Odd

You can always use a 3/8 Whit (7/16 BSF) socket - only a thou' or so smaller.

What's that? Some people don't have Whit socket sets? Nonsense...

The 14 is often missing too.

Surprised at 18mm - I use mine a lot on BMWs. 20mm is a size I never come across. And I don't think I've ever used a 23mm.

Which makes the set utterly useless for Japanese cars / bikes as Japanese JIS 10mm bolts have 14mm heads.

JIS 4mm bolt 7mm head, same as Euro DIN, ISO/ANSI. JIS 5mm bolt 8mm head, same as Euro DIN, ISO/ANSI. JIS 6mm bolt 10mm head, same as Euro DIN, ISO/ANSI but many older European cars used 11mm. JIS 8mm bolt 12mm head, Euro DIN, ISO/ANSI 13mm. JIS 10mm bolt 14mm head, Euro DIN 17mm, ISO/ANSI 16mm. JIS 12mm bolt 17mm head, Euro DIN 19mm, ISO/ANSI 18mm. JIS 14mm bolt 19mm head, Euro DIN 22mm, ISO/ANSI 21mm. JIS 16mm bolt 22mm head, Euro DIN, ISO/ANSI 24mm.

The socket/wrench sizes you really don't need are 9mm, 15mm, 20mm, 23mm, as they aren't part of ISO/ANSI/JIS/DIN standard.

Smaller head saves weight and material cost. Money goes on quality, nearly all Japanese nuts/bolts are expensive forged flange head and don't have washers. Even self tappers that go in plastic parts. Saves time and cost on assembly line as they don't have to put the washer on the bolt. Saves space, time and cost as they don't have to kit the line out with boxes of washers. Don't have the pesky things running around the floor when dropped, which also saves on time spent sweeping up. Won't make a car full of rattling random dropped washers.

Japanese hex socket cap screws use washers and places where a spring washer is used (like brake caliper to knuckle) they use regular bolts.

It's been well over 40 years and still the Euro/USA haven't caught up/on. Too many bean counters saying flange head too expensive.

Cannot agree that 15 is not needed, many cars use 15, including Ford.

You need 16mm too, much of the clutch change I did last week on a Renault Megane was 16mm (I cheated and used 5/8")

and 11mm, that was on the clutch cover bolts.

The DIN standard is 19mm (extremely close and interchangeable with 3/4").

I've probably used an 18mm socket twice in recent years, but truly lost count the number of times I have used a 19mm. Even then one occasion might have been on a 11/16" bolt head.

The ISO standard for M10 is 16mm, whereas I don't recall ever using this size in favour of the 17mm DIN standard.

Not my experience.

Yet I have used a 15mm quite a few times, wheel spindle bolts on a bike for instance.

IMHO, you can never be sure. Depending on the market the tools are aimed for and where they are made.

A recent set of (lowish price) combination spanners from Lidl had all the sizes from 6 - 21mm, except 20 mm.

But do you have BA ones? ;-)

Please sir, I do. Last used on a Villiers engine magneto (IIRC)

Why do sets of Allen keys not have a 7mm? Needed for old Escort front calipers.

I (and probably many others) have an Elora socket set, acquired with Embassy coupons in 1965 or so. BSF, Whit, etc. The container eventually succumbed to tin worm, so they're now in a fancy plastic case along with all the metric sockets, adapters, torque wrenches and so forth.I think there are some BA spanners hidden somewhere in the garage.

I have a partial set of BA taps and dies, up to 11 BA, inherited from my grandfather in about 1964.

I thought that was to discourage home mechanics

Of course - well 0-8, anyway, including all the odd numbers.

And I keep a 1/8 Whit (3/16 BSF) socket with them, because Sir Henry insisted his 2 BA nuts and screws should have 0.338" A/F hexagons, not the normal 0.324"

Some VWs had 15mm head bolts on front brake calipers. Had to buy a seperate socket for that.

And VW valve clearances on the EA111 engine before hydraulic tappets. Another odd tool purchase.

I find 15mm crops up quite frequently!

On Mon, 19 Mar 2018 09:09:01 +0000, MrCheerful wrote: enault Megane was 16mm (I cheated and used 5/8")

Yup, as does 10mm, 11mm, 12mm & 13mm on the unions.