Am I a singular Luddite or not?

One thing in Whitworth's favour was standardized bolt hex and nut sizes, what has always tended to rip my nighties is the multifarious hex sizes in metric fasteners. 10mm in particular. I've come across 14, 15, 16 and the ubiquitous

17mm hex all on 10mm fasteners. One thing I have against Whitworth is the size of the hexes as against the Unified series. Unified being smaller makes for tidier and or lighter fasteners, that's the biker in me coming out.:-) As for BSF, it always had the best TPI to Diameter ratio of any fastener series, it's longevity as heavy truck wheel fastener is a good indicator.

As for personal preference, metric supply dictates usage, however I tend toward Unified fasteners (weight & compactness) in my personal projects with the only metric fastener finding real favour with me are SKF locknuts as fitted to taper sleeve bearings.. Cat Unified bolts are a great favourite of mine also because of the strength and variety available.

Tom Who now needs to go and lie down and rest his arm.

Probably not, we use BA and Metric stuff at work, still use Imperial sizes/dimesnions on PCB layouts, engines are BSW/BSF, or even earlier still they are Whitworth.

Anything from the WWII years onwards is likely to have a healthy mixture of all of them!

Peter

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No, you are not on your own - not by a long way.

I have all the threads you can imagine amongst my vehicles (my 1969 Norton uses cycle rate thread on the engine mounting bolts + BSF and BSW). I have lathes going back to 1930, and a 2004 Ducati.

I have a small metric tap and die set, and metric seemed a good way to go when I needed to make a throttle linkage recently (easy to get get bolts and nuts), and I selected some metric bolts from my collection and they are nothing like the ones in my tap & die set.

How many taps and dies do you need to have a comprehensive metric set ?? It seems like hundreds !! There is no point on standardising on an infinite number of variations !

One thing I do have is Whitworth's original proposal for standardising threads. A friend gave me bound copies of the "The Practical Mechanic and Engineers Magazine" from 1942 to 1945ish, and it has Whitworths proposal - and not many people may realise that he didn't calculate it on an engineering basis, he surveyed many engineering works making their own threads and then took an average. He also said that a finer thread would be better for steel (yes Whitworth was suggesting what came to be BSF).

I understand and can cut BSF and Whitworth (and cycle rate) - but BA and especially metric are still a mystery to me. Maybe there is a book somewhere that explains all of the variations on metric, but I can't even sort out the nuts and bolts I have - more and more are going in the unknown jar - and I think they are metric odd-sizes as they are mostly newish in appearance. I also have problems sorting Whitworth from UNC - they are all lumped together (yes I know its a sin - but I can't think of an easy way to separate them) !

The Victorians had it easy !!

Steve

No, you are not on your own - not by a long way.

I have all the threads you can imagine amongst my vehicles (my 1969 Norton uses cycle rate thread on the engine mounting bolts + BSF and BSW). I have lathes going back to 1930, and a 2004 Ducati.

I have a small metric tap and die set, and metric seemed a good way to go when I needed to make a throttle linkage recently (easy to get get bolts and nuts), and I selected some metric bolts from my collection and they are nothing like the ones in my tap & die set.

How many taps and dies do you need to have a comprehensive metric set ?? It seems like hundreds !! There is no point on standardising on an infinite number of variations !

One thing I do have is Whitworth's original proposal for standardising threads. A friend gave me bound copies of the "The Practical Mechanic and Engineers Magazine" from 1942 to 1945ish, and it has Whitworths proposal - and not many people may realise that he didn't calculate it on an engineering basis, he surveyed many engineering works making their own threads and then took an average. He also said that a finer thread would be better for steel (yes Whitworth was suggesting what came to be BSF).

I understand and can cut BSF and Whitworth (and cycle rate) - but BA and especially metric are still a mystery to me. Maybe there is a book somewhere that explains all of the variations on metric, but I can't even sort out the nuts and bolts I have - more and more are going in the unknown jar - and I think they are metric odd-sizes as they are mostly newish in appearance. I also have problems sorting Whitworth from UNC - they are all lumped together (yes I know its a sin - but I can't think of an easy way to separate them) !

The Victorians had it easy !!

