Digital readings

[JohnFParticipant @johnf59703]

Posted by Steviegtr on 22/10/2020 11:50:33:

Yes that was why i posted , Too many 0000 etc. Scrambles my brain. Stupid thing is. I have spent my working life creating & reading drawings in both decimal & imperial. This is the instrument in question . Both imp & metric of the same value.

Steve.

The bottom one I can visualise the size, the top only after a mental calculation to approximate an imperial size ! I do use the metric system for some carpentry — why? well my saw bench has a metric scale so its easier to use millimetres ! For all, well 99% of engineering I use imperial because thats what I was brought up with and all my tools many from apprentice days are imperial, same with all my machines except one lathe.

I used to import a fair amount of product from Italy and of course it was all metric, often we would be discussing size, tolerance etc — metric tolerance in microns, very confusing to me so asked them to send me a list of the terms used thus with a quick 0.03937 calculation to convert.

Metric Micron 0.001mm

0.001

1 millimetre = 0.03937"

0.1 decimo = 0.00397"

0.01 centesimo = 0.00039"

0.001 micron = 0.000039"

I found this useful, 1mm is fairly easy at 40 thou but when it get down to 1/100 or 1/1000 it is not easy to visualise.

[IanTParticipant @iant]

Stevie – just remember that 1mm is about 40 thou – so 0.1 mm is about 4 thou and 0.01 mm is about 0.4 thou – always in a ratio of 1 to 40 (near enough for most things).

If you ever get a bit confused (and sometimes I have to write things down just to make sure they 'look right' ) – then just write " 001.0 mm" and " 0040.0 thou " down, then as you move the decimal point left (or right) just be sure to move it the same amount for both numbers.

0.06mm is six times 0.01mm, so it is also therefore six times 0.4 thou – so it's about 2.4 thou….

(I've just checked and it's really 2.36 thou but you will have to forgive me the difference! )

Regards,

IanT

Edited By IanT on 22/10/2020 15:48:13

[SteviegtrParticipant @steviegtr]

Posted by IanT on 22/10/2020 15:47:11:

Stevie – just remember that 1mm is about 40 thou – so 0.1 mm is about 4 thou and 0.01 mm is about 0.4 thou – always in a ratio of 1 to 40 (near enough for most things).

If you ever get a bit confused (and sometimes I have to write things down just to make sure they 'look right' ) – then just write " 001.0 mm" and " 0040.0 thou " down, then as you move the decimal point left (or right) just be sure to move it the same amount for both numbers.

0.06mm is six times 0.01mm, so it is also therefore six times 0.4 thou – so it's about 2.4 thou….

(I've just checked and it's really 2.36 thou but you will have to forgive me the difference! )

Regards,

IanT

Edited By IanT on 22/10/2020 15:48:13

Thanks for that. Noted.

Steve.

[Nick WheelerParticipant @nickwheeler]

Yes, that's much easier than training your brain to be equally accurate in both 'systems'**

** well, one of them is a system, the other is a mess.

[Chris Evans 6Participant @chrisevans6]

I use mainly imperial sizes on my old motorcycles but all my machinery is metric. I have both metric and imperial measuring tools but really do prefer to use an imperial depth micrometer.

[Dave HalfordParticipant @davehalford22513]

Posted by Steviegtr on 22/10/2020 15:00:03:

Well with all these interesting comments. I understand what most are saying. Back when messing with the motorbikes, we would literally be able to look at a spark plug or the ignition points & have a pretty good idea of the gap in thou's.

I know when i am doing joinery work i stick to metric.

Yes i am the same as many by having a sense of a thou. If it is say 0.06mm then it's over to the wall chart to compare with imperial.

Steve.

Lucas distributors were 15 thou, which happened to be the thickness of a fag packet, simples.

DIY likewise metric.

And yes when someone starts ranting about his mill not being any good because it's 0.05mm out I haven't a clue either.

[old martParticipant @oldmart]

I sometimes get to make stuff to a drawing supplied by one of the other museum volunteers. Metric or imperial, I don't mind which, but fractions are a pain, having to be turned into a usable form.

[peak4Participant @peak4]

I think I've posted this link on here before, but still worth a read.

