Thread: 11mm nut no such thing

Originally Posted by Pete F

I'm doing my bit buy buying metric however

If it helps ease your pain, I only specify metric fasteners except where there's a specific non-metric linear adjustment required, or where I have to incorporate a non-metric threaded component. Fight the good fight!

Originally Posted by Pete F

Anyway, I was hoping somebody could explain why whitworth is still used so extensively for household fasteners here as it seems simply bizarre to me, but sometimes there's a good reason for what appears odd at face value.

What seems really crazy about this to me is that if you buy a bolt it's probably BSW and then you buy a spanner and it's A/F which won't fit the stupid bolt. E.g. go to Bunnings and they don't sell bolts that match the imperial spaners they sell. If you look up Whitworth on wikipedia it even cites Australia as a place that still uses it extensively.

Originally Posted by blackfrancis

What seems really crazy about this to me is that if you buy a bolt it's probably BSW and then you buy a spanner and it's A/F which won't fit the stupid bolt. E.g. go to Bunnings and they don't sell bolts that match the imperial spaners they sell. If you look up Whitworth on wikipedia it even cites Australia as a place that still uses it extensively.

That´s a whole new can of worms. Can Wikipedia be truly trusted?

Originally Posted by Pete F

Anyway, I was hoping somebody could explain why whitworth is still used so extensively for household fasteners here as it seems simply bizarre to me, but sometimes there's a good reason for what appears odd at face value.

Maybe its just a case of the tooling for making it hasn't worn out yet. Though I think that probably wouldn't be true after all this time. Speaking of odd ball threads. some time ago I bought a small compressor and a nail gun from Bunnings. Also bought a pack of quick release air couplings. This was a sealed blister pack. Anyway I didn't get around to opening the fittings for a fair while as I decided to use the stuff I already had. When I finally opened the pack I discovered that all the female couplers had BSP threads and all the males had NPT.

bollie7

Originally Posted by blackfrancis

What seems really crazy about this to me is that if you buy a bolt it's probably BSW and then you buy a spanner and it's A/F which won't fit the stupid bolt. E.g. go to Bunnings and they don't sell bolts that match the imperial spaners they sell. If you look up Whitworth on wikipedia it even cites Australia as a place that still uses it extensively.

Gents,
I believe that you may misunderstand the plethora of Imperial measurements found among hardware stock thread offerings is really UNC and UNF, not Whitworth as the Chinese make these for the yanks by the shipload and they are cheap and easy to offload out here in Oz to the hardware chain mobs.

Industrially speaking 98% of the blueprints and drawings I have been involved with in the last 30 years involve Metric threads.

Imperial, in my experience has only been used if the original equipment or machinery involved has been upgraded and requires Imperial threads for the replaced or repaired equipment to match up.

Sure, there were in the past a bit of Sae and Whitworth thread sizes as a legacy from the POM motor vehicles.That may be the origin of the wiki reference.

I still recall seeing this crap in the early Nissan engines as they were exact copies right down to thread specs, thankfully those days have gone.Once you got back to the clutch the bastrds went back to metric.Having to purchase another set of spanners to complete the mechanical work was not amusing.

As for Wikipedia I would take their pronouncements with a grain of salt as it is often unreferenced. You and I are able to write a article and place it there. It won’t necessarily mean it is correct ,its just some ones opinion, as this is.

cheers

Grahame

Originally Posted by Grahame Collins

Gents,
I believe that you may misunderstand the plethora of Imperial measurements found among hardware stock thread offerings is really UNC and UNF, not Whitworth as the Chinese make these for the yanks by the shipload and they are cheap and easy to offload out here in Oz to the hardware chain mobs.

Grahame I may have misunderstood what you were saying here. According to Zenith's own catalogue (and they seem to be the major supplier to the stores I know) most of their fasteners are "whitworth thread" Zenith Home For all their reference to whitworth they sure as heck don't look like rounded threads to me and I can't find my thread thingie (what the heck is that called anyway, brain fart) to measure the angle.

I'm definitely no expert on this, so could be waaaay off the mark here, but my understanding is that while the thread form is different, the pitch is identical in MOST cases for the same diameter bolt (except 1/2"????) and so they can be interchanged. However the loading on the thread is all screwed up so while it may fit it may fail in service under load.

Unfortunately this whole area is a complete shambles from what I can tell. Amongst relatively common nut/bolts there are only 3 systems that I can think of whitworth, metric, and UN. Obviously their derivatives (and clearly other specialist systems), yet I've seen "AF tap sets" advertised. As far as I'm aware "AF" means "across flat" and is a measure of bolt head size, there is no "AF" thread standard and this is actually referring to UNF?

