Imperical to Metric: What's the Big Deal?

Timber is a problem.

• Sheet engineered boards are sold in Imperial sizes (8ft x 4ft sheets) and metric thicknesses (4mm, 6mm, 9mm, 12mm, etc.)
• Most timber merchants sell timber by the "metric foot", 300mm or 11 ⁵/₈in, which can leave a lot of waste when trimming to fit the above boards.

Pipe threads are imperial, as they are across the globe, though threads for other things are in metric: attempting to obtain a 1" x 8TPI Whitworth bolt will yield nothing.

Road distances and speeds are in Imperial.

Beer is now back to Imperial (hooray!); instead of 568ml, one can buy a pint again.

Weights were being converted all to metric, though shopper resistance has deflected this, and Imperial measure is again lawful.

Right old mess, isn't it?

Wow! I thought the U.K. had embraced the metric system. Having two systems is the problem. It needs to be one or the other.

Everything was fine until those French units arrived.

I was wondering when the "French Connection" would come up.

I wonder how long before the "sacred cubit" rears its head in this discussion.

Hello Guest,

There is nothing wrong with the cubit! And the same can be said of the chain. BTW Cricket embraces this as the distance between the stumps ........... end to end.

One Imperial measure which is not about to be altered is the Mile. Often changed or referenced on maps, it would simply cost too much to replace each and every Street/Road Sign which references Miles. This may include Road Markings also.

With reference to the sheet Steel mention by an earlier post where the thickness is in mm and the Length and width are Imperial. I wonder if this is because machines would be too costly to replace and or modify, or whether the L x W of the sheets are in Metric which matches a size in Imperial?I know soon after the change to Metric some sheet sizes of wood, carpet etc were in fact Imperial but, the size was converted to the nearest mm!

Take care.

Take care.

I have run into the "weird" plywood here in the US too. You can no longer trot down to the local Home Depot (Hardware store for you foreigners) and buy a sheet of 1/2 inch plywood. Oh sure they will sell you one but when you look closely at it, you find it is no longer 1/2 inch thick but 12mm. Printed right there on the face for all the world to see is "12mm". Guess what, it doesn't work. When it is butted up against a piece of "real" 1/2 inch plywood, there is always that tiny ridge between them that you just can't seem to ever work out. Oh well I didn't really expect that carpet to last for over two or three years anyway. I always wanted a slit right there where the ridge wears through...

The story of NASA's lost Mars orbiter has got to be the funniest and most expensive mistake attributable to the switchover.

It was admirable that they admitted it - in Europe it would have been covered up under some phoney pretence or other - but still it was funny ....

http://edition.cnn.com/TECH/space/9909/30/mars.metric.02/

It really was admirable. Kudos to the NASA admin that approved the press release. You Sir, have balls.

Sorry to barge in

The key is not metric or imperial (of course I personally mind it - we are metric as you know and get into lot of problems when we import our components from US - we land up in imperial threads and we do not have the fasteners or even eye bolts for those to handle )

But the basic part is culture - here the children are fully dependant on parents till they start earning - and hence to throw them out, we have to make them earn-able and hence the stress is too high on their studies and the things like that. Then they study, become self dependant and then go to USA- it is unfortunate but true- as much as you dislike them coming over (you mean in general) - I personally do it too. Of course they all say the facilities - but it is actually the greenbacks that lure them. You know, nobody wants their best ones to leave- but then we might have been superpower earlier .

Frankly back to the topic, the science (the way it has been universalised in English), the measuring system also could have been done so, it would help not you or me, the overall community.

Still I have a lot in PSI and other imperial units and then I have to convert back by multiplying or dividing with 14.6 for the kg/cm2 and same things with quite a few other units. This confusion as weel as the errors could have been avoided.

do you know that India by our standards is a "Third World" country switched over to the metric system in mid 50's and in a few days everybody adopted it down to the uneducated villager in a remote village. It seems we in the US are either too lazy to switch over or like the failure of the NASA Mars mission, perhaps a little too--------- for a change!

GA

ED come into my office now. We are switching to metrics tomorrow. Throw away all of the tools you have purchased for the last 35 years. You may keep the screwdrivers, pliers, adjustable wrenches and of course the hammers. Please replace what ever you throw out with suitable metric equivalents by the first of next week. Have a great day.

Hello bob c,

I liked your post about the switching to Metrics!

In the UK we are in 'no mans land', being in between the older specs of the UK, the Metric, and the US specs. I and I am sure other who work on differing product makes must keep at least three sets of fixed end spanners! It is a real mash up!

Take care.

Does that mean I get to keep those great thinwall Sears Craftsman chrome vanadium steel sockets and box end wrenches I bought 50 years ago? ........Ed Weldon

I still show them as missing from last year's inventory. Please report to Tangible Properties. You might want to bring your union rep with you.