Barleycorns anyone.

http://metricationmatters.com/docs/WhichInch.pdf

Bill

[Tim HammondParticipant @timhammond72264]

Having watched many, many engineering videos on YouTube uploaded by American machinists like, for example, Joe Pie, Adam Booth or Keith Fenner, I've noticed that they almost always quote dimensions in thousandths of an inch, so 5/8" = 0.625 or 625 thousandths, so if they want to reduce something to, say, 1/2", they know they have to remove 125 thousandths. The clever bit is converting fractions to decimals; I have to consult a Zeus book to know that 29/64 is 0.453" whereas they just know it. I suppose working with these numbers all day every day they just commit them to memory. However I use the technique for Metric – !mm = 1,000 microns, so for example, if I need to reduce a diameter of 22mm to 21,3 mm, 700 microns needs to come off, 350 microns of radius which is equal to 14 graduations on the cross-slide dial. (one graduation = 0,025 mm, 25 microns). Works for me.

[Nigel Graham 2Participant @nigelgraham2]

I suppose the centimetre is taught as something a bit easier to visualise than the millimetre, and frankly the cm is a bit more useful than the mm for everyday use like clothes sizes and household DIY – but the ISO seems to have become dominated by the ivory-towered who don't think beyond arithmetical nicety.

Everyday use is why units like the inch evolved – they may be eccentric and mathematically incoherent but were based on real people using tools, goods, buildings, clothes etc made to suit human sizes; rather than quantum physics and abstract sums.

We of course know the millimetre as between the diameters of a No.60 and 61 drill….

'

Brought up on Imperial and £.s.d. (and vaguely recalling the principles of Compound Multiplication thereof); working in various engineering and science related trades including having to understand logarithmic units, and with a workshop of machines with thous on them…., I can work in either but find some SI units rather baffling.

I know the Newton is a unit of force but can't disentangle the sense from measurements like 70 N/cm, as labelled on a small motor and worm-gear unit here on my computer desk – I have no idea if I can use this motor for the basis of a milling-machine power-feed because I cannot "picture" 70N/cm.

I recall a college lecturer saying 1N is roughly the weight of 4 apples….

As for the cm…. Yes, the rag-trade and some teachers like it, but I recall a Design & Technology teacher telling me of his frustrating at having to teach his pupils mm because his colleagues who should teach it, won't. I stumble with the centimetre, and often find myself mentally converting it to mm. So if someone tells me something is, "about 15cm by 20cm", I think, "Eh? Oh, 150mm by 200mm. About six inches by eight!"

I have been building a hefty timber bench; and found myself working in both inches and mm, but my 4"-scale steam-wagon's prototype was made to feet and inches and so is the model. Though it seems unsure whether it wants BSF/BSW fasteners or M-series – and of course BA is a metric range!

'

If you really want an utter tangle of ISO-approved units, try this, a real example. The value is negative so the hyphen is a minus sign, but at least it does not expand the Pascal to its kg & m components:

-211.5 decibels referred to 1Volt per micro-Pascal,

…. but it's all right because we can abbreviate it, to -211.5 dB re 1Volt per µPa….

… and be glad the powers-that-be graciously allow us to measure our boilers in Bar.litre not Pa.litre, even if we tend to go and write it as Bar/litre – a division!

(1 Bar = 100 000Pa = 100 000 000 000µPa. At best our ears can or could just detect a sound pressure-level of only 20 – twenty – of those teeny-weeny micro-Pascals).

[SteviegtrParticipant @steviegtr]

Posted by Dave Halford on 22/10/2020 18:02:45:

Posted by Steviegtr on 22/10/2020 15:00:03:

Well with all these interesting comments. I understand what most are saying. Back when messing with the motorbikes, we would literally be able to look at a spark plug or the ignition points & have a pretty good idea of the gap in thou's.

I know when i am doing joinery work i stick to metric.

Yes i am the same as many by having a sense of a thou. If it is say 0.06mm then it's over to the wall chart to compare with imperial.

Steve.

Lucas distributors were 15 thou, which happened to be the thickness of a fag packet, simples.

DIY likewise metric.

And yes when someone starts ranting about his mill not being any good because it's 0.05mm out I haven't a clue either.

Yes i always remember mum's 3 year old Viva HA 1964. was 15thou points but i always got better result/ performance when narrowed to 12 thou. Or just a bit more than the Embassy No6 packet. It took me a while to work out that. ( by the way most of my working out is done while laid in bed or sat on the royal throne) Please delete any images.

So mum's Viva. The distributor centre bushing was worn badly. I worked this out because mum said, whenever i go up a hill the car runs terrible, but on the flat it goes great. Also the acceleration is poor. Of course the vacuum advance pulls the points base plate around when going up a hill & accelerating. Causing the base plate to move & alter the points gap. Nothing to do with the thread but i always seem to digress. Sorry. Oh my god i was 15 then. Where have all the years gone.

Steve.

