Author Topic: key sizes  (Read 712 times)

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Offline ManfrerdSt

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key sizes
« on: 15 Jun 2017 at 14:34 »
Hi all

Does anyone know the year of conversion from the key sizes?
From WHITWORTH (WW) to BRITISH STANDARD (BS)?
From BS to AF?

Regards
     Manfred


Offline cardan

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Re: key sizes
« Reply #1 on: 16 Jun 2017 at 00:29 »

Hi Manfred,

No, not exactly.

Before the first war, Whitworth hexagons were larger than they are now. I've read that the change to smaller hexagons was as a result of war-time shortages, but I don't know this for sure. Whatever, the larger size nuts are rarely seen post WW1.

So: a "real" (say pre-WW1) 1/4W nut (to fit a Whitworth thread on a 1/4" diameter rod/screw) is larger than we find today, in fact it is the same size used by 5/16" British Standard nuts today. Thus we find spanners (wrenches to an American, not often "key" in English but we know what you mean) labelled 1/4W-5/16BS.

"AF" just means Across Flats, so a 7/16" AF nut is 7/16" across the flats of the hexagon. A 7/16AF spanner is just slightly too small to fit a 3/16W-1/4BS nut, and a slightly loose fit on an 11mm nut.

The hex sizes used depend on the manufacturer, but not always in an obvious way. Belgian FN motorcycles - pre-WW1 - used all imperial AF hexagons (1/2", 9/16" etc.) where you might expect to find mm sizes.

Of course the threads that go with the hex sizes... no wonder we're confused. I have a new favourite: the c1907 Berlin-built vehicle I'm working on at the moment uses threads like 10mm-16tpi (threads per inch). Really!

Cheers

Leon

Offline ManfrerdSt

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Re: key sizes
« Reply #2 on: 16 Jun 2017 at 09:21 »
Hi Leon,

That there is a difference between "before WW1" and "after WW1", I did not know.
I thought there was a change from "WW" to "BS" around 1935, then a change from "BS" to "AF" after WW2.
I have read, during the WW2 there were great problems with the supply of spare parts, because "WW" or "BS" was confused with "AF".
The exact story would interest me very much.
Threaded outside a norm was normal until the dreisiger years with us.
e.g. "Wanderer" has used a lot of threads outside the standard. I think you wanted to bind the spare parts sales per se.
But also with Douglas there is a 25tpi 5/16 "or 17/64" or a 3/16 "x 27 tpi.
What do you mean "the c1907 Berlin-built vehicle"

Regards
     Manfred


Offline cardan

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Re: key sizes
« Reply #3 on: 16 Jun 2017 at 11:21 »
What do you mean "the c1907 Berlin-built vehicle"
It's a bit of a secret: three wheels, very like a Cyklonette, but with a single-cylinder 610cc overhead valve motor built in Wallstrasse, Berlin, c1907. It is the only survivor of an an otherwise completely unknown maker. Even the man who wrote the book about cars built in Berlin had never heard of it. I'll say more when it's finished.

Re British Standards: It seems the British Institute of Standards started around1901, and produced thousands of standards for all sorts of things. By 1913 (I'm just flicking through Motor & Gas-Power Pocketbook, first edition 1913), there was a standard (BS 39) that describes nuts and bolts. BS Whitworth and BS Fine are both described, and in 1/4" (for example) both have "big" hexagons (33/64") as used on "modern" 5/16" BSW and BSF fasteners. By BS 1083 (published in 1965) the hexagons were the "modern" small sizes. I guess we could find out when the Standard changed, but as I said my experience is that the large hexagons were rarely used after WW1.

Cheers

Leon

Offline oil baron

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Re: key sizes
« Reply #4 on: 18 Jun 2017 at 02:45 »
Hi Leon
Big hexagons may well have gone out of fashion for a lot of automobile applications after WW1, but they were still used in Marine Engine applications certainly well into the 1980's.

Cheers
SteveL.
Steve L

Offline cardan

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Re: key sizes
« Reply #5 on: 18 Jun 2017 at 03:25 »

Hi Steve,

That's interesting. Room to rust without rusting through? Also often found on wooden stuff like horse-drawn vehicles. A few years back I bought a stock of unused "proper" (large, and chamfered on one side only to the BS) 1/4 BSW nuts for my early Lewis motorcycle that used them everywhere. Perhaps they came from a marine source.

It would be fun to know when the British Standard for hexagon size changed - some time between 1913 and 1961 - but there's nothing to force anyone to use them. Fashion is a powerful thing, as are commercial reasons. Let's face it: all those beautiful Douglas threads (17/64-27 and its friends) never appeared in a British Standard!!

Cheers

Leon

Offline oil baron

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Re: key sizes
« Reply #6 on: 18 Jun 2017 at 10:27 »
Hi All
If you are confused with all this talk of thread types and bolt head sizes etc, it gets worse!
Crossely's of Manchester, who used to make cars and trucks and engines for small ships and railway engines, in the late 1950's onward they manufactured French Pielstick Marine Diesels under licence.  The original French engine of course was all metric and used metric bolts which had large hexagons. The Crossely built engines used metric bolts but with generally a Imperial A/F sized head, though there were some larger sizes which still used a whit. based sized spanner. Presumably the use of imperial sizes was due to the British ships in the  1960's, were not normally equipped with metric spanners as a rule, and of course the metric ISO standard  metric bolt had not come into general usage.  On the ship over the ensuing years, replacement parts were needed and not necessarily sourced from Crossley's but from other suppliers, which led to the odd metric headed bolts creeping in, then of course there was the choice of large headed metric bolts and the auto type bolt with a smaller hex. head.  Being that the vessel was built in a British yard, things like pipe flanges may have had Whit/BSF or UNC/UNF Bolts fitted when new, as  But over the years some flanges even ended up with a mixture of both.  So whatever you job had to do on board required a bucket full of spanners of every shape and size.  Thank god they did not have any Douglas sized threads to deal with, it was bad enough dealing with the common thread types and the variation in bolt head sizes.
Cheers SteveL.
Steve L

Offline douglas1947

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Re: key sizes
« Reply #7 on: 18 Jun 2017 at 19:30 »
Hi all,

for special purposes there was sometimes the use of the "original" bigger hexagon of WW, for ex. Panther used for engine crankcase for all 4-strokes 1/4" studs the big nuts until end of production in the sixties!

