Why is the world of model engineering still imperial?

[SillyOldDufferModerator @sillyoldduffer]

Posted by Paul McDonough on 07/03/2023 08:56:07:

"Really this thread is going nowhere"

I'm sorry i asked! :0(

Not at all, it's a complicated subject deserving attention, even if we have our ideas rejected!

Standardisation of Weights & Measures has a long and difficult history. A story of order versus chaos, conservatism vs progress, practical vs theory, me vs us, local vs national, and national vs international. And a potent symbol of who is in power, which is why ambitious politicians fostered the impression that Metric was foisted on Brits by the EU. A fib.

It was recognised early that different measurement systems are an obstacle to trade. In medieval times ordering a 'yard' of cloth caused short-changing or over-provision because the suppliers yard was different. The differences were exploited ruthlessly by dishonest traders.

Imperial is the result of many painful rationalisations over centuries. They often had to be enforced by the King sending the boys round to 'explain' the need for change, and the conversation often ended in violence.

A tailor trading in Truro sees no advantage in dumping great-grandad's yard, which works perfectly well for him, and he's not going to cooperate just because the whole country poorer as a result as a result of trade problems. Not a problem in Truro that Baltic merchants can't trust English cloth measure, so our tailor resists. He calls on tradition, politics, propaganda, and deploys fear, uncertainty and doubt to delay and prevent change. His motives are personal and local, and ignore wider benefits that don't apply directly to him.

Imperial as we know it is a product of 19th Century efforts to deal with the Industrial Revolution struggling due to duff weights and measure. To reduce bother, they built on traditional foundations. The root was the yard, pound, and second, heavily embellished with hundreds of size units, related by odd ratios determined in the past. So we have grains, drams, ounces, pounds, stone, hundredweights, and tons, and the ratios are inconsistent, so although a dram is 1/16th of an ounce, there are 27.34375 grains in a dram. There are 16 ounces in a pound, 14lbs in a stone, 7.142857 stones in a Hundredweight, and 20cwt in a ton. Length measure also has many multi-ratio relationships.

Fairly obviously I hope, these conversions complicate Imperial calculations. Just because the resulting confusion may not apply to us individually (in our local home workshop), does not mean everyone is well-served by Imperial – far from it.

The big trouble with Imperial starts when derived units are needed. In mechanics these are: Energy, Force, Frequency, Power, and Pressure. Although man-in-shed engineering rarely calculates in them, they are fundamentally important to anything other than basic engineering design. Inches and thou are fine when building a steam locomotive to a plan, because deciding how strong the boiler needs to be to operate safely at a given pressure was done by someone else, a mathematically trained engineer. I worry about him because although the maths can be done in Imperial measure, it's hard work. Imperial measure is a poor tool for advanced work in science and engineering. It's odd that some model engineers deliberately favour a poor tool!

Whilst Victorian legislators were corralling Britain's chaotic traditional measures into Imperial for commercial reasons, the scientists had gone a step further. They had realised a century before that it was feasible to design a coherent system of weight and measures. (Mostly coherent – it can't be perfect.) That is, a system where units are logically related, and there are no random ratios between them. The system supports domestic needs whilst greatly simplifying difficult calculations. Not a cosy change; a coherent system requires most historic measures to be abandoned, and this trampled on the delicate feelings of traditionalists and everyone who had painfully learned to calculate in Imperial! Old dogs don't like learning new tricks. So there was an immediate, powerful reaction against metric, derided as 'foreign' by British vested interests, even though British brains were in the forefront of the new system.

Personally, I think it's a mistake to mix politics, emotion, tradition with engineering and science. When a better tool becomes available, engineers should use it. Essential in brutally competitive manufacturing. Chaps who held the firm back by insisting on Whitworth, Imperial measure, old-fashioned methods, and Spanish practices, thought small-c conservatism made their lives easier: actually, it was one of the reasons that so many 'solid' British engineering companies went to the wall.

Lesson learned – don't lumber future engineers with inferior methods just because they happen to suit me.

In my humble opinion, Imperial has been a dead-weight for well over a century. Like smoking tobacco, people love it, but the habit is harmful. So, are you a Truro Tailor or a thrusting industrialist planning for 2030 and beyond? Does anyone really believe Imperial measure will be an asset to British engineering when we are all dead?

