 nuts) which was ground down to get to all but the tightest of corners. Someone nicked it .

Hi Tornado,

on the whole I do agree with you. but there is items like small folding knives which do not have room to use ¼" fasteners, and of course raised fasteners are a no no of a knife for the most part anyway. The Torx on a folding knife do not need to deal in a great deal of pressures, really just need to hold the various tools and other implement aligned, rather that tightly together.

Hey, all the bast kind of wishes to you..............

Take care and good luck

I prefer socket head screws to Torx. They allow you to use a ball end driver that allows you to access a screw from an angle, very important some times. And yes they make Flat head socket screws that would work nicely in a pocket knife assembly. I have used them with threads as small as 0-80.

Hi Maxxx,

The screws I will be using the Torx things on will be on a bench so no problems with getting at them. Though ususally I would think the same way!

A whole lot of knives (folding) use Torx and that is what I am referring too.

Take care.

There are many benefits to Torx not the least of which is a secure engagement between the tool and fastener. If I designed things that were not such complex assemblies with intense manufacturing demands I would use Torx where I could. As it is, assembly line and or cell versatility makes socket heads across the board my best friend. If I do my design carefully I can allow manufacturing to set up only a few hanging pneumatics with as few sizes as possible and they can assemble any of multiple sub assemblies with the same tools. OK we may be off topic from wrench size -vs- nut size but in reality the entire subject seems to have been off topic from the beginning.

Hi Lehman,

Yes you are right. I think I may have been mistaken about Torx on desktop computers, but they are on some laptops.

Take care and I wish you well!

"This whole issue is complicated by large-head nuts, nonstandard sizes, differences between US/metric, and not even God knows what else."

Non-standard sizes! Just this afternoon I was using a 19/32" wrench on a nut for a 5/16" stud. 5/8" was too loose & 9/16" wouldn't fit! And it was not metric since it was made in 1925--but I must confess that I have replaced those nuts.

" a nut with size 1/2" has a wrench No. 22"

My nuts with size 1/2" has a wrench 1/2"

There's your problem. Get a set of wrenches with the dimension of the nut on them and throw those wrenches with whole numbers in the trash.

a 1/2" nut does not use a 1/2" wrench.

"a set of wrenches with the dimension of the nut on them"

Nut size is ambiguous. In the US, a 1/2 inch wrench fits a 1/2 inch nut -- you'll never convince mechanics otherwise.

With respect to wrenches, the nut size is the dimension across flats. However, a 1/2 inch nut (measured this way) actually fits a 5/16 bolt or stud (which is measured on the diameter).

Making it even more inconsistent is the fact that nut sizes (across flats) are not consistent with respect to the bolt size, with fine thread nuts sometimes having a different dimension across flats from coarse thread, in the larger sizes.

The metric nuts are better but also inconsistent. If you work on European cars, you use a 13mm wrench very frequently. If you work on Japanese cars you never use one, but instead use 12 mm wrench for 8mm bolts.

Then there are the two curses inflicted on the world by the British Empire: BS and Whitworth.

Good! American and Metric have the wrenches labeled with the size across flats of the nuts. However the BS and Whitworth are labeled with the stud/bolt size I believe--not the nut XF size.

Then consider that regular hex and heavy hex nuts for the same bolt size take different wrench sizes because the XF size is larger for the heavy hex.

???????

How could someone score me as "off topic" with my ???? when it's a direct reference to a Guest's comment that one does not use a 1/2" wrench on a 1/2" nut? What reply could possibly be more "on topic"?

Hi Maxxx,

Just a guess here, but it may have been because someone has seen "???????" and thought you said nothing? I know what you meant but, it does not follow all did?

Take care

If you mark (or vote) yourself off topic, it automatically tots up 5 votes. Also, if you reply to an off-topic comment, it inherits the "off-topicness" unless you uncheck the off topic checkbox before posting.

They're not out to get us, honest.

[As an example, I've just unchecked the off topic box on this post].

I appreciate the education. Allow me to compliment you JohnDG... and babybear, and Tornado, and a few, very few, others who really rock with good information presented clearly. Not just on this thread but on also on others I have seen you guys prominently. Even when, on occasion, the question, primary or secondary, should not have needed to be asked or maybe is asked in the wrong way. Case in point... this thread... nut size -vs- wrench size. You guys gave reasonable and helpful answers when my first response to the question was that it was a joke. 1/2" nut = 1/2" wrench, 19mm nut = 19mm wrench. But you guys, quite reasonably, get into many issues that I would not have thought to discuss. I'm still not sure what the original question should have been. Is he actually looking in fact for a correlation between (Thread size) and nut/wrench size? This I would have taken seriously. I will learn this lesson form these few of you... that I should try to be more introspective when reading these requests for help and maybe try to figure out what the questioner really needs to know. This really is an educational forum. You really are good guys. (Assuming "guys" is the appropriate term here babybear)

Welcome!