Hi Ed,

The irony of it is that going Metric will mean there is at least as many Imperial sockets and spanners sold as Metric. As some need Imperial for work and it all depends on when their car or truck was built at to if they need Metric or Imperial.

The one advantage to Metric is it is all the same, 'reading from the same book kind of. With Imperial there is/was about 5 or six specs of threads, heads etc.

Can anyone shine a light on why there are so many 'star' shaped screw drivers? It started out with 'Phillips' then 'posi-drive' ........ ad-infinitum ..................... I think the screw manufacturers started all this off so you use the wrong driver and 'round' the head and then have to drill it out and replace it with a new one.

Take care.

There was some one on CR4 a while back that was touting another fastener style as the newest and best design for maximum torque transfer. I was not able to find it, but well, that's just me. The theory is that a person will be able to transfer more torque without danger of rounding out the bolt, or driver.

Hello Bob,

Thank you for the reply post. I can understand a cross shape but anything else means the area of driver trying to move the screw is less and less on the fasteners which have six, or even eight star points? Crazy!

Take care.

Was that by chance a 'square' socket drive? The square shape is actually one of the strongest in terms of torque and contact area. Although the Robertson (TN) drive dates back to WW2 days when these were used by the millions for wooden hulled PT boats and the metal was called 'Everdur' silicone bronze, the square socket did not find favor in the US boat building business. One company that did build quality yachts was Hatteras and I have heard old time boat builders refer to the square socket as 'Hatteras screws' . In Canad the square drive is used everywhere because it does not strip out and delivers maximum torque. You are more likely to shear off the screw head than strip out the socket or screw driver tip.

When I was a production manager for an electronics firm we used to ship one square headed driver with every order for rack mount equipment. We found that easier than changing our screw fastening system.

its hard to get rid of a tool that when they say lifetime warranty they mean it..............even when the tip of the screwdriver is broken....(pryed off)....

Hi phoenix911,

I know exactly what you mean. I cannot understand why the thin plastic highly ridged screw driver handles are sold at all. They take hell out of your fingers. The best are the old original type of wooden handled driver. I used one for 30 years! And never ever used it to open a paint tin!

Take care.

Ed can you elaborate on why the metric fastener system stinks. Is it because metric foot pounds are smaller and thus do not hold as much?

The thread fits are too tight and become a problem in corrosive environments. Also threads have to be cleaned off more thoroughly before assembly if the working environment is dirty like in many maintenance activities.

Also there are way too many thread size/pitch/hex head size combinations. This may be useful if you are designing aircraft for weight saving; but it is a big pain in the maintenance shop. Some outfits like Toyota and the other big Japanese auto companies got smart and standardized which sizes to use in their products. (you can almost completely disassemble a Toyota with a 10mm wrench).

And lastly I have a belief, which I readily admit to not having studies and verified myself, that the thread forms are not as strong as the US thread forms.

Ed Weldon

Ironically, most aircraft fasteners are Imperial.

Hello Rorschach,

You say "Ironically most aircraft fasteners are Imperial".

It may be because more than half the aircraft in the world are built in the US? Which as has been said is still Imperial.

Take care

Actually far more than half. There are probably ten times more Boeing 737's in the air than Airbus A320's, A330's, and A340's combined. And there is also the issue that once a fastener is approved by the FAA, aircraft manufacturer's are pretty much married to it.

Hello Rorschach,

I appreciate your reply post, thank you. The amount of planes was just a rough guess, sorry.

Take care

Which also brings up the point that, given the number of crashes of each aircraft type compared to the number in the air and the time in service, I seriously question the competence of EADS/Airbus Industrie. The planes are freaking deathtraps as far as I'm concerned. I was stuck on an A320 on the flight from Dusseldorf to Frankfurt last Saturday and it took everything I had to keep calm. Luckily the weather was virtually perfect flying weather so I didn't have to worry about having the freaking rudder shear off.

My feeling also, that airbus was inferior to boeing, but was impressed by the Dhl Airbus that took a missile warshot in the tailpipe ,( Bagdad early on at the rodeo},and still managed to land. Also recent use of Airbus in Hudson River as field expedient jet ski.

If only they could keep the important flight related components attached, maybe external guy wires or revert to bi-wing and dual tailplane, that way if component falls off, head for nearest body of water. Plan all flights within glide ratio distance of rivers or over ocean. " This is your Captain, one of our rudders has prematurely departed the aircraft, prepare for a water landing( isn't that an oxymoron?), please remain seated until the aircraft has come to a complete stop at the dock".

Hello Ed,

GA to you Sir.

Your reasoning makes complete sense!

Take care

Thanks babybear. I have lived many years among engineers, trained in the metric system, who I would argue the issue with. After a while I began to understand the underlying causes of our resistance to metrification.

