Back to Imperial

[Mark RandParticipant @markrand96270]

When working on steam turbine performance tests in the '80s, I tended to think in terms of psi and °C when I wanted to visualise things. I still do.

All of my machines are basically imperial, but the milling machine has a DRO and the lathe has dual metric/imperial dials. I work in whatever units fit the job, the materials or the tools to hand in most cases.

 

PS:- putting the crown stamp on pint, half pint and 1/3 pint glasses always made more sense than the CE mark. It's a singularly British/UK concept, although the Australian pint is very close. It never featured as common usage in any other EU country.

 

Having said that, the fact that David Bl***y Frost is having it reintroduced makes me want to retain the CE mark due to the mess that he and his mates made of the negotiations to part from our friends across the channel.

Bah! Humbug! Mostly down a 750ml bottle of Green Jack Baltic Trader Stout.

Edited By Mark Rand on 18/09/2021 21:33:10

[Bill DawesParticipant @billdawes]

Peter, I came across an old impeller drawing a few years back, one of my souvenirs from my DO days back in the 60s, in fact it was a 'blue print' so may have pre-dated the 60s and it most certainly had dimensions in 64ths.

I also have a couple of catalogues of Alldays & Onions products dating back to the 1800s, everything in there seemed to be described as 'new improved' or 'patent'.

I wonder if we will ever convert from mpg to km/litre, strange most of us, including the younger generation as far as I can see, still refer to mpg even even though we have bought fuel in litres for years now.

Bill D.

[Clive HartlandParticipant @clivehartland94829]

A report today say the the US school system will teach metric as from 2023. so if the US goes metric all the rest will follow.

[Anonymous]

FWIW to some, I didn't say that fractional dimensions weren't used in imperial drawings. Simply that the use of imperial doesn't demand them.

And, in the whole of my working life (I'm approaching 80) in aerospace, computers, mechanisms dna analysis equipment etc, I never actually came across any drawings using fractions.

The fact that examples of drawings using fractions are extant doesn't affect either of those statements.

[SamsarandaParticipant @samsaranda]

I have a set of drawings for my Allchin Traction engine that are old drawings published by Percival Marshall Co Ltd, they must be the first drawings that W J Hughes produced, they are of course imperial and use fractions, it’s so long since I used imperial fractions that I find myself so frustrated searching for the decimal equivalents, solved the problem by printing the equivalents chart from my Zeus tables in enlarged format and posted conspicuously over my bench so they are always available. My memory is so shot that fractions are like a foreign language it’s so many years since I used them. Dave W

[Colin WhittakerParticipant @colinwhittaker20544]

So now we can go into the pub and order 1/2 a micro acre foot of best bitter (including the head).

[Speedy Builder5Participant @speedybuilder5]

CONCORD(e) used thousands of 3.2mm rivets – that's 1/8" in my book ! Of course, the UK drawings showed rivets with 3.2mm diameter with imperial spacing !!

[Mark Simpson 1Participant @marksimpson1]

Interesting discussion,

To earn cash (so I can buy more materials to make more swarf ) I've worked for a CAD System developer for the last 30 odd years…. Our customer world is largely metric, quite a lot of US companies do some metric work but still loads of inch stuff there that's not going away…
(There is a growing tendency to speak about "Feet and Inches" or "Foot/Inch" rather than "Imperial" even the American government calls it "customary units" these days)

BUT…..
We've just finished a large project, for a US customer, to implement fractional inches for Pipe Isometrics. They want different denominators for Tube Lengths, coordinates and bend radii and have pages of specification about how to show dimensions of Whole inches, whole + fractional inches, Feet and no inches, feet and a fractional inch…
We've done more work on Inch dimension code this year than in 30odd years, and we didn't expect to extend it ever again… Strange World.

