Why 1/4", 3/8", 1/2", etc.

[mulepackin]

Just curios if anyone knows the history behind the standard drive sizes. Even European manf. use SAE dr. sizes, never seen a metric drive.

 

[kartracer55]

No Idea why, but they also had, at one point, a 5/16 drive size. I have one socket. My boss has a small baby wipe box in his box full of super old snap on stuff, some of it going back to the 40's if not earlier. He has a few 5/16 drive tools as well.

If I had to guess (and thats all this is), Id say because 1/4 made more sense than, say, 9/32 drive or something like that. They just seemed to pick easy numbers and made the drive sizes. For some reason, 5/16 never caught on, probably because 1/4 or 3/8 made more sense. Measure in 8ths and 4ths instead of 16's or so.

Jim

 

[Deafautotech]

the 1/4 drive system are good design for light duty.
the 3/8 drive system are good design for medium duty.
the 1/2 drive system are good design for heavy duty for automotive
AS i own 3/4 drive set (craftsman) for heavy duty for big vehicles but also for automotive as truck and SUV that where it need strong tool without use 1/2dr and break it.

i hate to break my tools because it will hurt me or damaged other vehicle.

 

[l_bilyk]

I think the europeans use it because the sizes originated and became in the US first.... it really didnt make sense to make a whole new system in metric after one had already been established

 

[kartracer55]

I seem to recall hearing 1/2 drive refered to as 12mm

 

[Deafautotech]

No, 1/2" socket are almost fit with 13mm socket not 12mm.

 

[Charles (in GA)]

No Idea why, but they also had, at one point, a 5/16 drive size. I have one socket. My boss has a small baby wipe box in his box full of super old snap on stuff, some of it going back to the 40's if not earlier. He has a few 5/16 drive tools as well.

The odd size drives, such as the 5/16 were an anti thieft feature. You would have to steal the entire system, ratchet, breaker bar, extensions, sockets, to have something useful. During WWII these odd drive sizes were used in the factories to keep their tools at work.

Charles

 

[TNToy]

Just curios if anyone knows the history behind the standard drive sizes. Even European manf. use SAE dr. sizes, never seen a metric drive.

Many people don't realize this, but up until a certain point somewhere between the 40s and the 70s... ALL automobiles made EVERYWHERE used fractional fasteners. There were no metric nuts or bolts used in vehicles.

To top that off, the Ratchet & Socket idea was invented here and spread abroad by Snap-On... although they didn't actually invent it. So it started with SAE sizing, and everything has stayed that way to ensure compatibility.

Oh, and 1/2" is NOT 12mm. It actually works out to 12.7mm.

 

[goodfellow]

Yup -- that's it. Socket drives were standardized with the first US patents. Since "US made" tools actually meant something in the early part of the 20th century, and we produced more tools than anyone else in the World, our system became the "defacto" standard.

Same with automotive rim sizes. Even though tire tread sizes are now international metric, the rims are still sized in inches. There were a few attempts at metric rims back in the late 80's, (used by Ford and others), but that faded fairly quickly.

 

[wilbilt]

Same with automotive rim sizes. Even though tire tread sizes are now international metric, the rims are still sized in inches. There were a few attempts at metric rims back in the late 80's, (used by Ford and others), but that faded fairly quickly.

400mm rims have been used by European automakers as far back as the 1930s. I know of Peugot and Alfa-Romeo for sure, but there were probably others.

I have mounted 165-400 Michelins as recently as the mid-1980s for a German-made amusement ride at Magic Mountain in SoCal. They were used as drive/brake tires for a roller coaster or something. They are getting scarce these days.

The "TRX"-style 365mm, 390mm, and 415mm used by BMW, Ford, etc. are still easy to find. I had a set of takeoff TRX wheels and tires from a 5.0 Mustang on my Pinto back in the day...

 

[kartracer55]

Many people don't realize this, but up until a certain point somewhere between the 40s and the 70s... ALL automobiles made EVERYWHERE used fractional fasteners. There were no metric nuts or bolts used in vehicles.

To top that off, the Ratchet & Socket idea was invented here and spread abroad by Snap-On... although they didn't actually invent it. So it started with SAE sizing, and everything has stayed that way to ensure compatibility.

Oh, and 1/2" is NOT 12mm. It actually works out to 12.7mm.

I meant the drive size. 13mm would be the metric "equivalent" socket of 1/2.

I could have sworn I have heard 1/2 DRIVE sockets refered to as 12mm or so

Jim

 

[MarkH]

These became the standards years ago. In most industries coming out with a new standard that only items you make is usually the kiss of death. So if you want to ship around the world and not to a captive customer. You use the standard.

In the 70's when I took shop in school we were told to get metric that was all you would use in the next 10 years. Took 10 years before I used one the first time. So unless you have a theft type reason to pay higher prices for a new standard the old ones will be with us for a while. I do not want to buy a wrench that will not fit the boxes of sockets we have. Even electronics as big as they are Sony has learned a few times you do not make a standard by going it alone.

 

[Senorpablo]

Camera gear has a similar legacy that's hard to shake. 3/8" for tripods, and 1/4" for cameras.

It must drive the europeans crazy!

France for example has very strict standards about what products can get their seal of approval and be imported. Everything must be designed in metric, not converted to, and all language/markings must be in French.

 

[Der Bugmeister]

Many people don't realize this, but up until a certain point somewhere between the 40s and the 70s... ALL automobiles made EVERYWHERE used fractional fasteners. There were no metric nuts or bolts used in vehicles.

Hmmm...remind me again why I had to buy Metric tools to work on my old VWs...

 

[TNToy]

1. When was that vehicle made?

2. There are exceptions, of course. Metric fasteners existed then, obviously. Mainly I'm referring to the period of time where about 99.7% of the vehicles found in the US were either made in the USA, or they were British.

Both of which used what style of fastener, again?

But really, the vehicles are irrelevant. Sockets & ratchets are the topic, and we've already covered the "why" sufficiently.

 

[wilbilt]

Mainly I'm referring to the period of time where about 99.7% of the vehicles found in the US were either made in the USA, or they were British.

And of course, those freaking Renaults. Dauphine, R8, R10, etc.

A Renault R10 was my first car. They say the Corvair was bad...how about a 4 cyl water-cooled rear engine. Heavy engine, radiator and fuel tank in the rear.

It had leather seats and 4-wheel discs, but that didn't prevent me from rolling it. 3-lug wheels. It had 3-lug wheels....

As far as the fasteners, I think it had "French Metric". Nothing I had would fit them properly.

 

[Jbullfrog]

Ford was the best at randomly combining Metric and Standard fasteners on vehicles. Standard on the engine, metric in the cab, metric on the rear axle, standard on the front axle and hubs.

 

[mulepackin]

Ford was the best at randomly combining Metric and Standard fasteners on vehicles. Standard on the engine, metric in the cab, metric on the rear axle, standard on the front axle and hubs.

Ford tractors are (were) the same. Built in Canada from alot of American made components.