PDA

View Full Version : What's up with 18mm?



MotorradMike
12-12-2009, 02:16 PM
I own a single 18mm box end wrench, only because it came on the other end of the 19mm I wanted.

I've never used it in 35 years.

While looking for a stubby set to use on my lathe, I notice most sets come with an 18mm, some of them leave out the extremely useful 13mm and 19mm.

Is there something(else) I don't know?

Dr. Rob
12-12-2009, 02:44 PM
Idunno, but it bugs me bigtime that they always come in sizes like 10/11, 12/13, 17/18 and so on. Wouldn't it be easier for us all if they came in 10/13, 17/19 ?
.

Mark Hockett
12-12-2009, 02:51 PM
18mm is a very common size in the automotive industry. 13mm and 19mm will cross over to 1/2" and 3/4" so that might be why some sets leave those out.

doctor demo
12-12-2009, 03:40 PM
While we're on the subject of odd wrench sizes. How often do ya use the 17/32 or 19/32 or 25/32 end wrenches that come in the Craftsman sets? I have had Mine for thirty years or longer and can't recall ever reaching for one of them.

Steve

motorworks
12-12-2009, 03:44 PM
I use 18mm alot
The first few times I came across it I did not have the wrench
Off to Canadian Tyre, etc and no one had it.
Had to get it through Snap-on
It was $$.

jihe
12-12-2009, 03:58 PM
In Sweden most of the smaller sets lack the 18 mm. On the other hand, Sweden is _very_ metric, so I wouldn't consider it really strange since the standard fasterners in that size are rare. You would have to look really hard to find an 18 mm nut in any hardware store. Of the small sizes I'd consider 8, 9, 10, 11, 12, 13, 14, 15, 17, 19, 20, 21, 22 and 24 to be "standard".

Richard-TX
12-12-2009, 04:18 PM
While we're on the subject of odd wrench sizes. How often do ya use the 17/32 or 19/32 or 25/32 end wrenches that come in the Craftsman sets? I have had Mine for thirty years or longer and can't recall ever reaching for one of them.

Steve

There was one fastener on a 70's Mopar vehicle that required a 19/32" wrench.

Old Delta Machinery uses n/32" nuts quite often.

n/32" was part the the whole National Heavy series of fasteners way back when.

Peter S
12-12-2009, 05:03 PM
In NZ you can get normal M12 hex bolts with 18mm or 19mm heads, just as M10 can be had with 16mm or 17mm head.

bruto
12-12-2009, 05:46 PM
I have never quite understood why 18 mm. became so popular in automotive fasteners, but it did in the 80's. My 88 chevy truck uses a bunch of them, and so do Jeep Cherokees. Just about every fastener in the steering linkages, etc. is 18. My initial guess is that it is used precisely because there is no common SAE "close-enough" equivalent, so it forces the use of a proper sized wrench.

Given how common 18 has become, I continue to be surprised at how few sets come with it.

bruto
12-12-2009, 05:51 PM
While we're on the subject of odd wrench sizes. How often do ya use the 17/32 or 19/32 or 25/32 end wrenches that come in the Craftsman sets? I have had Mine for thirty years or longer and can't recall ever reaching for one of them.

Steve

19/32 will sub for 15 mm. in a pinch, and you might be able to put a 17/32 on 14 if 9/16 is too sloppy. I don't recall ever needing a 25/32.

clutch
12-12-2009, 05:52 PM
I had to buy an 18 mm to work on an Okuma lathe. Only machine I've ever used it on.

Clutch

Willy
12-12-2009, 06:14 PM
I've had to buy 18mm wrenches and sockets separately in order to fill out my "sets".
I too use 18mm a lot.
It really pisses me off when I purchase a "set", and the "set" isn't complete.
It's like buying a 1/4"-1" set and having some twit in accounting make the decision for me that I probably won't use the 11/16" much so "we'll just leave that one out"!
Same with metric, that's why I want a "set". I'll make the decision as to what I need.
Darn marketing dorks don't use wrenches, but then make the decisions as to what those that do are going to use.
I hate also to use a wrench from one set because it's close enough to the one missing from another set, because it's close enough...sometimes close enough isn't good enough.