It all really got started in my head 30 odd years ago when a local Calibornia fellow named Stuart Brand published his Whole Earth Catalogs. Somewhare in the middle of that activity he published a piece about how the imperial and other culture based measurement systems came about and especially how they evolved to fit the human scale. That's all humans, not just the scientists and engineers. That was the eye opener for me.

Turns out that if you look at comparable measurements between the metric and imperial systems you see some metric measurements that fit our scale well, like kilometers vs miles, liters vs quarts, millimeters by themselves, meters vs yards. grams and milliliters by themselves. But there is no good substitute for pounds, ounces, gallons and for me especially mils and tenths that are the common stuff of the machinist.

Just some further thoughts of mine on the subject.

Ed Weldon

Hello Ed,

very interesting piece!

When it comes down to it on the more diverse thread sizes and types, some threads are suited better to certain uses. An obvious example is the large pipe sizes that would be hard to use without a coarse thread?

When it comes down to working on Lathes and working with drill sizes it just takes a mind to realise it is easier to entirely change, and not try to try to convert back and forth to Metric and or Imperial. It aint that simple though. In Maintenance there will always be situations where you will need to use a metric size and try and make it work or fit.

I recall working on a house which was built in about 1920. And the bricks were differently sized to metric ones. The metric were 2mm thicker. Which meant where there was a tight coarse I had to grind part of the old brick away to allow a mortar-bed for the metric bricks I had to use. I was doing an 'extension' and had to cut out every other brick to 'tooth' the buildings together.

Being human we naturally think of what we know, and do a quick mental math to convert and reach the answer. It can take a bit of getting used to though, as when working out volumes it always seems too large?

Take care my friend.

No major probs...Public understanding of gram kilogram etc can be a bit vague, but you just buy a bag of sugar, you don't actually worry about the weight.
Some industries are still mixed e.g Many electronic components are still on a 0.1" pitch, but some times it's in the data sheet as 2.54mm
Pursonally I think in imperial for stuff like longbows and arrows, but once it gets below about 1/4" I can think in mm.

At the deli counter, I usually ask for the meat to be sliced..
"1/8 of an inch, 3mm or the thickness of a pound coin, whichever is easiest for you to visualise"
Admittedly this is sometimes met with a blank stare.
Del

P.W.Slack in response #1 appears to have a different opinion.

I agree with PWs observations...they just don't bug me too much.
It can be a pain where timber is in imperial measurements sometimes like 8'x4' and other boards are in metric...mind it can mean you don't have joins all in the same place.
Maybe I'm an optimist?

You pays your money you takes your choice....

I'd guess all serious engineering drawings would be in metric...
But I'm sure PW will find an exception in the big stuff he plays with.
I'm pleased that distances on roads are still in miles and our speedo's read MPH

100MPH 70mph still has a nice ring to it.

Del

I always go to the same deli and just tell the kid, slice it on number 9, having shopped there for years, I know this is the setting on the slicer I want...

Yeah...so why don't they have a little chart for the customers with the numbers and a picture of the thickness so you can ask for what you want...?
Oh I spose I could suggest this at Sainsburies and then wait while hell freezes over in the vain hope of some activity...that's assuming I could get the attention of of one of the 2 people behind the counter, who seem to think that paperwork and tidying up is more important than serving customers.
Whew I feel better for that
Del

Ah! Sainsburys are rolling out customer feedback surgeries, according to a programme on Channel 4 last night. About time too!

Great Question - all I know is it costs the bejeezus to keep 2 tool-sets to work on things....wrenches, sockets etc, etc, etc

Back in the day, I could eyeball a bolt, nut, whatever & tell you what it was (imperial)

Now ya gotta guess, fiddle around....sux

The worst part is some items have both Imperial and Metric on them. My tractor is a Royal PIA to work on some things are metric some are imperial. Have to get both sets of tools out anytime you work on it.

We started to switch to metric on Federally funded projects like highways a few years back. But then you had a small problem with the conversion factors used because some contractors still wanted Imperial showing on the plans. And all your details had to have both in them. You wouldn't think it would make that much of a difference until you have a highway project that is 100 kilometer = 62.14 miles +/-, actually 100 kilometer = 62.137119224 mile and your coordiantes don't match your centerline stationing when you have them printed out side by side.

Not that any contractor build anything that tight but. But they sure threw a hissy fit. when shown the comparison.

Wish they would finally decide to change to metric and phase out the Imperial stuff all together. Sure it will take some time to get the OLD mind to think in metric but thats still easier than trying to think in both.

My tractor is a Royal PIA to work on

You think you've got problems!!

PlbMak really has to get out more....

???????

Wait until you have to wear glasses. Now none of the bolts that you look at will fit the wrench you get.