Steve

No you are not. I agree, I tend to prefer BSF & BA, though I am not sure why. Certainly when making accessories or 'improvements' for the lathe I would prefer to use imperial, because that is what it was built with. But I do generally use metric bought fasteners now because they are so much cheaper and easier to get hold of. On the other hand, if I have to machine a thread a I use an imperial size because I have an imperial lathe, and Whitworth form chasers. This results in jobs with a rather unfortunate mixture.

Where can I get small quantities of

a) M2.5 socket csk's b) BA and smaller BSF cap heads & socket grub screws

at non-loony prices

and c) metric pitch hand chasers, at all?

Metric has three distinct ranges. Course, Medium and Fine.

Course is more or less the standard which you'll find in most applications. Medium and Fine tend to be used for more specialist applications (typically pipe/brake fittings, i.e.things where using the wrong bolt would not be wise)

For the individual thread diamters/pitches, check out

and have a look at their helical insert listings.

It all makes perfect sense to designers. On mass produced items, the hex size is used to determine the torque of any given bolt. Typical examples being 8mm bolts, where a 10mm head is generally used on items that only have to be nipped up (would have a torque in the region of

20Nm), whereas as a 13mm head (the standard sized head), would go a bit tighter (think it's somewhere in the region of 30Nm). This means on production lines, torque wrenches/air guns can be set up with a set sized socket, and the assembly workers know that if the socket fits, it'll be at the right torque. Quite an ingenious idea when you think about it, but a total PITA when you have to dismantle it though. And it's also why components with critical tightening torques tend to have odd ball sized hexs, or use Torx heads.

"Moray Cuthill

Hardly..

10mm hex on a 8mm bolt? I don't think so, 6mm bolt more like.

As for 8mm fasteners, 12mm hex is more accepted than 13mm.

Tom.

Tom:

M8 comes with 13mm A/F head as standard over here, perhaps NZ is different?

Most of our local fastener shop stocks come from Europe, we buy stainless nearly all the time and that seems to be sourced in Italy, but wherever they come from, M8 is always 13mm A/F.

Cars/vans seem to use the M8 12mm A/F, seem to remember the last van or two had them.

Peter

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Isn't he dead already?

Nick, metric

13mm is the standard. The 17mm noted somewhere else is replaced by 16mm.

Nick

May I suggest that the automotive industry is the biggest user of metric bolts and as such, setter of standards that others, belatedly follow? A former setter of such standards was the SAE Handbook of multifarious editions..

Tom

Not by the world's biggest car manufacturer..

Tom

Does the Robin have metric nails er .. bolts?

Nick

Not true in Europe, the ISO standard sets what 'should' be used, but in practice as in other industries the largest users tend to have their own standards. The Japanese were the first to drift on hex head sizes, quickly followed by almost everyone else.

We would probably have some difficulty in getting 12mm A/F M8 bolts, especially on a Sunday! :-))

I'll ask our local guys Tuesday, I'm off up north tomorrow.

Peter

-- Peter & Rita Forbes Email: snipped-for-privacy@easynet.co.uk Web:

Says something about you, Nick, when you associate a Robin as being a car..

Tom

As I was saying? :-)

Suppliers are a trifle more obliging downunder. :-) I've just remembered I had a new box of M8 x 16 set screws in the wagon. 500, all 8.8 grade 12mm across the flats..

Tom

Most body fittings on european fords use that size of bolt, that's why I picked it. For it's application, a 6mm bolt would work, but given a little bit rust it would most likely snap, or on certain applications, may even fail in use. So the designers choose the next standard thread size up, and spec a smaller head size so it still gets torqued to the same tightness as a 6mm bolt. It's going back to the classic statement that a bolt sould be as tight as the avergae man can tighten said bolt with a standard length spanner.

It all comes down to the car manufacturer's cost cutting. It's cheaper to have bolts made with a smaller head, than it is have them made with the standard sized head. Given the the millions of bolts that car manufacturers use, if they can save a fraction of a penny on each bolt, it soon mounts up to quite a saving, and it also saves a little bit weight. And as Peter has said, 13mm is the standard AF size for a 8mm bolt in europe. It's only car manufacturers that tend to stray from the standard head sizes for the cost reasons above.

What you're talking about are not bolts per se but rather flanged body set screws. there's no way you could use a 10mm hex on a conventional M8 bolt.

So the norm is? Like I said, 12mm hex on M10 bolts.

Guess who uses the most bolts in industry?