Carld
12-12-2009, 06:37 PM
Hmm, don't know why that is. When I was a diesel mechanic I bought every open end, combination, offset and box wrench from 1/4" to 2" and still have them. I used all of them one time or another. Don't even ask about the socket wrenches and impacts I have and Ohh, the 600 ft lb torque wrench I don't use anymore thank God.

Tool crazy, Uhuh, Uhuh, the white coats are after me :eek: :D

CountZero
12-12-2009, 07:03 PM
Just wait, many have started using 18 instead of 19 and 12 instead of 13 and son on apparently huge savings in material cost...

jdunmyer
12-12-2009, 09:36 PM
I bought my first metric wrenches back in about 1967, when I got a Honda motorcycle. Always wondered why there was a 13mm included....until one day a friend asked me to do something to her VW Beetle. Hmmm... a 12mm was too small, and a 14mm was too big...but the heretofore unused 13mm was just right!

About 1992, I bought another Craftsman tool set, and it included an 18mm wrench and socket. Never had a need for them until getting my imported milling machine vise. Wanted one of those 'spider' handles for it, bought one that had a 5/8" hex, bored it out to accept the pressed-in 18mm socket from the set.

Have never had a need for 18mm otherwise, even having owned VWs since 1980.

J Tiers
12-12-2009, 10:19 PM
While we're on the subject of odd wrench sizes. How often do ya use the 17/32 or 19/32 or 25/32 end wrenches that come in the Craftsman sets? I have had Mine for thirty years or longer and can't recall ever reaching for one of them.

Steve

I have an S-shaped short wrench with 19/32 on one end and 0.5" on the other. Only about 5 or 6 inches long, if that.

The 19/32 is perfect for the Logan lathe compound t-bolt nuts........ It's like it was made for that machine, but the wrench is not from Logan

Don Young
12-12-2009, 10:42 PM
When I and my two sons started working on VW Beetles and metric motorcycles we immediately discovered that a 10MM wrench was essential since neither 3/8" nor 7/16" was close enough. After using the 10MM and English wrenches for a while we finally decided we needed to get a metric set. Bought a nice looking set at Kmart that went from 8MM to 19MM, with one exception: no 10MM! Worked fine for us but I have always wondered what the logic was.

gmatov
12-13-2009, 12:17 AM
I don't know why the 32s are included today, either, BUT, Ford in the old days DID use the old method of sizing bolt heads, half again the size of the bolt.

Today, 5/16 is a 1/2 inch wrench. Large head. Originally 15/32. 7/16 is 11/16 wrench, originally 21/32. 9/16 is 13/16, used to be 27/32.

25/32, I can't place. If you have one, it is a bastard size.

Those wrenches came in the toolkit shipped with every Model A or T. I wouldn't be surprised if they were also used on other makes in the old days.

They were the standard sizes, so far as I know.

Bolts and nuts, of course, come in other head sizes. When I left the US Navy, from the Black Gang, about 40 years ago, failed the test at Cat dealership because we used different size fasteners for different applications. HP steam used large head size and nut size for HP fittings.

Question was wrench size for 3/8 bolt, I wrote 9/16 or 11/16. More sizes, same thing. Flunked the test.

Went to Elliot, worked HP steam, we had THREE wrench sizes per bolt.

Steel mill, similar, Grade A325 bolts, all sizes were 1/8 over nominal. 1/4 should be 7/16, A325 was 9/16, 5/8 should be 15/16, was 1 1/16.

Don't bitch about size. There is a reason, so THEY say.

Cheers,

George

Andrew_D
12-13-2009, 01:25 AM
I seem to use the 18mm more than the 19mm. Most of our newer John Deere machinery that is metric uses 18mm. Same for our newer Kenworth highway trucks - they use 18mm as well.