Here in the far South , Argentina , we deal both in metric and imperial, despite that we have the SI as the official meassuring system.

Atmosferic pressure where told at the radio and wheathercast in mBar , but as the SI is the Official now it is told in HPa , or HectoPascal , 1000 Hpa is the normal atmospher pressure, just to keep the people mind about the former 1000 mBar.

Many years ago it was FORBIDDEN to show the screw and nuts sizes, in Imperial , despite it is the usual shape used by all , it is easy to find 1/8 , 3/16 and 1/4 " sized, a 3/8 " by 1 inch . comes writen as 9.52 mm x 25.4 mm, also we have the screws in NC and NF numbered 6 8 10 and witworth too , a big mess is that often when whe use a 1/2 inch , it could come in 12 or 13 tpi , acording it is NC or Witworth.

Also it is forbidden to trade a RULE in inchs and metrics.

Even, screw metrics sizes are expensive than imperial sizes.

Angles tee and bars comes in inches , pipes in BSP, but in powers hydraulics we use NPT , but also BSP and Metric.

We have cars , trucks, both from US, Europe, Japan , India, and so on.

A funny thing happens about 20 years ago , when the Ford Argentina merge with Volkswagen , to be a new firm.

So when the enginnering department join , motor and transmission where in Imperial , and body was in Metrics.

All main hardware shop , have at the shelf imperial and metrics, but in the deep inside country you will find all in imperial.

Metal mild steel sheet are 1 x 2 m and 4' x 8' , but all in AWG , and for 1/8 and up , a true mess 1250 x 2500 mm to 1500 mm x 6000 mm , we have not mm thickness, exept in INOX.

Round tubes structural comes in imperial.

Structural tubes square or rectangular , sided in mm , but thickness in imperial.

Concrete steel rebars in Metrics.

But steel beams are metrics UPN and IPN.

Of course pipes are ASTM B53 asa scheduled

In foods , all is metric , except jam and mermelades , all are in metrics but by 454 gram , just a pound, just for export reason.

Pressure for tires and air sistem in pound/square inch.

Hydraulic power in Bars and also in # , flow, most in Gallons/min , but also in Liters min.

Scales in Kg .

Distances in Meters and Km .

Fluids in Liters , but we use all around the 55 Gallon drum , or about 200 liter

So If you are aware of how to deal with it , take a trip here.

That is the most screwed up system I have ever heard of. Sounds worse than the mess here in my country. Now that I have heard from Argentina, the U.K. and India, it would be interesting to hear how all other countries have faired. I would suspect countries like China, European countries and Japan are all solidly metric.

Hi Ronseto , seem to be we share age. I'm 60 now , so I grew up to thecnick just when we change from the UK to the US "technical domination" , but by that time 1955 we start up manufacturing cars and trucks , cars from Kaiser , jeep was the firts vehicle , and Fiat making it's famous 600 car , a few time after GM and Ford star production too , and Chrysler licence its manufacture in a local family firm.

We also made AUTO UNION , BMW, HILLMANS, PEUGEOT , AND THE FAMOUS CITROEN 2CV and 3CV.

Then Renault bougth shares in Industrias Kaiser Argentina , thus becoming IKA-REANULT ARGENTINA , and then take full command and now it is Reanult Argentina. By that time we make the American Rambler , and the Reault Dauphine,

One assembly line in Imperial , the other in Metric.

I begun my Technical School at the INSTITUTO IKA a plant school in one corner of the plant terrain.

So we have to learn the fractional to metric sizes.

We have calipers in metric and in Fractional or decimal imperial.

As far as know , Japan is full metric , exept in pipes , they use ASA schedule too.

ASA schedule pipe thread or weld , seem to be the only all arround used , but in USA in NPT , and all over in BSP .

Russia also in metrics.

India , I do not know , but as they where under the UK , they could have both metric and Imperial.

By our zone , South America, the same as in Argentina.

So do not worry , nobody die the day before.

Gabriel.

I'm glad you got back to me on this question. When I was still part of the work force, (shipbuilding) I had to work with both systems. I was comfortable with it although others were not. I've always wanted to go to Argentina. I've been to Chile a few times because my wife is from there. I think the only things that would give me trouble is SI units other than dimensions and speed.

I was surprised when I moved to Malaysia that things are not consistently metric here. I suppose any of the former British colonies still have remnants of imperial embedded in culture.

Roads and speed are in metric here, most weights are in metric, but you can buy a pint of beer, and clothing sizes are in inches in many places.

In the oil industry we are a bit schitzo as well measuring oil production in barrels per day and gas production in standard cubic feet, but then measuring pressures in bar and temperatures in degrees C.

I see what you're saying, and your point is a good one. However, take a look at ( or have a friend do it) how poor your English and grammar is. Don't you think that part PART of the problem lies/ starts here ?????