Dave

[JasonBModerator @jasonb]

So why are they not called Massing Scales or are there a few here who call them that rather than weighing scales and I bet you all weigh in your scrap metal.

No "M" on the weights from my balance scale either

[Martin KyteParticipant @martinkyte99762]

It’s not what it’s called it’s what it DO.

I did say I was splitting hairs but such is subtlety.

regards Martin

[Harry WilkesParticipant @harrywilkes58467]

Posted by SillyOldDuffer on 07/03/2023 12:07:51:

Posted by Paul McDonough on 07/03/2023 08:56:07:

"Really this thread is going nowhere"

I'm sorry i asked! :0(

Not at all, it's a complicated subject deserving attention, even if we have our ideas rejected!

Standardisation of Weights & Measures has a long and difficult history. A story of order versus chaos, conservatism vs progress, practical vs theory, me vs us, local vs national, and national vs international. And a potent symbol of who is in power, which is why ambitious politicians fostered the impression that Metric was foisted on Brits by the EU. A fib.

It was recognised early that different measurement systems are an obstacle to trade. In medieval times ordering a 'yard' of cloth caused short-changing or over-provision because the suppliers yard was different. The differences were exploited ruthlessly by dishonest traders.

Imperial is the result of many painful rationalisations over centuries. They often had to be enforced by the King sending the boys round to 'explain' the need for change, and the conversation often ended in violence.

A tailor trading in Truro sees no advantage in dumping great-grandad's yard, which works perfectly well for him, and he's not going to cooperate just because the whole country poorer as a result as a result of trade problems. Not a problem in Truro that Baltic merchants can't trust English cloth measure, so our tailor resists. He calls on tradition, politics, propaganda, and deploys fear, uncertainty and doubt to delay and prevent change. His motives are personal and local, and ignore wider benefits that don't apply directly to him.

Imperial as we know it is a product of 19th Century efforts to deal with the Industrial Revolution struggling due to duff weights and measure. To reduce bother, they built on traditional foundations. The root was the yard, pound, and second, heavily embellished with hundreds of size units, related by odd ratios determined in the past. So we have grains, drams, ounces, pounds, stone, hundredweights, and tons, and the ratios are inconsistent, so although a dram is 1/16th of an ounce, there are 27.34375 grains in a dram. There are 16 ounces in a pound, 14lbs in a stone, 7.142857 stones in a Hundredweight, and 20cwt in a ton. Length measure also has many multi-ratio relationships.

Fairly obviously I hope, these conversions complicate Imperial calculations. Just because the resulting confusion may not apply to us individually (in our local home workshop), does not mean everyone is well-served by Imperial – far from it.

The big trouble with Imperial starts when derived units are needed. In mechanics these are: Energy, Force, Frequency, Power, and Pressure. Although man-in-shed engineering rarely calculates in them, they are fundamentally important to anything other than basic engineering design. Inches and thou are fine when building a steam locomotive to a plan, because deciding how strong the boiler needs to be to operate safely at a given pressure was done by someone else, a mathematically trained engineer. I worry about him because although the maths can be done in Imperial measure, it's hard work. Imperial measure is a poor tool for advanced work in science and engineering. It's odd that some model engineers deliberately favour a poor tool!

Whilst Victorian legislators were corralling Britain's chaotic traditional measures into Imperial for commercial reasons, the scientists had gone a step further. They had realised a century before that it was feasible to design a coherent system of weight and measures. (Mostly coherent – it can't be perfect.) That is, a system where units are logically related, and there are no random ratios between them. The system supports domestic needs whilst greatly simplifying difficult calculations. Not a cosy change; a coherent system requires most historic measures to be abandoned, and this trampled on the delicate feelings of traditionalists and everyone who had painfully learned to calculate in Imperial! Old dogs don't like learning new tricks. So there was an immediate, powerful reaction against metric, derided as 'foreign' by British vested interests, even though British brains were in the forefront of the new system.

Personally, I think it's a mistake to mix politics, emotion, tradition with engineering and science. When a better tool becomes available, engineers should use it. Essential in brutally competitive manufacturing. Chaps who held the firm back by insisting on Whitworth, Imperial measure, old-fashioned methods, and Spanish practices, thought small-c conservatism made their lives easier: actually, it was one of the reasons that so many 'solid' British engineering companies went to the wall.