[Martin ConnellyParticipant @martinconnelly55370]

The pipe isometrics sound like a major backward step. I got our design and draughting department to stop doing drawings for pipes that were just a piece of bent tube. As we had a CNC bending machine the best way to designate the pipe was as a set of coordinates. That made the shape independent of the bend radius of the tooling used. We had assembly drawings as a result with up to 40 small pipes made from 1/4", 3/8" and 1/2" tube where there was a couple of views of the assembly with bubble numbers to each part and a couple of pages of coordinate tables. We never had scrap from parts that were bent in a mirror image or were the wrong size because the wrong bend die was used once we did that. As there was no visual guide to the shape in a lot of cases we put in the design standard that inspection was simply if it fitted it was correct. The saving in the number of drawings was an important reason for going ahead with it.

Martin C

[Nigel Graham 2Participant @nigelgraham2]

Some years ago I happened to see the programme for a recital to welcome Oslo Cathedral organ back from a major overhaul. The instrument's description gave the voice names in fuss (feet!) – thirds of 'em too, in some cases.

One would think so too. How could you possibly fit "Diapason 2.438m" on a stop-knob, let alone think it would sound better than a "Diapason 8ft"?

+++

I worked for a while in a sub-contract engineering company and we had drawings in Imperial and others in mm, depending on the customer supplying them. One was German, so the language on the drawings was German let alone using mm! Of the inch sizes, some drawings did use fractions and decimals depending to some extent on the accuracy needed, with the fractions being +/- 1/64 ".

+++=

Perusing some of the above contributions…

'

The Crown mark on a beer glass does the same as the CE mark – shows the glass has been manufactured to its appropriate weights-and-measures standard.

'

The official system is not simply the Metric but the ISO's version of it, the SI.

Having used certain SI units at work… It sacrifices day-to-day practicality on the altar of High Sums and Bureaucratic Order, worsened by naming all the compound units after people to make Dimensional Analysis awkward. Though to be fair, them as makes the rules probably not affecting them personally, do rather grudgingly let us use the angular Degree and pressure Bar.

(A 5" g loco needs millions of those silly little Pascals to get moving , but is quite happy to win IMLEC on 6 Bar. On the other hand a Sound Pressure Level of 1Pa would deafen us, happy to breathe at 1 Bar but to listen with ears sensitive down to 20µPa minimum (0dB re that level) sensitivity…)

+++

American schools have tried teaching Metric units; and American scientists do use SI. It's noticeable now that when you hear a module-landing commentary from NASA, they read the altitudes in metres.

[Mark Simpson 1Participant @marksimpson1]

Martin C "The pipe isometrics sound like a major backward step.."

I agree with you when it's a bit of bent pipe, especially when you make it multiple times, but the customer is creating industrial piping and each iso can contain low hundreds of pieces of tube and fittings. The isos are made automatically from the model and split into several sheets if there are too many bits. It shows you how to orient flanges, valves and tees etc. not just the tubes, so a complete fabrication and erection drawing.

We do export coordinates for NC bending machines but not everyone wants it. There is a preference these days to use elbows rather than pulled tubes where possible; depends on what's available in the material… Bending big pieces of 300NB+ tube can also be a challenge; we have one customer whose bending machine is over a 4M deep pit to accommodate the flailing ends of the bent pipe…. They use lots of special materials and there are few fittings readily available.

Possibly the biggest difference between Industrial/Plant piping and adding pipes to a mechanical design is that they are one-off things… The drawings are created automatically, pipes are fabricated to them, installed to them and the design company move on to the next job.

It's especially interesting to me that their end customer builds a metric "product" but its supporting installation is totally built in Feet and Fractional Inches…

Fascinating (and probably endless) discussion…

[CirclipParticipant @circlip]

So, back in the sixties when Ingineering was supposed to change to metric in GB., it was hard to do a full change over so one had to become bi-sexual for not only lengths but later in money. Despite working in metric, I still did (and do) go through mental gymnastics converting back or forwards to get a "Feel" for a tangible size. Since dressmaking sizes are taught to the youfs, 25cm means s*d all to me but 250mm is about 10".

Then skipping on a few decades and job changes we go into the electronic industry and find that although the PCB panels are laid out to metric dimensions, the pre forms for things like transistors and ICs are IMPERIAL spacing thanks to Uncle Sams refusal to go metric. No problem for one offs but for thousands? and then having press tools made to punch hundreds of holes through the laminate to mount the components. Given that all measurements should be generated from an X-Y datum point, the use of sub datums to the individual component become more important, so dual dimensioning. This of course for wire ended components, pre Surface mounts. Must have been difficult for the Australians on Metric Day.

