Thread: Spanner sizes

The size on whitworth spammers relates to the thread size not the across flats like a normal spanner. 1/4" whitworth still has a od of 1/4". Most stuff made in the 50's and earlier has wit worth fasteners. I'll post more later when I'm on my computer.

Some WW spanners have dual markings, the size of the bolt heads and nuts for WW fixings was reduced by one size during WW2 so the head of a 1/4" bolt is bigger pre-war.
A 1/4" tap is a 1/4" tap no matter if it's UNC, UNF, Whitworth etc. The WW tap will have a 55 degree threadform, the UNC/UNC (and metric) will be 60 degrees.

Thanks guys, The forum is such a knowledge bank!

Originally Posted by Gavin Newman

Some WW spanners have dual markings, the size of the bolt heads and nuts for WW fixings was reduced by one size during WW2 so the head of a 1/4" bolt is bigger pre-war.
A 1/4" tap is a 1/4" tap no matter if it's UNC, UNF, Whitworth etc. The WW tap will have a 55 degree threadform, the UNC/UNC (and metric) will be 60 degrees.

I never knew that they changed head sizes. You learn something every day.

Originally Posted by snapatap

I never knew that they changed head sizes. You learn something every day.

It is still happening!

19 mm A/F to 18
17 mm A/F to 16
13 mm A/F to 12

I wonder when they will start on cap screws? Metric cap screws have a larger head than the roughly equivalent imperial ones (1/4"-6 mm; 5/16"-8 mm; 3/8"-10 mm) so this is an easy way to quickly identify them.
Mm.

Originally Posted by Metalman

It is still happening!

19 mm A/F to 18
17 mm A/F to 16
13 mm A/F to 12

That is just the difference between JIS and DIN and ISO..

You buy a japanese devise and it had bolts with 12mm heads, you buy some spares in AU and they will have 13mm heads... And metric was supposed to be standardised..

There is nothing more annoying, repairing something, you are in some god forsaken position to get a last bolt out, every bolt you pulled out had a 12mm head.. You are feeling around with the socket wondering why it is not going on... Yes someone replaced it with a 13mm headed bolt...

And the reason the Asia market don't use 13mm heads.
Is because it's bad luck the number 13 that is

As has been said before there are two Whitworths so you need two different set of spanners and another for Imperial

The bodger's guide to spanner sizes.

http://www.scribd.com/doc/226985798/Spanner-Size-Chart

Just buy a set of shifters.... If you round any heads off with them, buy a set of stillsons...

Originally Posted by Gavin Newman

Some WW spanners have dual markings, the size of the bolt heads and nuts for WW fixings was reduced by one size during WW2 so the head of a 1/4" bolt is bigger pre-war.
A 1/4" tap is a 1/4" tap no matter if it's UNC, UNF, Whitworth etc. The WW tap will have a 55 degree threadform, the UNC/UNC (and metric) will be 60 degrees.

Except pipe threads, e.g. BSPP 1/4 (Aka G1/4) is a touch over 13mm (http://www.ring-plug-thread-gages.co...read-data.html)

Originally Posted by .RC.

Just buy a set of shifters.... If you round any heads off with them, buy a set of stillsons...

Nope, a true farmer would use multigrips... nothing hi-tech like stillsons...

Ray

And then you get the bastardised standards, my long gone and largely completely unlamented Morris had bolts in the engine that had metric threads but Whitworth sized heads, I was told that the tooling in use in the factory at the time came from France, hence the metric threads.

My old (1954) Land Rover uses Whitworth sizes, I've got a set of old spanners and sockets. By enlarge, as a rule of thumb there is one size different between imperial and Whitworth. For example, if you look at something and think its a 1/8th then you'd need a 1/4 Whitworth to a compadre the bigger head.

As for Asian metric bolts and sockets, well they just do my head in. Growing up in Europe with ISO standard metric constantly sees me reaching for something that's 1mm too small. Grrrrrr


Thx
Jon