[duncan webster 1Participant @duncanwebster1]

Imperial is only more intuitive if that's what you're used to. Try explaining it to a French or German engineer. Anyone who has done engineering sums involving more than just adding lengths together will surely acknowledge that the consistent units of SI are a lot easier than Imperial with its miriad of conversion factors. Imperial will die out soon whatever the greybeards say, my son designs pharmaceutical robotics, and just doesn't understand inches etc.

SOD tells us that work is mass * distance, no it's not, it's force * distance, and Nigel has a gearbox rated in N/cm, which is nonsense, should be Newtons * cm. Actually torque is the one unit where Imperial has a trifling advantage. It is usual to express torque in ft*lbs and work in lbs*ft, whereas in SI they are both Newtons*m (or mm)

[Tim HammondParticipant @timhammond72264]

One of the nicer jobs I had in a varied career was driving an articulated lorry, and I well remember a French driver measuring a load to go on the back of his wagon. How did he do it? By pacing out the length and width with one foot in front of the other – in other words in French feet…

[Mick B1Participant @mickb1]

I built a sit-in toy car for the grandchildren. It said 'Made In Europe' and 'Printed In Poland' on the box.

I had to open up the holes in the wheels for them to run freely on the axles.

I found the axles were 9,51mm in diameter. No prizes for guessing that Imperial-sized BDS, minus the usual undersize clearance but with thickish zinc plate, was still in use here.

[Nigel Graham 2Participant @nigelgraham2]

Duncan –

Thankyou for spotting my error…. The label is actually printed Ncm. I'd smply mis-read it.

'

Several years ago I saw the programme for an organ recital in Oslo Cathedral, celebrating its return to service after heavy overhaul. I do not know when Norway went metric, but the instrument's description quoted all the stop names in fus (feet). "Diapason 8fus", etc.

Network Rail appears still to use the Mile, Chain and Yard, and anyway the Statute Mile and Yard are still the only legal standard road-distance units in the UK.

'

Another area where French units have stayed discreetly away seems to be in bell-ringing: a bell is quoted by pitch and weight, or "mass" if you must, but in cwt. & qrs. Good!

Why French units? Invented there! When that country had recovered from its Revolution and the following shambles, it took a grip on its lack of any real system of measures, which varied not only by trade but also regionally.

At least the UK's system was national although there were at one time some trade units like the bushel and a glorious range of beer cask sizes of which the Barrel is only one. The casks' names were defined by standard Imperial Gallons, and anyway the beverages are now packed in only a couple of industry-standard casks and kegs, but as with other things it is a shame when the drive to flatten everything to suit remote bureaucrats and patronise school-children, loses fine old names that hurt no-one and add individuality.

I don't understand though France established the km hence m on a measure of the Earth's circumference as well as could be measured in the 18C, rather than using the Nautical Mile, which I think already existed. The NM, and its derivation the Knot, is directly based on angle of latitude – rather forecasting the Radian!

One thing I deprecate is the American spelling of these French unit names – let us at least respect the etymology despite Webster's Dictionary, so measure metres with meters, leave grams to Mum's Mum, and loiter not on the liter!

[Chris Evans 6Participant @chrisevans6]

Re the ignition points gaps with the engine running better with 12 thou as opposed to 15 thou. Is this not why we started using "Dwell Metre's" ?

[Nick WheelerParticipant @nickwheeler]

Posted by Nigel Graham 2 on 23/10/2020 08:53:31:

Another area where French units have stayed discreetly away seems to be in bell-ringing: a bell is quoted by pitch and weight, or "mass" if you must, but in cwt. & qrs. Good!

Most of the towers round here quote them in cwt and kg. Ever tried telling an 11 year old that the bell he was just ringing weighs 5cwt? It's a waste of time, because you also have to say that it's about 250kg. I was fifty this year, learnt to ring 34 years ago, and bells are the only thing I've ever measured in cwt. And then it only makes 'sense' when attached to a rope and wheel. Which is meaningless because a bigger wheel on the same weight 'feels' lighter!

I worked as a barman for several years and nobody ever used the names of barrels, just their quantity in gallons.

The sooner these obsolete measures die out the better.

[Martin CargillParticipant @martincargill50290]

My Tuppence worth (or should that be 1p worth?)

1) About 15 years ago I was calculating the size of radiators that I required for the house I was renovating. I was using an on line calculator that required room and window sizes in metres. I despatched my son to measure the rooms (he was around 15 at the time), He came back with measurements in inches. Playing devils advocate I explained to him that I needed measurements in metres. He went away and disappeared for about 15 minutes, coming back with his mother. The two of them then proceeded to tell me that it wasn't possible to measure the window in metres, because it measured less than one metre…..