Yes AF means across flat. If you measure the heads on a whitworth bolt they are a different size to the corresponding UNC bolt. You need a whitworth spanner for them, not an AF one, so it's extremely easy to identify a hex-head whitworth bolt from a UNC one. The bolts they usually sell at hardware shops, in my experience, are whitworth not UNC. Even speacilist bolt shops often stock certain whitworth bolts that they don't have in UNC. I've yet to be told we don't have this in whitworth but we have it in UNC, the other way round I've heard alot.

Originally Posted by blackfrancis

If you measure the heads on a whitworth bolt they are a different size to the corresponding UNC bolt. You need a whitworth spanner for them,

nah, you just use a shifter

Yer, they sell them at Bunnings

Originally Posted by Pete F

Grahame I may have misunderstood what you were saying here. According to Zenith's own catalogue (and they seem to be the major supplier to the stores I know) most of their fasteners are "whitworth thread" Zenith Home For all their reference to whitworth they sure as heck don't look like rounded threads to me and I can't find my thread thingie (what the heck is that called anyway, brain fart) to measure the angle.

I'm definitely no expert on this, so could be waaaay off the mark here, but my understanding is that while the thread form is different, the pitch is identical in MOST cases for the same diameter bolt (except 1/2"????) and so they can be interchanged. However the loading on the thread is all screwed up so while it may fit it may fail in service under load.

Unfortunately this whole area is a complete shambles from what I can tell. Amongst relatively common nut/bolts there are only 3 systems that I can think of whitworth, metric, and UN. Obviously their derivatives (and clearly other specialist systems), yet I've seen "AF tap sets" advertised. As far as I'm aware "AF" means "across flat" and is a measure of bolt head size, there is no "AF" thread standard and this is actually referring to UNF?

What does that 2nd paragraph mean,what threads are you reffering to.

Originally Posted by pipeclay

What does that 2nd paragraph mean,what threads are you reffering to.

Sorry I wasn't very clear was I, the tpi is the same between UNC and BSW (and yeah I checked it is 1/2" that's different, no 13 tpi in BSW, guess he was superstitious). However the thread loading is such that if interchanged the thread may fail under load and shouldn't be used. So I guess the warning they're trying to convey is if a hole is tapped for BSW in the lovely Morgan suspension you've been slaving over don't go and jam a UNC bolt in there, even though it may well fit, or the first corner you try in it could be the last
That's my understanding anyway.

Edit: Ok I just tried it for myself. Firstly the Zenith bolts I have here are definitely whitworth, no doubt about it. Yes a UNC nut will fit on a whitworth bolt, but there's no doubt there's something terribly wrong as it feels sloppy. I couldn't get the whitworth nuts on to the UNC bolts however. Finally, I FINALLY figured out was going on with the spanner sizes, the UNC are standard AF spanners, metric are metric spanners, so far so good. The whitworths take metric spanners (though not sure if all sizes) so that would certainly explain why I was scratching my head a few times as to what nut/bolt I was dealing with as it clearly wasn't either metric or UNC. The penny drops ... Pffft, clear as mud to me now!

The TPI is the same between BSW and UNC except as you mentioned 1/2" but in engineering terms I wouldnt use an UNC nut on a BSW thread unless it was the last thing you could do to get you out of trouble,the TPI might almost be the same in all cases but the Thread Angle is different.
Same as you wouldnt for good results use a BSP fitting in NPT unless it was last resort.

Originally Posted by Pete F

Finally, I FINALLY figured out was going on with the spanner sizes, the UNC are standard AF spanners, metric are metric spanners, so far so good. The whitworths take metric spanners (though not sure if all sizes) so that would certainly explain why I was scratching my head a few times as to what nut/bolt I was dealing with as it clearly wasn't either metric or UNC. The penny drops ... Pffft, clear as mud to me now!

Don't get too comfortable there. There is even variation in Whitworth. Not in the actual threads but in the way the head size is measured. There is Whitworth and British Standard Whitworth. I can't remember how it goes now (its 20 years since I worked on anything with whitworth) but for example a spanner marked 1/2" Whit is not the same size as one marked 1/2"BSW.

bollie7

Originally Posted by bollie7

Don't get too comfortable there. There is even variation in Whitworth. Not in the actual threads but in the way the head size is measured. There is Whitworth and British Standard Whitworth. I can't remember how it goes now (its 20 years since I worked on anything with whitworth) but for example a spanner marked 1/2" Whit is not the same size as one marked 1/2"BSW.

bollie7

Ha Ha, oh gawd! It really is out of control isn't it.