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[Worf]

I ordered some 3/16" whitworth nuts, expecting to get nut that would fit a 3/16" whitworth socket. What I got was 3/16"af nuts with a whitworth thread  which are tiny.
My fault or theirs?? I am confused

Should I order 7/16"af whitworth nuts (if there is such a thing)
Knowing my luck they will be far too big

[Craig T]

BS threads are measure on the diameter of the thread so a 3/16" whitworth screw will have the thread diameter of 3/16" or 4.76mm
The head size of a 3/16W hex head bolt should be 0.445" or 11.3mm across flats.

I once tried to convince someone that was using a 13mm spanner on a bolt, that the bolt he was doing up was in fact an M8 thread. He insisted, no it's not, 13mm spanner fits an M13 bolt....   

Craig.

[autorover1]

Its  normal to specify fixings by their thread size not the hexagon and  would expect any supplier to understand that all nuts are specified by their thread size .  An M6 nut fits  an M6 thread , 1/4" UNF nut has  a 1/4" thread.  If you order a 6mm bolt , its the shank & thread dia. I would send them back and tell them to send the correct ones.

[Craig T]

Pretty sure BS spanners are stamped with the thread size too so a spanner with 3/16W on it should be just over 11mm in jaw size.
This is off course opposite to the metric and UNF / UNC standard where the spanner size is the size between the jaws.

Craig.

[Worf]

So it looks like I ordered the right thing ? 

[Craig T]

So it looks like I ordered the right thing ? 

I would have said so, yes.
You could also have ordered 3/16 Whitworth flat blade, cheese head screws. No hex on those so the measurement has to be the thread size, not the head size.

Craig.

[Worf]

I would have said so, yes.
You could also have ordered 3/16 Whitworth flat blade, cheese head screws. No hex on those so the measurement has to be the thread size, not the head size.

Craig.

Yes, very true. Seller probably wasnt alive when whitworth were still used. Annoying, as I only need 6 and have been through all my jam jars

[Smokey 11a]

I once had the same sort of argument in a cycle shop, a fairly large family owned shop. The owners son was insistent that there was only one type of thread used on a bike, Metric, even thou my bike was a 1960's BSA. After I'd had a few words about him not having knowledge of what he was selling, his dad came and served me with the correct parts.

[2a_Lightweight]

Pretty sure BS spanners are stamped with the thread size too so a spanner with 3/16W on it should be just over 11mm in jaw size.
This is off course opposite to the metric and UNF / UNC standard where the spanner size is the size between the jaws.

Craig.

BS spanners are stamped with the thread size in both BSW and BSF (which use one size smaller head for same size thread diameter than BSW) for the appropriate across flat measurements.

In recent years there are more and more BSW/BSF bolts and nuts being made with non standard head sizes - I presume due to availability of the raw stock in BSW/BSF sizes, so A/F and even metric stock is used to manufacture BSW/BSF fasteners.

I work with BSW/BSF daily in my employment as majority of our equipment is BS.

[Calum]

All we use at work is BSW. We sometimes get batches of nuts made out of the wrong hex size but it's pretty rare, I think I've actually only seen it once with a box of 1/2" Whit nuts with 19mm across the flats.

I will point out that a 3/16" Whit nut will actually fit an 1/8" Whit spanner which is 0.338" across the flats, same as 3/16" BSF. During the war the head size of Whitworth fasteners was reduced to match the BSF size for the same thread diameter. It never really changed back but the spanners always remained the same so it can get confusing.

[alchad]

Take a copy of this, laminate it, and stick it in your workshop/ wherever.

https://dbtc.co.uk/index.php/nuts-bolts-spanners

Alchad

[Gibbo103]

So it looks like the supplier has correctly sent 3/16 nuts as requested as these would have a thread diameter of about .18” or about 4mm.

[w3526602]

Hi,

Way back when, everybody made their own nuts and bolts. presumably filing the flats to suit themselves, and to fit the spanner they had made (or vice versa)

I believe it was Mr Whitworth who standardised  spanner sizes, but using some complicated formula (anybody?) for the width of the spanner jaws, and a somewhat coarse thread, with a "thread angle" (or whatever it's called?) of 55 degrees, and a hexagon A/F (across flats) based on his mother-in-laws shoe size (or something like that) I'm joking, I think.

Sometime later, possibly due the war, and the need to save raw materials, USF and USW were invented, with smaller hexagons. I can't remember if the thread angle was changed to 60 degrees. and the head was reduced, but rationalised, so that a 1/4" Whitworth  spanner would fit a 5/16" BSF nuts, too. I don't know if the same applied to other sizes. You needed to be a rocket scientist, to calculate the spanner size needed for each thread size.

Enter WW2 (or was it WW1?), and the Yanks joining (on our side), and bringing their ANF/ANC (or was it UNF/UNC?) with them. They had rationalised things even further, so that the thread angle was now 60 degrees, but I have no idea about thread pitches. The A/Fs were also rationalised by rounding off to the nearest 1/16". That way, nuts and bolts are identified but their thread sizes, but spanners are identified by their AF. Character building.

Metric followed suite , but in 1mm increments for bolt diameter, and spanner AF ... which are entirelty different.  EG ... A 6mm thread diameter nut or bolt will require a 10mm AF spanner (usually).

So no more rolling up to the stores window and asking for a 1/2" AF nut.

I will ignore cycle thread (very fine pitch), but ir will be worth while having both ring and open ended spanners, sizes OBA thru 4BA (even numbers), wrapped in an Irish linen handkerchief, and kept in SWMBO's knicker drawer. You won't want them very often, but when you do, you nwill want to know where they are.

I'm happy to be corrected. I know I've made one incorrect statement, but can't be naffed to correct it.

602

PS... BA is short for British Armstrong ... I think.

"U" as in UNF stands for UNIFIED. But should it be "A" for AMERICAN?   

Overtaken by Gibbo ... I think 3/16" is 0.185" (its been a long time ...  ), but a couple of long handled ring spanners soon sort out a 5 thou difference.

[34058]

A while ago I got some 5/16" UNF brass manifold nuts so I would not have to deal with rusted and seized steel nuts ever again.  Annoyingly they had been made out of 13mm hexagonal stock and not 1/2" stock, so I have to remember to get out the metric sockets when I am working on the exhaust system.

More recently I got some more brass nuts that are 1/2" Across the Flats but have not yet got around to swapping them over.

David

[Worf]

So it looks like the supplier has correctly sent 3/16 nuts as requested as these would have a thread diameter of about .18” or about 4mm.

I agree, what the supplier described was exactly what I wanted.
What he actually sent were physically far smaller, maybe 1/8w  , so it looks like just a picking error.

I just wanted to check that the fault wasnt mine before I returned them, hence my original post.