1/2 inch vs 13mm

[Nigelhirst]

Hello everyone. Just a quick thought.
I have two SK sets - a 1/4 drive metric normal and deep and a stubby wrench set.
The socket set stops at 12mm and the wrench set at 18. Here in Europe 13 and 19mm are common sizes, so I asked the supplier why they are 'missing'. The answer was 'because in the US you would have 1/2 and 3/4 already and use those.'
Well, 13mm equates to 0.512 inch so a 1/2" would be tight, but 19mm is a better equivalent at 0.748".
I wonder if manufacturers actually bother to use different broachings though
Nigel

 

[turtleman321]

There is definitely a difference between a 13mm and a 1/2" wrench/socket.

I have started to round fasteners with a 13mm because I was too lazy to grab the proper 1/2" wrench.

Even in my craftsman sets there is a visual difference between the two.




On the other hand a 19mm and 3/4" interchange very well even if the wrench is actually incorrect for the fastener.

 

[Mr_B]

Good 1/2" wrench won't fit a good 13mm hex bolt or if does it tight, sometimes useful on a rusty metric bolt but not often a good cross size .
Companies miss it in their kits when want cheapest set option . Lot of low cost wrenches have such poor sizing it lucky to fit size it stamped at well enough :-/

 

[rhandwor]

A well worn impact 1/2 inch will fit a 13mm bolt. I have a 13mm male pipe plug Koken and a 1/2 Matco male pipe plug socket. I checked a Wright 1/2 inch 10 point and it fits the Matco but not the Koken. I have a 1/2 drive Wizard 8 point that will fit the Koken. I save it for a 13mm pipe plug if I ever run across one.

 

[Dave455]

Every set has to stop somewhere, and you have to remember that British/ISO metric use a different range of sizes from German/DIN Metric, Japanese/JIS Metric and American ANSI Metric! The set maker has absolutely no idea which standard you are using so stops when convenient!

I doubt that your dealer has much insight into the thinking of S.K. though. In my experience most American cars now use metric anyway, and a lot of folks are more likely to have metric tools than SAE. Most U.S. mechanics that I've met, amateur or pro, know more about it than to use an inch size socket on a metric fastener too! That's probably an insight into your dealers thinking!

 

[Nigelhirst]

Every set has to stop somewhere, and you have to remember that British/ISO metric use a different range of sizes from German/DIN Metric, Japanese/JIS Metric and American ANSI Metric! The set maker has absolutely no idea which standard you are using so stops when convenient!

I doubt that your dealer has much insight into the thinking of S.K. though. In my experience most American cars now use metric anyway, and a lot of folks are more likely to have metric tools than SAE. Most U.S. mechanics that I've met, amateur or pro, know more about it than to use an inch size socket on a metric fastener too! That's probably an insight into your dealers thinking!

Yes, well 'right tool for the job' I say. I should probably have called this thread 19 mm vs 3/4 because the difference is much smaller

 

[Cope]

Snap-on makes 1/4" up to 15mm.

 

[nbpt100]

If you have one of those splined "Universal" sockets or wrenches the 1/2" and 13 mm are more compatible. Otherwise they are not. As some said about you can get away with it in some instances. It is far from a reliable substitution.
I don't buy the explanation from your supplier.
Most 1/4" drive sets I have seen go up to 13mm and 1/2". I have on occasion seen some go up to 14mm and 9/16".

You can safely interchange a 19mm for a 3/4" or a 8mm for a 5/16". In both cases the difference is about .002".

For those who are curious there is a thread on here about which hex bolt sizes are interchangeable between metric and SAE.

 

[Yankee]

The Craftsman 1/4 drive set I got 20 years ago only went up to 12mm. (Later on I purchase the 13mm single)

My guess would be in most situations you would be using a 3/8 drive for a bolt that size, so only have that size available as a single... keeps the set price lower.

 

[Mr_B]

I don't buy 1/4 set sockets unless goes up to 14mm minimum, wouldn't choose spanner set stopping at 18mm, normal is 8 to 19mm and 16 18mm sizes likely skipped . 19 and 3/4 good cross match though .

 

[Gmonkee]

The basis of a good minimalist kit is to get a full metric set and add the three sizes in SAE not covered in metric.

Go with DBE or DOE and a dozen wrenches total get you up in range.
Of course this flies into the face
of OCD and confuses some but it works well.

I need a small expendable kit with full range to 22mm, DOE with a 3/8" socket set set up the same way get me there.
While many marvel at the red tin condos with tens of thousands of dollars of depreciation inside, my kit is all profit since a month after new. It isn't cool but the paychecks are.