Lesson learned – don't lumber future engineers with inferior methods just because they happen to suit me.

In my humble opinion, Imperial has been a dead-weight for well over a century. Like smoking tobacco, people love it, but the habit is harmful. So, are you a Truro Tailor or a thrusting industrialist planning for 2030 and beyond? Does anyone really believe Imperial measure will be an asset to British engineering when we are all dead?

Dave

🥱

[Paul McDonoughParticipant @paulmcdonough43628]

"you have to remember that it is cold in the workshop at the moment and all the members are sat in front of the fire with nothing better to do."

True, me included I'm really excited to get started but its been below 5 deg C out there its all i can do to stare at it and oil the bed etc.

"Model engineering is imperial because 99% of drawings are done in imperial, we all bought mics verniers etc years ago when they were imperial,"

Also largely true, but for people like me not so, I've just bought a new micrometer and DTI, kit I could not have dreamed of owning when i was last machining stuff over 40 years ago on my old mans lathe at my parents home, thankfully being mostly digital it can do both, although i do have a traditional 'one trick pony' digital micrometer as well!

[Jonathon MCParticipant @jonathonmc86670]

Because my Grandfathers stuff I inherited in 1969are still used and very useful. 😄😁

[File HandleParticipant @filehandle]

Posted by Martin Kyte on 07/03/2023 12:03:04:

My point about spring balances and scales that rely on spring extension is that they rely on 2 readings. One with a known mass to calibrate the spring extension and a second with an unknown mass to make the comparison. The equations are the same as the balance beam and providing the device is in the same location as it was calibrated everything cancels except mass and length. Therefor they are mass comparators irrespective of what units you paint on the scale or the standard mass. Of course once you know the mass the weight under the same gravity is in the same ratio.

I know I’m splitting hairs but that’s where this discussion has gone. If there is no gravity term in the equations then you aren’t measuring weight.

regards Martin

Of course you are because you are measuring a force due to gravity. Remove the gravity and the device doesn't work.

[derek hall 1Participant @derekhall1]

To answer the thread question, my answer is that perhaps many of the popular designs are still in Imperial.

I work in both, metric mill, imperial lathe. My apprenticeship was generally also a mixture of both, I convert using a calculator, not having a DRO.

One thing I always have an issue with is that new people coming into this "hobby" need to realise that there are critical dimensions in some components and less critical dimensions in others. Many waste time in ensuring, for example, that the base plate of a model engine has to be exactly the dimension on the drawing….it could be 1/8inch longer or 3.175 mm and no one would notice !

The elephant in the room though is getting new blood into our hobby, I am sure many are put off by imperial measurements. I guess as us old duffers eventually keel over with our hands around a 0 to 1 inch imperial micrometer, imperial units in model engineering like us will eventually wither and die…

The important thing is to get in the workshop and make stuff, either in metric or imperial, who cares !

Regards to all

Derek

[Nigel Graham 2Participant @nigelgraham2]

I think the Imperial plans sets are going to be around long after any of us has been "re-allocated" to the next world with our favourite six-inch by sixty-fourths rule in our boiler-suit pocket.

Yet with CAD now, how feasible would it be for the publishers to scan those drawings and re-dimension them to mm? And while at it, verifying the drawing's fitting accuracy?

If so it ought also be possible to tidy them into rational sets with a lot of the details parts on A4 sheets, rather than the haphazard all-on-one typical of so many? It was done to reduce the amount of big sheets of paper needed but would the economics now favour such revision?

One possible route there is to sell the prints that need be big (the GA, and large components) but offer the smaller A4 sheet drawings on-line for the buyer to print at home. (A3 too though fewer home users are likely to have A3 printers.)

 

I don't know – I cannot do it but that does not mean it cannot be done! I can't swim either, but many do.

'

I don't know if some newcomers are put off by Imperial measures they have not been taught. Yet neither do most of them know a headstock from a tailstock or Walschaert's from Stephenson's, till they start to learn their way around it.

I think more importantly is if they have grasped any appreciation of actually making something rather than just buying it. Though that will go against realising the baseplate can be three-and-a-bit mm overlong but the cylinder and piston must match.. Treads carefully, lest one awakes Fafnir the Dragon, Guardian of the Accursed Ring… Gauge.