Here in the USA, I grew up without knowledge of metric, except for temperature.

I'm too old/lazy to memorize conversions, so my metric frame of reference is 9mm.

South Africa started the process around 1968 meaning that I did my schooling in the imperial system and tertiary education using the SI system. They were very strict about enforcing the change and would not allow the sale of "bilingual" measuring tools or (after a short transition period) the use of the "old" and new systems together for food items or in the newspapers. We thought that the change would create havoc with our mostly third world and rural people. It did not, the change was surprisingly easy. We still have the problems as mentioned in many previous posts, wood products (and certain pipe threads etc) are often still quoted in inches, but the official measurements are SI.

My children think only in metric units. They still talk about having a pint, which in SA is not a direct conversion, but a much more pragmatic 500 ml. The word pint to them is merely a description of a large beer and has no imperial volumetric significance.

I, and most of my generation, am happy in either system. However, ALL engineering documents and design calculations etc are in SI units to the best of my knowledge. There are exceptions at times for equipment from USA. but then they are a bit confused; I received a document the other day where the unit used was "gram inches" - talk about mixing systems and a recipe for misunderstanding.

My children just look blank if I use feet, inches, rods, poles, perches, leagues, furlongs (still used in horse racing) bushels, pecks etc.

This link gives dates for the year of official metrication of many countries. Looks like only the USA, Liberia and what was Burma (still find it hard to change that name) that have not taken the plunge to metricate to some or other extent.

South Africa Metrication

(from an official government news release on 1977 September 15 in connection with the completion of metrication in South Africa)

On 1967 September 15 the Honorable Minister of Economic Affairs announced the appointment of a Metrication Advisory Board to plan and co-ordinate the change-over to the metric system in South Africa. One of the first decisions of the Board was to introduce the Systeme International d'Unites called the SI for short, which had just been developed at that time and had already been accepted in principle by many countries as the eventual metric system.

A Metrication Department was created within the framework of the South African Bureau of Standards to implement the decisions of the Advisory Board.

Not only the fact that the decade that has passed since 1967 September 15 suits the decimal character of the SI perfectly, but also the fact that the Republic has become a metric country within the originally planned transition period of ten years makes today's date a fitting one. The success achieved is largely due to the good co-operations received from commerce, industry, agriculture, the professions and other organizations, all government bodies at the central, provincial and local level, and, above all, the ordinary citizen. Without this co-operation such a profound change affecting each and every one of us would not have been possible.

South Africa is widely acknowledged as a world leader in the field of metrication and in the application of the SI system. Many countries now in the process of changing over have studied the South African change-over and are following the same pattern to a large degree. With the USA as the last large non-metric country now engaged in changing over and the existing metric countries also replacing their systems with the SI, it is clear that the SI will soon be the only system of units used in the world.

South Africa is proud of the leading role it has played in this important matter.

My children just look blank if I use feet, inches

Try asking them how tall they are. Although I think it's finally changing here (UK): for years kids would claim they didn't understand those old feet and inches but ask them how tall they were and they'd come back with feet and inches.

I have seen that with my peer's offspring.

This and also talking in stones about weight.

I guess it is just them trying to twit us oldsters as we probably all did in our youth.

I still have to go and check the weight of a stone when I hear that.

You are right about most people reverting to imperial when talking height, I am 1,86 m tall, but if someone asked me I would most often say "just over six foot one" and this is still common here (RSA).

However, my children always give there height in metric units and do not even know what it is in feet and inches. This maybe indicates the relative success of our conversion.

Here in Panama, we don't worry about which system- vise grips fit any size bolt, a torch will cut most anything, and screwdrivers make good chisels. Panama is officially on the SI bandwagon, but no one told the populace...

In Canada, we have lived through the transition from Imperial to metric. Except that is wasn't a full transition. When you do a project for the government, you use the SI system. All dimensions are specified in millimeters, not centimeters, not meters and certainly not feet and inches. A dimension of 12.5m would be shown on the drawing as 12 500 (note the gap between the 2 and the 5, but not a comma, the reason being that a comma could be read as a fly speck or an accidental marking).

We hear weather reports on TV in Celsius, but the older generation still wants to know what it is in Fahrenheit degrees. Otherwise, they don't know whether to wear their long-johns or their shorts.

Structural steel firms have fully adopted the SI system. So when you design a commercial building, you normally use the SI system, except when the client doesn't understand the SI system...then you use feet and inches...unless, of course, the authority having jurisdiction insists on using the SI system, after all, it is the law in Canada.

When it comes to wood framing, the metric system has not been completely adopted by the populace. There are those who specify dimensions in the SI system, but often, clients, owners and workers on the job prefer feet and inches .