Michael

Offline cardan

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Re: key sizes
« Reply #8 on: 19 Jun 2017 at 06:38 »

I'll be checking out Panthers at the next rally! Correct nuts and bolts are nice.

Re Douglas, the 5/16-25 nuts so commonly used come in (at least) two hexagon sizes: the "standard" 1/4W-5/16BS size, and the smaller 3/16W-1/4BS - different sizes for different applications. I'm not sure how they varied by date.

That said I have a dozen or so 5/16-25 nuts with 1/2" AF hexagons. They are old, nickel plated and nice, but no idea where they might fit in. Maybe Australian-made replacement parts.

Worth a link to Chris's marvelous post on Douglas threads, in the Technical Articles section of this forum: http://www.douglasmotorcycles.net/index.php?topic=1102.0

Cheers

Leon

Offline Doug

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Re: key sizes
« Reply #9 on: 19 Jun 2017 at 18:23 »
I have encountered two of the 5/16-25 hex sizes. The one with the 1/4W-5/16BS wrench size (0.525" across flats) is part # 711. The other is 7/16" across the flats, and is part # z385. None of the later samples seemed like they would suit a 1/8W-3/16BS wrench (0.340" across flats) 3/16W-1/4BS (0.445 " across flats). If anything they were all slightly smaller than 7/16; but possibly them made them considerably undersized. They did not appear to do so with the bigger nuts, which where usually quite close to the Whitworth hex size, hence my believing they are 7/16 rather than Whitworth. Both are 'low' part numbers, which date them back to the 2-3/24hp era. During the Dirt Track era, # 711 was being used on things like the rocker arm perches, magneto studs, and some of the crankcase bolts. The smaller hex of # z385 was being used on the two lowers crankcase bolts due to clearance issues and for the same reason for the cylinder head nuts.

-Doug

[edit. 20Jun17. -Doug]
« Last Edit: 20 Jun 2017 at 15:51 by Doug »

Offline cardan

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Re: key sizes
« Reply #10 on: 20 Jun 2017 at 10:02 »
The other is 7/16" across the flats, and is part # z385.

Hi Doug,

That's interesting. I agree that the larger 0.525" size is the more common hex on the 1920s bikes.

Is there a drawing to say 7/16 across flats ofr the smaller version? 7/16 is 0.4375", while 3/16W-1/4BS is about 0.448", so usually a 7/16 spanner is just a little small to fit a 3/16W nut unless the spanner or the hexagon is worn, and the Whitworth spanner is loose on a 7/16 nut. There's only 10 thou/0.25mm in it. I will study my collection of Douglas nuts when I get the chance.

Re smaller nuts: on British bikes (I've fiddled with quite a few) the BS hexagon size 1/8W-3/16BS (0.340" or so) is very rarely (if ever) used. Instead 3/8AF (0.375") is usually used as the next size down. Strange, but true. 

Cheers

Leon

Offline Doug

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Re: key sizes
« Reply #11 on: 20 Jun 2017 at 15:47 »
Leon,

No, I have not come across a drawing for the nut # z385. The observation was based on measuring original nuts and I did not find any that approached 0.445 inch across the flats of 3/16W-1/4BS. (The maximum across the flats dimension given by the table I am using.) The same dimension is used by the OHV cylinder port nuts #707 (17/64-25 thread).

Ignore the comment in the previous post about 1/8W-3/16BS, I was looking at the table of Whitworth nut dimensions and copied the info from the wrong column in confusion. However, Douglas did use a smaller nut for the timing cover on the OHV machines like the DT. This is part #706 and likewise must date back to the 2-3/4hp days. I have these as 3/8 inch across the flats, and likewise it does not seem Douglas was using a Whitworth hex dimension (0.340 inch). Perhaps it was just not threads that Kingwood was using to keep it propitiatory, but were using aberrant hex sizes. Or maybe they bought a tremendous job lot of hex bar in fractional dimensions and were still using it up in the late twenties!

-Doug

Offline cardan

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Re: key sizes
« Reply #12 on: 21 Jun 2017 at 03:25 »

Hi Doug,

In my 5/16-25 small-hexagon tin, the best nuts (most original-looking, with original nickel and no damage) have 0.445" hexagons (3/16W-5/16BS). These are quite tall - 0.34-0.35". A 7/16 spanner will not go on these.

Of the rest of the rabble, there are certainly some with 7/16AF hexagons. Not sure if these were originally used in the Kingswood factory, or if so when. Note that 7/16AF and 3/16W-5/16BS are the only two AF-BS hexagons that are easy to confuse. My 1913 pocket book lists the 3/16W hexagon size "to the nearest 1/64"" as "7/16", so maybe 7/16 was deemed close enough.

In summary: probably Whitworth-BS hexagons in the larger sizes, 3/8AF hexagons for smaller nuts.

Cheers

Leon

(In magnetos, and on some handlebar levers, the hexagons are sometimes BA - British Association - but that's another story!)


 

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