Regards Ian.

[DMBParticipant @dmb]

School science lessons were so much easier in metric, rather than buggering about with archaic rubbish like BTUs. One of the best events of recent years was dumping duodecimal money. Fart-hings, x 2 = one ha'penny, x 2 = one penny, x 3 =a threpenny Joey, x 2 = a tanner(6 pennies) x 2 = a Bob/ one shilling, x 2 = two Bob or x 2 1/2 = a half crown. Then 10 Bob notes × 2 = £1note x5 = £5note, which we still have.

What a load of old crap dating back donkeys years. Nothing wrong about the age, just the awkwardness of calculations. Same goes for weights and dimensions. For those who don't know, old penny noted as a 'd' which is an abbreviation of denarius being a Roman coin. The shilling likewise, was an 's' Roman solidus.

We just need to stop Networkrail from continuing to use 'Chains'. No doubt there are many more examples of the old medieval system.

I am happy to use whatever I am confronted with, all my machines having Imperial leadscrews and dials to match. Model engineering metal stock much easier to obtain in Imperial sizes and use metric screws or Imperial, depending upon what their use is. Tools/ accessories for mills/lathe etc use metric easily obtainable locally. Use conventional Imperial screws on models. Loco and clock drawings all Imperial, doesn't matter too much to me. Harold Hall's books and grinding jig drawings in metric with metric threads. Fine by me.

John

[Oven ManParticipant @ovenman]

Posted by Circlip on 21/09/2021 09:06:49:

So, back in the sixties when Ingineering was supposed to change to metric in GB., it was hard to do a full change over so one had to become bi-sexual for not only lengths but later in money. Despite working in metric, I still did (and do) go through mental gymnastics converting back or forwards to get a "Feel" for a tangible size. Since dressmaking sizes are taught to the youfs, 25cm means s*d all to me but 250mm is about 10".

I was only taught imperial at school so had to convert to metric on the job so to speak. I have never used cm and we never used them at work so I don't understand why cm are taught in schools. For the sort of things we built at work, working to 1 decimal place in millimeters seemed a much better idea than working to 2 decimal places in cm.

I like to think of myself as "linearly ambidextrous", but there is no way I could go back to feet and inches now.

Peter

[RobinParticipant @robin]

The problem with metric is that third digit on the DRO or digi-caliper.

The hours I spend setting it to perfection on the cross slide only to see it blasted out of existence the moment tool tip meets steel.

Come back thou, all is forgiven

[Speedy Builder5Participant @speedybuilder5]

France uses the cm a lot – imagine the surprise on the glazier's face when I asked for some picture glass 450 x 350 x 2.5 (45cm x 35cm x 2.5cm !!!)

[Tony Pratt 1Participant @tonypratt1]

Posted by Robin on 21/09/2021 10:14:21:

The problem with metric is that third digit on the DRO or digi-caliper.

The hours I spend setting it to perfection on the cross slide only to see it blasted out of existence the moment tool tip meets steel.

Come back thou, all is forgiven

Ignore the third digit

Tony

[DalboyParticipant @dalboy]

When woodworking I tend to go straight to imperial when measuring and marking out. Having said that if a plan or something that is in metric I can also use that equally as well.

[Clive HartlandParticipant @clivehartland94829]

Having worked for a Swiss firm for many years the there never was a split of metric measure, it was always meters/millimeters. 1.155 as an example. Not once in 37 years did i see cm used to give measure.

[SillyOldDufferModerator @sillyoldduffer]

Posted by Nigel Graham 2 on 20/09/2021 21:47:00:

…

The Crown mark on a beer glass does the same as the CE mark – shows the glass has been manufactured to its appropriate weights-and-measures standard.

…

Pedant alert!

Alas not!, the beer glass Crown was an Excise Mark, confirming the capacity of the glass for both customer and the Government. CE is a conformance mark: sellers add it to assert the item meets relevant EU standards, which are usually safety related.