Plywood comes in 48" x 96" sheets (1219.2mm x 2438.4mm). If you want a metric sheet (1200 x 2400), you can get it but you have to pay more for it because of the two saw cuts to bring it down to size. So you pay more for a smaller sheet. Nobody wants to do that, so they don't.

The result is that our structural drawings show 38 x 235 @ 406mm o/c where we used to call for 2 x 10 @ 16" o/c for a roof or floor framing plan. If we don't do that, the plywood and OSB will not meet over a joist.

There is no question in my mind that the metric system is a more logical, simpler, more consistent and better system than Imperial, but the problem is, we have to convince the users that this is so. Until we do, we will be using both systems for ever and will never gain the benefits which the metric system can offer.

[I'm not real sure that metric conversion by any kind of fiat would help us all that much. Such regulations could well have the effect of substantially increasing manufacturing costs especially for low production volume technical products.....for smaller scale manufacturers who tend to buy components that are not made to custom order the price of US metric components tend to be a whole lot higher than imperial.]

The increased cost of switching over would be a one time cost that could be absorbed in time. No switch is ever without cost.

[Going metric, would better our chances of competing in the world economy]

I think it would. Most countries prefer to buy from neighboring metric countries to avoid the Imperial/metric differences. American autos are not popular in other countries because they cost more to repair. Imperial tools are needed when all their tools are metric. The American auto industry went metric, but only as far as fasteners were concerned because it was the most cost effective solution to satisfying metricification. All other components were still manufactured in Imperial terms, like engine components. Engine capacity is still stated in cu ins. Manufacturing an engine to metric standards would be a very expensive plan. If all our cars and consumer products were 100% metric, I think they would be more acceptable throughout the world. This is only my opinion and is not backed by any solid proof.

Ronseto, In Canada the American cars are all marketed with metric sized engines ie displacement in Liters not cubic inch. Frankly it does not seem to be a factor in purchase choices. Your comments about american cars costing more overseas has moer to do with tarifs and taxation than metrification. In Denmark where I come from car price is determined by engine displacement. Bigger displacement = bigger price. This price escalation extends to licence plate and insurance. Which is why most foreign vehicles have smaller engines compared to US designs.

Transportation distance does have an influence also. but that works both ways. Over here foreign cars seem to cost a premium and part of that cost is having to ship it half way round the world. But inport tarifs is still a bigger part.

The argument that requiring dual sets of tools increases cost is not a huge factor. My Husky brand set of wrenches came with both metric and SAE (Imperial) sizes.

The cost of the Brand specifc special tools required to work in a dealership is far greater than the cost of having both metric and imperial sizes. Here metric or Imperial is not a factor. Excluding independent garages from being able to work on new models is the key element. Hence the need for 'special tools' unique to that model and brand of vehicle.

We have already moved into a global economy. you cannot control which country gets a contract to build a specific sub assembly or single part. And one country's metric size fasteners is not always the same as another country's metric size.

I find a European 10 mm bolt has a different size head than an American 10 mm bolt. Also noted on some Japanese cars. The metric tools I used on my Honda was not the same size as what I needed when working on a Swedish Volvo or a German Volkswagen.

.

Elnav -- We really should separate the fastener systems from the general arguments over the metric system.

In the case of the fastener systems the pros and cons revolve around the standardized fastener and thread designs in each system as well as the round number increments and even the nomenclature. The fact that one is metric and the other is imperial is really incidental.

But the metric system itself is much easier for engineers, scientists and other technologists to deal with. On the other hand the imperial system as well as all the other local measurement systems are the result of evolutionary processes that made them a good fit for the human scale and perception of the environment.

Arguably the metric system is not always a good fit for situations in our lives; but we seem to adapt to it. There are lots of awkward examples of metric measurements. A few have already been mentioned here.

Personally I like the imperial system because that is the one I learned as a youth and that is the one that forms the basis of my visualization of quantity measurements. Beyond that the hands on mechanic/engineer in me is surrounded by mostly imperial system stuff, hardware, measuring tools and convenient engineering formulas. So my preference is obvious. And I bristle at the idea of any government trying to cram the metric system down my throat for situations where it is for me a bad fit.

On the other hand we live in a world where many of our most serious problems have an analog measurement component that needs to be understood by all stakeholders including voters. In the USA, a real big player in this arena, we have a vast majority of people including leaders who have a hard enough time understanding and communicating elements of these issues without having to be confused by the overlaps of two measurement systems. Just look at the issues of energy policy.

To me this is the real gain we would have by nudging ourselves in the USA more toward the metric system. I'm not saying we should accept their lousy fastener system without some further standardization of sizes.

But what I think would be a good move would be for the political parties in the US Congress as well as at the state legislature levels to agree to leave the imperial system measurements out of their public statements and legislation especially where it has anything to do with energy policy. Even if they can't agree to anything else at least they ought to agree to using the same language as the scientists and engineers working to solve our energy problems.