I recall some ten years ago a man gazing at my society's club locomotive, a Ken Swan version of the Kerr Stuart 'Wren', in steam at a public event. He was impressed, and asked about availability of parts and "spares" – perhaps thinking it preserved but factory-built. I replied that apart from a few fittings we'd have to make them. just as our club had built the whole engine in the last several years. I think he did believe me, but found the concept very hard to grasp!

I fear more the effect of rush on patience. Everything it seems, must be quick, instant, available with minimum physical and mental effort. Send a txt msg – moan if no immediate reply. Buy a radio-controlled model lorry, say, on-line and you don't even need leave home to collect it almost ready to run. Build the same model from scratch… that is hours of work even if substantially quicker than a similarly-sized miniature steam locomotive – and it needs practical skills and appropriate tools, albeit fewer and simpler than the loco calls for. Is commitment to any leisure pursuit now becoming a rarity?

.

There are optimistic signs, but we of the Sage Age must realise that model-engineering is model-engineering and the youngsters coming along will know engineering in mm and Newtons rather than inches and foot-pounds. So it is for us to encourage them in their way into engineering, before we are sent to measure Infinity with our six-inch rules.

Maybe they can teach some of us a thing or two about modern engineering!

Edited By Nigel Graham 2 on 07/03/2023 22:05:17

[Martin KyteParticipant @martinkyte99762]

Posted by Keith Wyles on 07/03/2023 18:30:42:

Posted by Martin Kyte on 07/03/2023 12:03:04:

My point about spring balances and scales that rely on spring extension is that they rely on 2 readings. One with a known mass to calibrate the spring extension and a second with an unknown mass to make the comparison. The equations are the same as the balance beam and providing the device is in the same location as it was calibrated everything cancels except mass and length. Therefor they are mass comparators irrespective of what units you paint on the scale or the standard mass. Of course once you know the mass the weight under the same gravity is in the same ratio.

I know I’m splitting hairs but that’s where this discussion has gone. If there is no gravity term in the equations then you aren’t measuring weight.

regards Martin

Of course you are because you are measuring a force due to gravity. Remove the gravity and the device doesn't work.

That’s not really valid as my reason for posting was the contention that the general public don’t measure mass as it is difficult. In the absence of gravity constant acceleration will do just as well. Just not for Joe Public.

regards Martin

[duncan webster 1Participant @duncanwebster1]

Posted by Keith Wyles on 07/03/2023 18:30:42:

Posted by Martin Kyte on 07/03/2023 12:03

Of course you are because you are measuring a force due to gravity. Remove the gravity and the device doesn't work.

A mass balance will work just fine in reduced gravity, a spring balance won't. Neither will work in zero gravity.

[samuel heywoodParticipant @samuelheywood23031]

One thing i hope we can all agree on is on the matter of fixings…… ( ducks for cover)

Imperial fixings are way over complicated~ how many thread standards?

Metric is sooo much simpler, i don't even have to consult a chart for the right tapping drill.

If you are of a certain age your grandfather / father (in those days of thrift) used to keep a tin of 'saved' nuts & bolts in the shed/garage. All mingled in together, dunno why they never sorted them.

When a project / job came up out would come the tin~ emptied onto a newspaper & sorted through until the right fixing for the job was found.

How many wasted hours sorting through all those different imperial fixings i wonder?

Well i;ve still got a 'tin' but it's childs play with metric.

[JasonBModerator @jasonb]

Until you throw a few Metric fine nuts into the box and why not a few constant pitch ones as well so that M10 nut although the same thread form could easily have 4 different pitches.

For example I've used the usual metric coarse M6x1 for fixings on a model, the finer M6x0.75 where I wanted a finer thread and M6x0.5 on pipework due to the thin wall.

[File HandleParticipant @filehandle]

Posted by JasonB on 08/03/2023 07:23:59:

Until you throw a few Metric fine nuts into the box and why not a few constant pitch ones as well so that M10 nut although the same thread form could easily have 4 different pitches.

For example I've used the usual metric coarse M6x1 for fixings on a model, the finer M6x0.75 where I wanted a finer thread and M6x0.5 on pipework due to the thin wall.

Jason beat me to it.