Provided it's honest, CE assures the customer the item is safe to a standard acceptable in all European member states. Governments don't care much about them. In sharp contrast, the crown mark was only valid in the UK, and the Crown cared very much! It was a reminder to the trade that alcohol was taxed. Customs and Excise made rigorous checks and had more extensive powers of entry than the police and inland revenue. Avoiding excise duty was a serious criminal offence, and the government dropped like a bomb on offenders. Being an offence against the crown, expect the maximum penalty!

Crown and CE Marks have nothing to do with quality. The beer in a Crown glass was often a bit 'off' as I remember, but once sold, then tax is payable. Likewise, CE marks can be stamped on rubbish, and there's no come-back as long as it's safe. And even if the item is hazardous no action will be taken unless Trading Standards give it priority, which is unlikely because they've all been slashed back since the 1970's.

These days the crown mark is unnecessary on glasses because pumps are calibrated for tax purposes. Putting Crown Marks on glasses now has no meaning other than nostalgia. About as daft as my local herbalist, who once claimed their shop to be a 'Nuclear Free Zone'. Yeah right!

Dave

[Mike PooleParticipant @mikepoole82104]

Ale hand pumps are not measured delivery and most or the lager trees deliver as long as the tap is open. A hand pump might deliver half a pint per stroke on a good day but they are rare, if the bar staff are a bit green then a top up is often required. Electric pumps are rare in this part of the world.

Mike

[Anthony KnightsParticipant @anthonyknights16741]

At one time, measured pumps were introduced to serve beer into oversize glasses. ( exactly 1/2 pint at a time ) These proved to be unpopular with the licensees, as they couldn't make anything on the head. These days, at least around here, it's either hand pumps or free-flow into pint glasses. That way you get between one and two fluid ounces short of a pint and the pub makes more money. Probably doesn't apply down South where they like beer without a head.

[Nick WheelerParticipant @nickwheeler]

Posted by Anthony Knights on 22/09/2021 12:31:57:

At one time, measured pumps were introduced to serve beer into oversize glasses. ( exactly 1/2 pint at a time ) These proved to be unpopular with the licensees, as they couldn't make anything on the head. These days, at least around here, it's either hand pumps or free-flow into pint glasses. That way you get between one and two fluid ounces short of a pint and the pub makes more money. Probably doesn't apply down South where they like beer without a head.

Measured pumps are reliant on the rest of the system being up to scratch. As soon as the cellar/barrel/delivery line temperature changes, or the pipe cleaning is a day late, or the button isn't cleaned with the correct chemical, or the clouds across the moon are too thick, the measured quantity changes. So you end up with a row of glasses with varying quantities that you hope the customer will accept being poured into their glass. Wastage goes up through the roof, profit drops through the floor and the scrap pile gains another heap of expensive junk.

Here in the south, I won't accept a southern beer that's been forced through a sparkler to create a head that isn't appropriate. A northern beer also shouldn't need the sparkler to create a head; it should be a natural part of pouring the pint.

[colin hamiltonParticipant @colinhamilton16803]

When I used to work offshore, practises were still dominated by American custom so most things were imperial. We had to measure the drill pipe and sum all the individual lengths up. To make it easier they decimalsed the feet, so a foot had 10 (long) inches in it. We were issued with specially made tape measures!

[Nicholas FarrParticipant @nicholasfarr14254]

Hi, talking of pints and short measures of beer, back in the latter part of the 70's, slightly larger capacity straight pint glasses became more common which had a white line near the top to show a full point measure, which I guess allowed a pint to be drawn with a head and would be at least a full pint after any head had settled down. One night I was in a pub with some friends and we were at the bar ready to order, there was a guy who had just been served a pint and it was below the top of the glass and he asked why the glass wasn't full. Another guy standing just the other side of him pointed and said about the white line shows the full pint, at which the first guy turned to him and in a rather grumpy agitated voice "I was asking the bleeping barman not you" we all looked at each other with raised eyebrows and I think someone in our group said quietly "that shut him up"

Regards Nick.

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