But....(sigh) ...... I think it will be a while before we figure out what to do with "barrels of oil"...... .

Ed Weldon

Ed I agree completely. My purpose in mentioning the fastener was to highlight the human element and other fctors being of more significance.

I was born and raised in a metric country. But having moved to Canada I was then re-educated in the imperial system. All my technical training was in the imperial system and I find myself struggling ( sometimes) with the necessary conversions to metric. It's the human element factor that is going to be the real crunch.

A good illustration is our food industy. We still speak of a pound of butter despite having a block of it measured in grams and paying for it that way. The retail food industry finally got the legislators convinced to allow dual measurements at the retail counter. I think of a pound of meat, a quart of milk and a gallon of gas even though I mentally convert as required. Curiously enough deli counter sales are strictly by the gram. People do not ask for half a pound of sliced meats. They ask for 100, 200 or 500 grams of this or that. The price tags do list both.

AS far as trade is concerned, I really doubt going metric would change US export business by a significant amount. Other factors will have much greater significance. These are factors that have little if any relevance to the system of measurement used. A fuel guzzling vehicle; be it gallons or liters per distance unit, is still going to guzzle fuel. If the destination country taxes by horse power and engine displacement then the tax will be the same whether its measured in kilowatts of power and liters of displacement.

As for any industrial equipment, the individual companies will convert when and if required to get a contract or make a sale. . Public acceptance is quite another matter. Just look at the food industry to name one example.

Where I see a possible problem is when physical dimensions relate to operational function. When a metric sized wire is fed from a Breaker rated in the imperial system mismatches can occur. European wiring uses 8A, 10A and 16 A as their common sizes. In North America we use 15A 20A and 30A as the common sizes.

A mechanic accustomed to a half inch bolt having such and such a yield strenght may get confued by the metric sizes and select one millimete runder instead of over. It fits without having to drill a bigger hole and it looks okay. But strenght of material remain the same. so now you have an undersized bolt subjected to the same load as before.

An installer accustomed to tanks and pipes rated in PSI may accidentally select the wrong fittings when confronted by ratings in kilo paskels. therin lies the real problem and source of rejection instead of acceptance.

In Canada we had a glaring example of imperial metrix mixup. A plane was refuelling in Montreal. The fueller was thinking in gallons but the tanker truck was measuring in liters. Yep! She ran out of fuel half way there.

The pilot and co-pilot made a dead stick landing on an abandoned airport near Gimli Manitoba. Naturally Air Canada tried to blame the pilot calling the succesfull landing and avoidance of any injury "pilot error". The real culprit of course was the mid stage transition from imperial to metric and inadequate training of staff.

An ongoing problem is the fact our imperial dollar went metric and we have been short changed ever since. A buck only buys half as much as it used to do.

I remember reading about a 767 landing there without fuel, it got named 'The Gimli Glider' after that.
Apparently the strip was being used for some informal drag racing at the time.... it gave 'em a shock seeming this strange silent jet hurtling towards 'em
Del

You and I have "spoken" before, Del. Some positve, some negative. I don't know if you remember, I had made a negative comment on the importance of accuracy in spelling, grammar, etc as it applies to engineering, and used this exact airplane reference.... thank you for remembering for me (couldn't think of the names).

Here is one big costly example of the dual system. Back in 1964, I worked for a shipyard that was doing a navy tanker rebuild. The project was to cut the tanker in half and weld in a 100' section to make the ship longer. The new section was contracted out to another country(I think it was Japan) for manufacture and shipped by barge to the U.S. for inclusion into the two halves of the ship. The new section fit perfectly as far as the overall width was concerned. The longitudinal beams that run fore/aft, met at the centerline, but as they progressed further outboard, they started to not line up. By the time the outer width of the hull was reached, the misalignment amounted to over an inch. The problem became evident. The ship was built using the Imperial system and the new hull section was built in the metric system. The fix was to burn a foot off the ends of the longitudinals on the new section and transition a new piece of beam to the ends of the longitudinals to form a jog. This occurred on two ships, the AO106 and 109.

This is why the adjustable AFS spanner is so useful - "Any F****** Size"!

I was in the UK with Imperial and later we switched to Metric, whats the problem? I can work in either and I can convert, though I mostly work in Metric nowadays, living in a Metric country!!!

I drive in Europe with KMH and in the UK in MPH, I can still keep to the limit, even though my car has onlöy KMH marked, but I can convert in my head near enough to not "arouse" a Radar Speed Cop.......

Are so many people so STUPIDLY DUMB "single minded" that they can only cope with one or the other???????????? Surely not!!

I actually still have a few old Imperial tools in my workshop and have fun working with them occasionally on metric wood sizes......keeps the old grey cells from rusting up!!!