After a lot of explaining I realised that neither of them understood the relationship between millimetres, centimetres and metres, nor did either of them realise that 0.7 meters was a valid measurement. It was further complicated that my sons school taught centimetres and these were not marked on the tape.

2) About 10 years ago I was Installing a German machine. At the commissioning stage I had a German engineer working with me, he asked for the loan of my tape measure. After two minutes of trying to measure a size he handed my tape back and went off and got his own. I asked him what was wrong and he explained that because our tape measures have imperial on one side and metric on the other they are very difficult to use, because no matter how you try 50% of the time the measurement you want is on the wrong side of the tape. Don't believe me? get hold of a metric only tape they are so much clearer and easier to use (provided your working in millimetres).

3) Regarding the centimetres and millimetres problem, around 40 years ago my mother worked as a secretary for a Swedish steel fabrication company. At the gates of the factory there were two large ship sized anchors. They were there as a reminder for the workforce to always check the measurements on drawings. Turns out the drawings for the anchors were in millimetres and they had been manufactured in centimetres.

Martin

[Nicholas FarrParticipant @nicholasfarr14254]

Posted by Martin Cargill on 23/10/2020 11:04:50:

My Tuppence worth (or should that be 1p worth?)

snip

2) About 10 years ago I was Installing a German machine. At the commissioning stage I had a German engineer working with me, he asked for the loan of my tape measure. After two minutes of trying to measure a size he handed my tape back and went off and got his own. I asked him what was wrong and he explained that because our tape measures have imperial on one side and metric on the other they are very difficult to use, because no matter how you try 50% of the time the measurement you want is on the wrong side of the tape. Don't believe me? get hold of a metric only tape they are so much clearer and easier to use (provided your working in millimetres).

snip

Martin

Hi, I can relate to the German engineer, a frustration that I often had during my working days and I still get it now at times in my own garage. Biggest problem is, that not many DIY stores seem to sell metric only tape measures, I did have a couple of cheap ones from Tesco's of all places and they lasted a fair while, a much better one I have came from a local tool supplier but are more expensive than the duel ones.

Regards Nick.

[SillyOldDufferModerator @sillyoldduffer]

Posted by Nigel Graham 2 on 23/10/2020 08:53:31:…

At least the UK's system was national …

Not really. Imperial is as foreign as metric. Avoirdupois pounds, abbreviated lbs from the latin librae, are from le système des poids commerciaux. Doesn't sound British to me!

Is it good to consider Weights and Measures patriotic? They're tools not symbols of national pride. I suggest a technically based country should adopt the best tools for the job and firmly resist any desire to super-glue itself to the glorious past for sentimental reasons. It's what we do next that matters.

Dave

[Nigel Graham 2Participant @nigelgraham2]

By "national" I meant "nation-wide"; not by history. Other countries had created systems that were regional.

I never considered measurement units as "patriotic" but it is right to credit those who invent them. Nor did I advocate "super-gluing" the country to the past where and when inapplicable to do so.

I don't know the origin of Avoirdupois* but French was the language of much of diplomacy (and commerce?) for a long time after Latin faded into the background.

'

Incidentally, if we are all supposed to use SI units, and use them appropriately, why do or did some car manufacturers specify engine powers in something called "kp" (kilopoules apparently – 1000 Hens?), and do quote vehicles' internal volumes in litres, the liquid measure?

I am not worried much about power and am happy with 1HP = 0.75kW as near as dammit for an ordinary motor- car; but do want to know what size objects the car will carry, whether I choose feet or metres, not turn it into an aquarium.

'

===

*Avoirdupois: "Have some peas".

[old martParticipant @oldmart]

I'm 71, and I cannot remember ever seeing one of the wooden school rules which didn't have imperial and metric divisions on it.

The museum's lathe is imperial, and one mill is and the other mill is metric. Half of my manual measuring instruments are metric, only the digital calipers are bisexual.

Edited By old mart on 23/10/2020 20:26:24

[David CauntParticipant @davidcaunt67674]

Peter,

I had always thought that a billion was 10 to the power of 12 not 9?

Dave

[old martParticipant @oldmart]

There was a time when a billion was a million million, but now it is a thousand million.

[Nick WheelerParticipant @nickwheeler]

Posted by old mart on 23/10/2020 20:42:34:

There was a time when a billion was a million million, but now it is a thousand million.

That's so American numbers look bigger than ours…. did

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