 

[ihateminimumwage]

Hello everyone. Just a quick thought.
I have two SK sets - a 1/4 drive metric normal and deep and a stubby wrench set.
The socket set stops at 12mm and the wrench set at 18. Here in Europe 13 and 19mm are common sizes, so I asked the supplier why they are 'missing'. The answer was 'because in the US you would have 1/2 and 3/4 already and use those.'
Well, 13mm equates to 0.512 inch so a 1/2" would be tight, but 19mm is a better equivalent at 0.748".
I wonder if manufacturers actually bother to use different broachings though
Nigel

Is the wrench set the SK86247? They offer the smaller 7pc set that goes up to 18mm (and is missing 11mm & 16mm) and the full SK86240 10mm-19mm set with no skipped sizes. The smaller set is made to cover sizes that don't cross over to SAE, as 11mm - 7/16", 16mm - 5/8", 19mm - 3/4".

That sounds like an oddball socket set (SK89009 maybe?). Most of their sets go up to 15mm, with only a couple of the smaller sets stopping at 12mm. I'll admit, that's an odd size to stop on vs 13mm.

Snap-on makes 1/4" up to 15mm.

So does SK.

 

[johninct]

I have worked on things that I know are SAE or metric and put the correct wrench on the bolt only to find a sloppy fit so I sometimes interchange SAE and Metric to get a tight fit. Manufacturing tolerances ,corrosion and maybe wear play a part. I want a tighter fit if possible.

 

[rlitman]

There is definitely a difference between a 13mm and a 1/2" wrench/socket...
On the other hand a 19mm and 3/4" interchange very well even if the wrench is actually incorrect for the fastener.

Yes, there is a huge difference between 1/2" and 13mm. Enough that 1/2" should not fit on 13mm parts, and 13mm will round 1/2" parts. I find this to be a big issue on battery terminal bolts, where idiots round over 1/2" nuts all the time with their 13mm wrench that they think fits all battery terminals.

I happen to own Snap On 19mm and 3/4" wrenches. They're completely interchangeable, and I suspect they use the same broach on both. However, it happens to be a size I don't mind owning duplicate wrenches in.

 

[PJNJ]

I looked at SK's catalog and it seems that you may have their No. 89009 set that only goes up to 12mm in shallow and deep. The No. 1314 only has shallow sockets and goes up to 13mm. All of the rest of their 1/4 sets go up to 15mm in six point (shallow and deep) and one goes up to 15mm deep and 16mm in shallow. And they have two semi deeps sets that go up to 15mm - 41692 with just sockets on a rail and 91824 that includes a ratchet and spinner handle.

SK offers different set sizes to probably satisfy need and price point. Your supplier is absolutely wrong and you should ask if he offers the other SK sets such as:
1313 (only shallow metric up to 15mm)
1312 (deep up to 15mm)
91848 (up to 15mm shallow and deep plus SAE and ratchet, etc.)
91844 (up to 15mm shallow and deep plus SAE and ratchet, etc.)
91860 (that goes up to 16mm in shallow, 15mm deep plus SAE and ratchet, etc.).

 

[kblee27]

Yes, there is a huge difference between 1/2" and 13mm. Enough that 1/2" should not fit on 13mm parts, and 13mm will round 1/2" parts. I find this to be a big issue on battery terminal bolts, where idiots round over 1/2" nuts all the time with their 13mm wrench that they think fits all battery terminals.

I happen to own Snap On 19mm and 3/4" wrenches. They're completely interchangeable, and I suspect they use the same broach on both. However, it happens to be a size I don't mind owning duplicate wrenches in.

I turned battery terminal nuts all the time.
Sometimes a 12mm wrench fit, sometimes a 13mm wrench fit.
I never know if somewhere in between, a 1/2" might fit, due to a SAE terminal.

At one time, I tried to use 1/2" (12.7mm) wrench since most of the cars here are on metric. But one time, it didn't a 13mm bolt, that was tighter in spec. So I stop using that 1/2" wrench.

 

[6PTsocket]

Yes, there is a huge difference between 1/2" and 13mm. Enough that 1/2" should not fit on 13mm parts, and 13mm will round 1/2" parts. I find this to be a big issue on battery terminal bolts, where idiots round over 1/2" nuts all the time with their 13mm wrench that they think fits all battery terminals.