[Are so many people so STUPIDLY DUMB "single minded" that they can only cope with one or the other???????????? Surely not!!]

I think you are wrong there. Those who can cope, like yourself, are very much a minority. Unless you are trained in the scientific community, dual systems are not easy or convenient. If I read a description of an item, and dimensions given are metric, I have to mentally convert it to Imperial in order to visualize it's size. This is common with everyone. If a recipe calls for 350 grams of flour, again I have to convert it to Imperial to visualize the amount. I can do it and you can do it, but don't assume that everyone else can also do it, at least not as quickly as you can.

Hello ron,

For most people the metric/imperial debate really does not matter much. Where it does matter is in manufacturing. Now, there is not many people in a factory who are responsible for the 'finalized' size of a bar or the finished product. It may be only 5/6 % that NEED to know, the rest of the workforce just assemble the item.

The finite and importance of say matching bearing would have already been done in the first design and all the pieces after that are 'finished' size for whatever is being built?

As I say in my other post and you have mentioned it as well, it is the matching 'old' with 'new' where the problems occur, but people who work where this occurs get used to 'making things fit'! So the general population has no idea of the problem which have been solved. They just buy the item.

Each of us has our own 'favourite' way of converting 'ounces' to 'grams'. But one thing that I found made things tricky, was in a 'bar' of butter. In the imperial' measure I could cut a 'half pound bar', into half and half again to get 4,2, and a single ounce. I could not do that after the metric system came in.

Take care

bb

With Imperial, each measure has a raft of terms, eg inches, feet, yards etc. With Metric you only have to remember the base term, eg meter, and understand the prefix - mm, cm, m, km etc. There's actually less to remember.

I switch between systems fairly easy, even though I grew up with imperial. It's easy enough to carry rule of thumb approximations in the head ( eg a pint is roughly half a liter). Bag of sugar = 1 Kg. Think of a familiar object that has a round figure value in each system. To be more exact, you don't need that many conversion factors in your head for every day use. With use, the units gradually sink in with people no matter how long they've used another system. It's just a case of finding conversion strategies that work for you.

When the UK went decimal with currency everyone predicted meltdown. It was chaotic for a long time, but mainly because people didn't want to change to the new-fangled stuff.

If you were suddenly emersed in a metric system, I reckon you'd pick it up pretty quick. If you moved house within the US, you'd get to grips with local dialect/idiom/accent fairly quickly. The existing UK system is a bit of a mad mixture, but it's not as hard to live with as the impression you may be getting. Mrs K still hasn't twigged when I say 'I'm nipping out for a quick half'*, so it's not all bad !

* The usual Brit assumption would be 'half a pint'. Actually, I don't think I've ever said 'half a pint' in my life !

..so that's half a gallon presumably

Tun

I adapted to using metric in every day life fairly quickly, but I still convert in my head quite often.

I also still have a tendency to convert from MYR to dollars whenever I buy something in order to decide if it is a good deal or not.

Good to see you back again. Now that you are convinced that conversions are not that difficult, can you convert Ozzie Osbourne speech into any language?

There is no direct translation of Ozzie speach into any language. No matter what it does not make sense.

So, how many milliliters in an egg?

At what stage of development?

A robin's egg or a rhea's egg?

You could use this, or maybe this. An easier approximation can be had via wiki-answers, such as;

"An approximate volume could be obtained by modelling the egg as a prolate ellipsoid.

The volume of an ellipsoid is given by (⁴/₃)(pi)abc where a, b, and c are the lengths of the semi-axes"

Are you a concerned Cadbury Creme Egg eater ?

How exact do you need to be ? How about measuring it by putting it in a measuring jug with some water in - see how much the volume goes up.

You'll have to be more specific about what you want to know. Is it for cooking quantity conversion or some such ?

....or maybe it's just a sort of 'curates egg' question about measurement ?

"It's easy enough to carry rule of thumb approximations in the head ( eg a pint is roughly half a liter). Bag of sugar = 1 Kg."

An approximation is not enough when shopping for food in a market. It is necessary to be able to determine cost per unit in order to accurately get the best value for your money. The same goes for gas (petrol). Supermarkets are notorious for pricing items that confuse shoppers. You have to know what the cost per unit is for one quart of Coke and for one liter of the same product to know which is the better buy.

Hello ronseto,

"Supermarkets are notorious for pricing items that confuse shoppers".

You are quite right saying this. I recently went to buy some coffee and at first, without thinking put the largest 'Jar' in my trolley. Then after a little thinking, realizes it was cheaper to get two Jars half the size!

As for working out the 'best value', as long as you figure things out in metric or Imperial, and not both, it is relatively easy to figure things out. But, as you say the Supermarkets tend to price in grams, and Kilos and it is left to the shopper to figure things out!

bb