Andrew

madokie
12-13-2009, 02:19 AM
16mm combo is hard to get now,7mm has been dropped from allen wrench sets,i need that 7mm working on my lincoln rear disk brakes on my stang 5.0

loosewatches
12-13-2009, 02:21 AM
A nineteen millimeter nut is actually (normally and new) slightly larger than 3/4 inches.

I think there may be a stupidity factor included.

Having spent some time wrenching in Austria, I developed the complex idea that:

1. Where the 3/4 inch wrench may fit a 19 millimeter nut there they
a. don't have them
b. don't care

2. Were the 18 millimeter wrench more easily to fit a nut which can be more laboriously produced (what with the threads remaining the same)
a. it should (and therefore must)
b. replace everything else for the American ease.
c. by American Imperialists in an effort to replace the future
d. of (proper) Metric Nutz
2.a. (I may not have a proper grasp on the nut)

-loose

platypus2020
12-13-2009, 02:29 AM
While we're on the subject of odd wrench sizes. How often do ya use the 17/32 or 19/32 or 25/32 end wrenches that come in the Craftsman sets? I have had Mine for thirty years or longer and can't recall ever reaching for one of them.

Steve


Old Allis-Chalmer and Farmall tractors

jack

bruto
12-13-2009, 11:42 AM
I am guessing that the main reason for 18 mm. heads is economic, though it's amusing to spin a little conspiracy scenario in which wrench and fastener manufacturers collude with car makers to force us all to buy more stuff. Most likely at some point a bean counter determined that reducing the head size on umpteen zillion tie rod ends, etc., even though the difference is virtually immeasurable on one nut, would reduce the cost of materials by some measurable amount, simply because of the scale. It's the same philosophy that makes manufacturers cut corners and annoy us with glitches that would cost pennies to improve, and on another scale why some manufacturers have made the cynical determination that it's cheaper to settle the lawsuits of victims than to improve even fatal flaws.

Japanese manufacturers have been using 12 and 14 where others used 13 and 15 for many years, presumably for the same reason. Way back in the stone age my old Peugeot 403's used 12 where we'd now see 10 or 11, and 14 where we now see 13. Nice big beefy bolts, and they supplied a high grade set of tools too, including the best small water pump pliers I've ever had.

One of my Jeep Cherokees used 7 mm allen bolts for the front calipers. I have buckets of allen wrenches, pounds of them. Allen wrenches of all sizes and shapes, little stashes of them everywhere, full sets and broken ones, bike bags bulging with them, but I don't think I ever worked on that thing without having to hunt for a half hour or so for the one, straggling 7 that lurked somewhere. I even had to regrind a wrench once. :(

Paul Alciatore
12-13-2009, 01:26 PM
I am guessing that the main reason for 18 mm. heads is economic, though it's amusing to spin a little conspiracy scenario in which wrench and fastener manufacturers collude with car makers to force us all to buy more stuff. Most likely at some point a bean counter determined that reducing the head size on umpteen zillion tie rod ends, etc., even though the difference is virtually immeasurable on one nut, would reduce the cost of materials by some measurable amount, simply because of the scale. It's the same philosophy that makes manufacturers cut corners and annoy us with glitches that would cost pennies to improve, and on another scale why some manufacturers have made the cynical determination that it's cheaper to settle the lawsuits of victims than to improve even fatal flaws.

Japanese manufacturers have been using 12 and 14 where others used 13 and 15 for many years, presumably for the same reason. .....(

Yes, this was my reasoning precisely. Just some bean counter trying to get a bonus. Or save his/her job.

But, English/SAE fasteners have standards. Published standards. Don't metric fasteners also have standards? Or are they just being ignored for economy?

deltaenterprizes
12-13-2009, 01:53 PM
I have a centering vise with a 18mm SQUARE on the shaft to tighten the jaws, pain in the arse to make a speed handle for it.

Doozer
12-13-2009, 04:02 PM
Ya know what else is odd, 7mm bolt thread.

--Doozer