I happen to own Snap On 19mm and 3/4" wrenches. They're completely interchangeable, and I suspect they use the same broach on both. However, it happens to be a size I don't mind owning duplicate wrenches in.

The difference between 13mm and 3/4" is out at the third decimal place. I doubt that forging techniques are to that tight a tolerance. I have used 13mm for 1/2" on occasion without any damage but if I ran up sgainst a lot of resistance I would not push it. 13mm is not that sloppy. I have found that a 1/2" socket will sometimes fit on a 13mm fastener, though a bit snuggly.

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[rlitman]

I turned battery terminal nuts all the time.
Sometimes a 12mm wrench fit, sometimes a 13mm wrench fit.
I never know if somewhere in between, a 1/2" might fit, due to a SAE terminal.

At one time, I tried to use 1/2" (12.7mm) wrench since most of the cars here are on metric. But one time, it didn't a 13mm bolt, that was tighter in spec. So I stop using that 1/2" wrench.

Battery terminal pliers are the answer to your problem:

 

[padroo]

I have used metric sockets on sae bolts because of rust. I was removing a water pump on my flat head Ford once and one of the bolts is inside the water hose opening constantly exposed to the rust and corrosion of the cooling system. My dad said they usually broke the water pump with a hammer to remove the bolt, my thought was how crude. I found whatever mm socket that was just smaller than a 9/16 bolt head and drove it on the bolt head and removed it.

 

[four.cycle]

The answer was 'because in the US you would have 1/2 and 3/4 already and use those.'

"Your supplier is absolutely wrong..."

^ Correct.

The Craftsman 1/4 drive set I got 20 years ago only went up to 12mm.

^ Earlier US-made metric sets of both sockets and wrenches skipped sizes or only contained a limited range of sizes (as in Yankee's example of his older CM set only going up to 12mm.)
Newer sets (from most of the better-known US manufacturers) contain every size, or have a broader range (i.e., 14mm and 15mm being included in 1/4" drive sets.)

I'm not going to speculate on the "why" part of it. Just reporting my observations from looking at thousands and thousands of wrench and socket sets on Ebay.

 

[anndel]

I would get the 13mm and 19mm as individuals to fill the missing common sizes. Using 1/2 and 3/4 will round your nuts/bolts to a point where you'll have to use a locking plier to remove it.

 

[derosa]

With the couple cribs I built I found I could not get by with 13mm, just snugging things would round the head of a bolt, all the hardware was US and clearly not metric and 13mm did not interchange. Maybe my wrench is a little loosed or the bolts more precise but I wouldn't want to tighten a critical piece or loosen a stuck one with 13mm. 3/4-19mm seems fine.

 

[BDT/NWMN]

Sk tools are top quality, but I do want the proper Size.. If they skip a size in a set, I simply skip the SK set, and buy a complete set of a different brand.

 

[PJNJ]

Sk tools are top quality, but I do want the proper Size.. If they skip a size in a set, I simply skip the SK set, and buy a complete set of a different brand.

And what sizes do they skip in the 1/4 socket set and stubby wrench sets?

In addition to the above socket sets I cited that have no skips, the stubby wrench sets go from 10 to 19mm with no skips (No. 86240) and 20 to 24mm with no skips (No. 86241).

 

[T45]

The socket set stops at 12mm and the wrench set at 18. Here in Europe 13 and 19mm are common sizes, so I asked the supplier why they are 'missing'. The answer was 'because in the US you would have 1/2 and 3/4 already and use those.'

this is BS, the only overlaps are really more like 8mm, 11mm and 16mm, which sometimes you do see redacted sets skip (even in europe).

Supplier is pulling your leg, nobody uses 1/2 for 13mm regulalry unless the hardware is stripped or the broach(es) are extremely poor--ie, the 13mm is so sloppy the 1/2 actually fits correctly. Don't laugh tho, some wrenches are this bad..with 0.25mm overages etc.

 

[Gmonkee]

American sets tend to have no missed sizes. A European kit might not have 12, 14 or 18 and an Asain set 11, 13, 15. It is because the cars built to those standards don't use all the sizes.

My L wrench set was clearly a Asain market set, I had to make the missing sizes myself. The Wurth sets are clearly aimed at the European market and cars.

 

[Sticks McGee]

Snap-on makes 1/4" up to 15mm.

 

[6PTsocket]

I would get the 13mm and 19mm as individuals to fill the missing common sizes. Using 1/2 and 3/4 will round your nuts/bolts to a point where you'll have to use a locking plier to remove it.