I'm still not sure what the original question should have been.

The answer, I suppose, is "who the heck knows?" Often, the original poster will come back to clarify the question, but not infrequently, he never returns.

My guess is that the poster is from a country in which "inch size" wrenches are uncommon, but has had occasion to work on equipment that has "inch size" bolts. Although the nut on a 1/2" bolt is usually 3/4" (which is close enough that a 19mm wrench usually fits) perhaps he found a 1/2" thread size bolt or fitting to which a 22mm wrench could be successfully applied (spark plug? 12 point socket on square-headed bolt?). A 13/16" spark plug wrench is close enough to 22 mm that a 22mm wrench could be used to remove a spark plug, I suppose. (He may be also be generalizing from British Standard or Whitworth, which would surely throw a spanner into the works of coming up with any sort of formula.)

But unless he returns, we will never know what he had in mind.

(Incidentally, I share your like of ball-headed hex keys, although I cringe a little when using them, because when they are tilted, the engagement goes from 6 lines to two points.)

My take on the OP's question was:

"is there a rule like: 'B size bolt needs a B x 1.5 AF spanner, except after 12.4mm add 2mm' (etc)"

As we (all) know, no such relationships exists.

Thank you guys for showing me the sense of community here. When I first came across CR4 I thought it was a cute time killer for times when the work load was light. This small group, you know who you are, has changed that perception for me. This is a real resource for serious answers as well as tension relief through a little peppering of humor. Love it!

Hi Maxxx,

You have encapsulated what the site is in your few words! Do not forget there is other part of the site science etc and parts you can search for publish info as well!

Take care

Hi Maxx,

I really appreciate your note and really all I do is try and give an accurate answer. When the question is not clear and or the questioner does not return, which I think is the case on this thread although I for one have learned a lot of stuff about wrench and bolt sizes etc, we will never know what the OP, (Original Poster) meant!

I try to give the thread a helping hand by reading between the lines. Often I realise the OP does not have English as a first language so you have to 'interpret' somewhat?

Take care and good luck with the rest of your time on CR4!

Hello Lehman57,

Thanks for the reply post!

Well here's another off topic which I have listed as 'on topic' to allow others to see and perhaps find their own pictures of odd-ball-item to ask questions about!

I thought I should put what the meaning of "OP" was as I was replying to a relatively new member and they may not realise?

Do you have any other "can you guess what this is" questions, lined up? I really like those.

In the 'old days' the skilled artisans needed these 'instruments' to do what is now done in a factory and the item is delivered complete and ready to fit or ready working? My Father has a whole lot of stuff but most unfortunately went rusty when the cellar flooded.

Take care and all the best kind of luck for the coming year!

Hi JohnDG,

I was wondering where the off topic votes came from when we sent a post as 'off topic'. Now I know, thanks!

Take care

I don't believe there is any "formula", but there are published standards.

Here's a handy chart:
http://www.imperialinc.com/pdf/A_CapScrewHeadWrenchSizeChart.pdf

Wrench size = across-flats nut size + ~0.005 in.

Please translate your motto. all I can get is wine,truth,throat,song,and water.?

Not edumacated in Latin.

thanx.

Somewhere I think we are about to miss the [bolt] boat..Being in the wrench grabbing field from my very early years and head set against the metric system, I'm now 74 and have to realize I do have to use the knowledge I've gathered under the hood, tho against my head set judgements. The metric system is here to stay..so lets use the antiquated knowledge we have and adapt..Neat 'huh'..A half inch bolt does not use a half inch nut, the wrench to fit a 1/2 inch nut is 1/2 american standard. Truly you will find a Metric wrench that will closely fit, 13mm..'closely' meaning you will round off the nut on multiple use. Bolts are not nuts, wrenches are made to tighten nuts to bolts regardless of the size of the bolt..A metric nut will need a metric wrench.

Hi Farzad,

What wrench to use on the size of bolt - Page 2 - OnlineConversion ...9 posts - 2 authors - Last post: 21 Oct 2008If useing extra heavy nuts add 1/8th to your wrench size. ... slot) the formula is Width Across Corners = Width Across Flats/cos(30deg) ...

forum.onlineconversion.com/showthread.php?p=55319 - Cached

Spanner Jaw SizesThis page has a useful chart for comparing spanner sizes (a wrench in the USA) and common nut/bolt use. Although it is believed to be correct, ...

www.sat.dundee.ac.uk/~psc/spanner_jaw.html - Cached

Is this what you mean?

Good luck

Hi farzad,

Thanks for this thread.

With what? That isn't even a reasonable request.

Adjustable spanner - Wikipedia

According to reports, then, a <...22...> millimeter-across-flats spanner fits a <...1/2"...> Whitworth nut even without the use of inappropriate apostrophes.

It's no big deal, is it?