[HOWARDTParticipant @howardt]

Isn’t the simple answer the drawings were created in the imperial age and being copyright they cannot be metricated. I assume most of the original designers are long gone, of not all. Modern day designers would I expect, at least in Europe and Australasia, create them in metric. Most Americans I think use imperial thought industry is shifting to the metric system. If you want to see more metric then create some new designs.

[Martin KyteParticipant @martinkyte99762]

Posted by HOWARDT on 08/03/2023 08:28:00:

Isn’t the simple answer the drawings were created in the imperial age and being copyright they cannot be metricated. I assume most of the original designers are long gone, of not all. Modern day designers would I expect, at least in Europe and Australasia, create them in metric. Most Americans I think use imperial thought industry is shifting to the metric system. If you want to see more metric then create some new designs.

Absolutely, I said that about a hundred posts ago. Further more who would do the conversions, certainly not our suppliers. Boilers may be considered as new designs so could have to be reassessed etc. There is a considerable amount of inertia in the system.

regards Martin

[CirclipParticipant @circlip]

ALL drawings can be "Metricated" but it's too expensive to change every design, just in case the one YOU want is available. As stated in post # – (OH, we STILL have the inability to refer to post numbers, despite THAT subject re occurring with the same monotonous regularity) the inability of some to determine which dimensions NEED to be direct conversions to metric, don't try to throw it over to today's "Universal" draughtsmen who prepare offerings via a graphics programme for magazine publication.. Even back in Percival Marshall's day when the Draughties KNEW what steam engineering was all about, could get sizes wrong.

Simple question for the CAD brigade who think pressing the 'Convert' button on a loaded Imperial drawing is the easy answer, 1/8" – 0.312" converts to 7.9248mm and before you jump in and state "That's 8mm," NOT if it's tied to part of a chain dimension – Cylinder position etc. on a steam loco. Should we change to 88.9mm gauge?

Regards Ian.

[Michael GilliganParticipant @michaelgilligan61133]

[ deleted ]

Edited By Michael Gilligan on 08/03/2023 10:36:50

[JasonBModerator @jasonb]

As one of the CAD brigade I can assure Circlip that all my conversions are full metric conversions not just mathmatical ones as I have said a few times in this thread already.

Oh and in my book and on my screen 1/8" is not 0.312" or 7.9248 neither is 1/8" minus 0.312" depending on what you intended to write

As to the comment a bit earlier about the base of an engine not needing to be anything critical yes that is quite OK provided care is taken as to where subsequent dimensions are taken from, a lot of drawings will use all 4 sides as well as ctr lines to place various features.

Now what about published drawings, I think the last ones Myhobbystore made available were the Nemett Lynx (metric) about 12years ago, last loco or stationary engine qite some time before that and I doubt we will see any more being sold as they once were. At best you will get whatever is submitted to ME or EiM and have to get back issues to see the newer designs and apart from any errors picked up during the series unlikely to ever be revised.

[SillyOldDufferModerator @sillyoldduffer]

Posted by HOWARDT on 08/03/2023 08:28:00:

Isn’t the simple answer the drawings were created in the imperial age and being copyright they cannot be metricated. …

I don't see much merit in metricating existing plans unless there's solid advantage in doing so. Such as selling them to newcomers with metric workshops, nothing but metric stock sizes, who have no background knowledge of Imperial or English measure. The amount of unnecessary conversion baked into Imperial is one of it's chief evils, and converting again just to be in metric is evil too. Metrication's advantages apply mostly to new design, not slavishly redimensioning old plans.

This thread's title is 'Why is the world of model engineering still imperial?' That's debatable! True modelling is popular in the UK, but surely unjustified to assume there are more British modellers than the rest of the world combined? Dare I cause further upset by suggesting it's likely more model engineers work in metric than Imperial? Not in your local club maybe, but remember that's a tiny sample. Be interesting to know how many mini-lathes are sold worldwide each year, and what proportion of them are Imperial rather than Metric. Even though I expect Imperial machines predominate in the US, is anyone prepared to bet the farm on Imperial being the winner?

Looking to the future, has it occurred to anyone else that loyally sticking to traditional British measure is a good way of ensuring that British model-engineering will die abroad, and probably here too in the long run? Very few countries know much about Imperial, and the little English boys next door to me aren't taught it at school either. My generation was probably one of the last to cover imperial in depth, and I had to learn Metric too. Being taught both in parallel gave me a very clear understanding into which of the two performed best in the large.