3/4" is 19.05mm. That is 0.0019" oversize Do you really think you can tell the difference or sockets are sized that closely?

^ Correct.



^ Earlier US-made metric sets of both sockets and wrenches skipped sizes or only contained a limited range of sizes (as in Yankee's example of his older CM set only going up to 12mm.)
Newer sets (from most of the better-known US manufacturers) contain every size, or have a broader range (i.e., 14mm and 15mm being included in 1/4" drive sets.)

I'm not going to speculate on the "why" part of it. Just reporting my observations from looking at thousands and thousands of wrench and socket sets on Ebay.

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[KnurledNut]

Snap-on makes 1/4" up to 15mm.

You sure?

https://store.snapon.com/Shallow-mm-chrome-Socket-Metric-Shallow-16-mm-6-Point-P631096.aspx

 

[M6erfan]

yeah, pretty sure SK has 16mm 1/4" sockets also

 

[shockwave]

Usually with my experience 1/2 comes in with a rounded off 13mm fastener and usually a 6 point

7/16 and 11mm can interchange
7/8 and 22mm can interchang
3/4 and 19mm can interchange
5/16 and 8mm can interchange
1 1/16 and 27mm can interchange
5/8 and 16mm can interchange
These are not exact but can be used with sae

Now 1/2 and 13mm are close but not same like
1/4 and 7mm really like 7.6mm
9/16 and 14mm really like 14.5mm
3/8 and 10mm are close but 10mm is bigger slightly
11/16 and 17mm are really 17.5

A lot can be used but with you being in Europe 13,14,15,16,17,18,19,21,22,24 will be very common

And lastly 1/4 should go to atleast 14mm rarely do I use my 15 in 1/4 drive look at gedore,hazet stahlwille of facom might be better options than sk in Europe

 

[BDT/NWMN]

And what sizes do they skip in the 1/4 socket set and stubby wrench sets?

In addition to the above socket sets I cited that have no skips, the stubby wrench sets go from 10 to 19mm with no skips (No. 86240) and 20 to 24mm with no skips (No. 86241).

5.5MM socket is skipped in some of their 1/4" drive sets; but not every set..

I use that size often, so it is the first socket I check for in a set..
My SnapOn, ProTo, and Craftsman sets all came with a 5.5MM.

 

[nbpt100]

I have worked on things that I know are SAE or metric and put the correct wrench on the bolt only to find a sloppy fit so I sometimes interchange SAE and Metric to get a tight fit. Manufacturing tolerances ,corrosion and maybe wear play a part. I want a tighter fit if possible.

I do the same all the time. Even trying 12 pt. vs. 6 pt to get the tightest fit.

3/4" is 19.05mm. That is 0.0019" oversize Do you really think you can tell the difference or sockets are sized that closely?

Thank you! The real number to look at at a guide is the % difference between the nominal sizes. For example it is pretty well accepted that an 8mm and 5/16 are interchangeable and the nominal difference is .0025". The % difference is .8%. You have nearly the same difference of .0020" between a 19mm to 3/4. While the % difference is less than half at .3%. If you believe 8mm and 5/16 are interchangeable you should be even more comfortable interchanging a 19mm and 3/4. The point here is, as you go to larger sizes you can get away with a larger nominal difference and be safe to not round any thing in normal condition. A good example of this is a 1 1/4" is interchangeable with a 32mm. The difference is about .010" and the % difference is .8%. This is the same as the 8mm to 5/16".
Of course there are are always exceptions! When you deal with rust, low quality tools and worn out items. It becomes a judgement call.

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5.5MM socket is skipped in some of their 1/4" drive sets; but not every set..

I use that size often, so it is the first socket I check for in a set..
My SnapOn, ProTo, and Craftsman sets all came with a 5.5MM.

Good point. My 30 yr old craftsman set skipped this but I see the newer sets include it. Often a 7/32 can substitute.

 

[6PTsocket]

The difference between 19mm and 3/4" is not 3%, as somebody said. It is less than 0.3% or 0.26 % to be a bit more exact. I stand by my original statement. There is no functional difference between the two sizes. We are talking about 2 thousandths of an inch for a 3/4" socket.


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[PJNJ]

5.5MM socket is skipped in some of their 1/4" drive sets; but not every set..

I use that size often, so it is the first socket I check for in a set..
My SnapOn, ProTo, and Craftsman sets all came with a 5.5MM.

They offer it in the shallow, mid-depth and deep 6 point socket sets and in 12 point sets. A total of 10 different sets offer it. It's in every set I cited plus three more. So because they sell some sets that do not offer it, you'd skip buying the sets that do and go to another brand? Makes no sense to me.

