Not a very profound question but I was doing a bit of fix-it stuff.and really thought for the first time that my 1/4 inch bit holder I was using is made by Wera. It made me wonder if they make them especially for the US or if it’s a common tool that kind of got grandfathered in as an artifact using non-metric measurements.
I know the smaller hex bits are 5/32 drive,which happens to also be 4 MM, so that one seems agnostic, but 1/4 inch doesn’t match closely with anything useful.
Bit or socket drives still come in 1/4 , 3/8 ,1/2 or 3/4 inch etc down here in Australia., I’m not aware of any metric sockets that don’t fit a imperial drive.
Yes, but we call them 6.35mm drives. No problemo!
FWIW, in the UK, we still measure the wheel rims on our cars in inches but the width in mm. So my car runs on 235/40/R19. This tells me that it is 235mm wide, has an aspect ratio of 40%, and has a 19" rim.
My imbus(Allen) keys are metric. They are mounted on a 1/4 inch square driver in my ratchet set.
We mix and match, piping is often sold in inch diameters (called “thumbs” as in “een acht duims pijp”)
Carpentry is also mix and match, panels are 8x4ft (2440x1220mm) beams are also often sold and named in inches.
Car wheels are 18inch 225mm 55mm high
bicycle wheels are often called 18 inch but the tire width is mostly measured in mm. “700x30 and so”
We do it the same here in the US, which I’ve always thought and odd mixture. Metric, imperial, and computed!
I think there’s some confusion here.
You’re referring to sockets and other things that have internal square drives that conform to ASA B5.38-1958 (now ANSI B5.38). As you note, there are a handful of dimensions for the square drives, the most common being 1/4 inch (1/4 inch X 1/4 inch square), 3/8 inch, and 1/2 inch. Common drive tools include manual ratchets, impact wrenches, breaker bars, and torque wrenches.
The OP is referring to screwdriver bits, drill bits, and other things that have an external 1/4 inch hex shank. Common drive tools include impact drivers and hand drills. As far as I know, the 1/4 inch dimension is standard throughout the world for the hex shank.
I tried to find a standard for the 1/4 inch hex shank (e.g. ANSI standard), but couldn’t find one.
Pipe sizes in metric are conversions from English systems. The same standard sizes are used
Camera tripod thread is still universally 1/4" Whitworth (though some makers cheat and put 1/4" UNC on it instead, mostly it works)
Whitworth. Now, that’s a name I’ve not heard in a long, long time. (Shudder).
Yup here in Australia we’d call it 6mm hex drive but I assume it’s actually 1/4" aka 6.35mm.
Samd for die grinders - 6.35mm round collet, interchangeably called 6mm or 1/4"
Out of curiosity I measured the shank height (flat-to-flat) on bunch of them. Most were around 0.248 to 0.249 inches.
A 2002 patent (6352011B1) for a two-ended screwdriver bit says the standard is ASME B107.4, and that the shank height should be between 0.248 and 0.250 inches.
A friend of mine who was on sabbatical in Norway needed a 2 x 4 piece of lumber and asked the clerk in front for a 5 x 10 cm piece and heard the clerk ask the back room to bring a 2 x 4.
Here in Oz you can ask for a two by four, or a 45 by 90. Even the millennials serving know what you are asking for.
What is interesting is that the 2x4 inch is the nominal raw lumber size. But 45x90mm is the planed size. Both are the same actual thing. You can’t ask for a 5cm by 10 cm or 50x100mm. it doesn’t exist.