Strange that so many enthuse about Imperial measure without insisting we go back to £sd, a monetary system with many of the same advantages; 240d = £1, 12d = 1s, 20s = £1, 2/6 = £⅛ etc. I think £sd passed relatively painlessly into history because most people had been hurt by the way it makes sums unnecessarily hard, whilst the simple advantages of 100p = £1 were instantly obvious. Doubly so when everyone could own a calculator!

Dave

[JAParticipant @ja]

After five days we have returned to the question and probably the same answers.

Model engineering will truely go metric when there is the demand. The majority of us are boring old farts (excuse me) who can handle Imperial and SI units and even worse argue about their merits. The younger generation have, in general, little knowledge of Imperial units and don't want to know. The change will come during their time and it will be slow since the hobby is, at present, moribund (and not just because it is snowing). How the change takes place and managed is outside our influence, fortunately.

JA

[JasonBModerator @jasonb]

Not sure why being a BOF should stop people designing in metric, take the likes of Anthony Mount most of his later designs were all metric, earlier ones dual and he is getting on, the grasshopper currently in ME is also metric and from his photo I would not say Martin is in the flush of youth.

Luckily we do have the likes of Luker who has given us some metric design locos and also bucked the "it must be copper" trend too so as said change is coming but maybe not that fast.

And yes I did get a bit done in the workshop this morning, making an engine that came out in 1924 but my fully metric design. 2" 50mm of snow won't stop me.

[JellyParticipant @jelly]

Posted by JA on 08/03/2023 11:49:20:

The younger generation have, in general, little knowledge of Imperial units and don't want to know.

I'm not sure this is true, at least in Britain it's still pretty common for young people (who do anything remotely practical at all) to have good familiarity with both imperial and metric systems, and to be able to convert between the two freely.

Most of us* prefer metric, but as long as America exists we have to be conversant in both and the US influence on young people has if anything grown as a result of the internet making "the pond" a lot smaller in people's digital lives.

​

When you get to young people who are being trained in engineering occupations, unit conversions are still considered a fundamental skill they love to drop into the curriculum to catch people out at every level right up to people doing MSc/MEng… At least for people in the process industries.

Because in real life you have to work with systems that were designed anywhere from 1840 to the present day, and built all over the world.

So you may well find yourself having to modify or integrate with an assembly originally built when your grandfather was your age, which now has different components specified by long since defunct OEM's in SI, CGS, US Customary, Imperial, and drawn to three or four different standards.

​

That latter point is why I don't get why metrication of the hobby really matters… In real life the existence (and continued promulgation by Americans) of the imperial system is just something you deal with.

*Yes, I'm claiming to be a young person, but being early 30's that statement is somewhat relative.

Edited By Jelly on 08/03/2023 12:36:01

[Clive SteerParticipant @clivesteer55943]

I think modelling will remain largely Imperial for some yet not just because the drawings are Imperial but because of legacy tooling that often gets passed on to newbies as well as part completed models. Since modelling is rarely profit making using what is easily and cheaply available is prudent. The more likely scenario will be the gradual introduction of metric parts such as fasteners and gears etc. One may build a model to Imperial measurements but substitute commercial of the shelf metric screws rather spend time finding a source of ME screws.

In fact someone starting out in the hobby may find the complexity of different measurement systems and component availability a serious negative and find something easier to do.

CS

[derek hall 1Participant @derekhall1]

A branch off this thread would be "the future of model engineering?"

Both my sons in law (in their early30's) have no idea about "practical" stuff let alone have engineering skills or the pro's and cons of metric or imperial measurement.

Houses are getting more expensive for the younger generation and those that have a garage or even a garden big enough to put a shed in suitable for a workshop are at a premium. If you live in rented accommodation then its even harder to create a workshop. Not even factoring in the cost of machine and hand tools against the cost of living and bringing up a young family for example.

I do not want to change the direction of this thread but I think there maybe a part of imperial measurements that may turn off budding model engineers (young and old).

The days of coming home from work having your tea and going out to the "shed" to bash some metal have changed dramatically.

But the world of Model Engineering is slowly, albeit very slowly turning metric thanks to new published designs (thanks to Jason and others!) – I think this makes the design more accessible and understandable to the metric only generation……and they are the future model engineers

[Author]

Posts