Using that rationale, Snap On skips the 4 and 4.5mm socket in some of their sets - so you'd go to another manufacturer in that case also even though they offer it in other sets. To each his own I guess.

 

[Fcvapor05]

The difference between 13mm and 3/4" is out at the third decimal place. I doubt that forging techniques are to that tight a tolerance. I have used 13mm for 1/2" on occasion without any damage but if I ran up sgainst a lot of resistance I would not push it. 13mm is not that sloppy. I have found that a 1/2" socket will sometimes fit on a 13mm fastener, though a bit snuggly.

1/2" = 12.7 mm. .3 mm is .012, 12 thousandths.

For a socket to fit properly, 12 thousandths is a lot. You can easily round the head of a grade 5 bolt with a 13 mm socket.

As far as 19mm vs 3/4, as someone already said the difference is only 2 thousandths, making them basically interchangeable.

You're correct in that forging tolerances are relatively loose- but the working surfaces of quality wrenches aren't forged. The main body is forged, and then the working ends are broached to final dimensions- and broaching is a very very precise operation, 2 thousandths is a lot.

I would not be surprised in the least if quality tool companies do not use the same broaches for 19mm and 3/4" tools.

 

[Roberts210]

My S-K 1/2" wrenches won't fit a 13mm bolt or nut.

 

[T45]

I would not be surprised in the least if quality tool companies do not use the same broaches for 19mm and 3/4" tools.

I have tested mine, and ceratinly you can tell the diference between 19mm and 3/4 and even 8mm and 5/16 on good quality wrenches. A good company will actually broach SAE and Metric with the correct hardware.

That being said, there are degrees of "nocticeble" which are short of "won't fit" and "likely to cause catastrtophic failure". Mainly, they have to do with the ease of using the tool (typical of broaching patterns in general, like chamfers, which are designed to help you get the tool on and off but sometimes are unwelcome and ground off for more precise fitments).

I wouldn't hesitate to use 19mm and 3/4 interchanchibly, however, if operating under wight and space constraints, or severe financial contraints and only working on one primary SOM so the other was basically a backup set, or in single or low/infrequent use applications.

For people dealing with high volume, damaged and unkown hardware and fitments, I would make the effort to use have available both SAE and Metric tools in correct fitments.

 

[rhandwor]

If I purchase a socket set with a missing size I purchase the missing socket. SK makes the sizes as I have a 1/4 drive SK 13mm.

 

[Adam.C]

The difference between 19mm and 3/4" is not 3%, as somebody said. It is less than 0.3% or 0.26 % to be a bit more exact. I stand by my original statement. There is no functional difference between the two sizes. We are talking about 2 thousandths of an inch for a 3/4" socket.


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While I agree with your point about 19mm, what you wrote is slightly misleading:

3/4" sockets don't measure 3/4" across the flats. Ditto, bolt heads aren't exact. Adding extra slop, even a few thousandths, allows the socket to rotate further possibly bearing on the bolt's corners instead of the flats as it was designed.

I agree .002" is probably imperceptible in 19mm. But it probably doesn't take much more (percentage wise) for the socket to round a bolt head in some circumstances.

Having just left Britain, I can attest to the fact that times are tough over there and really throughout western Europe. Tougher than I think Americans realize. The pound and euro are tragically low against the dollar and people need to economize where they can. British mechanics I knew saw very few inch sized fasteners (old land rovers being the exception) so many had few or no inch sized tools. Guys who worked on Landies needed whitworth and other goofy tools and tended to be specialists.

US mechanics, despite complaints here, aren't in such dire straits. They can generally afford to own every socket known to man. I've never encountered a pro mechanic who used metric tools on SAE equipment or vice versa.

Automotive repair and restoration is a popular hobby across a pretty broad spectrum of income/demographics in the US. I didn't see that in the UK. These mechanics also seem to own every socket known to man. I sure do.

Last- I lived not far from the Haines Motor Museum and if anyone is travelling over there, that is worth a trip (skip stone henge). Ditto, no trip to Germany is complete without a visit to at least the Mercedes or Porsche factory. Both are well worth visiting. Haines had a bit of a mecca like factor for car guys, but I was surprised it wasn't a bigger deal. Over here, car guy get-togethers like "cars and coffee" are pretty amazing. I feel like americans like working on cars and have a lot more money to spend on their cars and hobbies. This is all to say, no we don't use 13mm on 1/2".