Metric vs Imperial

I think it went well pas the 60's!

I had a 1984 Mercury Topaz that was a mix and match plus I recall my 1989 Ford Taurus sedan that I had to do some engine work on by replacing head gaskets having a mix and match as well.

I also have a few gallon pails of old automotive fasteners and bolts from older vehicles I have scrapped out and its mix and match of standard metric and half and half nut bolts and what not. I keep it around just because I never know when I may need a 10 MM threaded bolt with a 9/16th's grade 5 head on it!

I think Ford was doing the mix and match for years.

I recall traffic signs in NY informing that the next exit was 1/10 of a mile ahead. Shouldn't they read: Next exit 176 yd ?

Now...what is that in inches!?!

Drew K

Because the nearest convenient measuring device is the vehicles odometer and that reads in 1/10's of a mile.

But wouldn't it be smarter to use Kilometers? That way you don't have to worry about mixing measurements. How easy is it to figure out how far 3.37 yards is in any other imperial measurement?

It lacks common sense to use an imperial measurement. Just saying "because we have always done it that way" is no excuse...should we go back to writing with quills and india ink just because they did it that way for hundreds (thousands?) of years before the ballpoint pen came out?

The other excuse, that it will cost too much to change is stupid too...how much does it cost to have different measurements on everything? I can understand highway signs because it will cost millions to change them (perhaps that is why England still uses miles?)

Drew K

"How easy is it to figure out how far 3.37 yards is in any other imperial measurement?"

Its just as easy as figuring out how many feet there are in a meter or a thousand of them for that matter!

How many city blocks in a kilometer?

It goes both ways you know.

Personally I think the Imperial system is good being its not designed for those who are lazy or don't like math!

" but a very large number of US inhabitants have no clue on how the imperial system works."

True, but they should. Ignorance is NOT bliss.

When I was working, they kidded me because I liked decimals, not the architectural mixture of feet and inches. That is, I liked 5.08 feet or 61 inches, not 5 feet-1 inch. It could be feet, inches, meters, or whatever, because decimals is what you put in a calculator.

That is ridiculous! It has nothing to do with laziness, it is efficient and it reduces errors in calculations. Lazy is not wanting to change because people would have to get their head around a concept that an inch is about 2 and a half centimeters.

It is like when the Romans converted to using the decimal system. How would you like to do calculus with using ∏ or e in roman numerals? They changed to the decimal because it makes sense...changing from Imperial to Metric just makes sense, it is the logical efficient thing to do.

Sticking with Imperial would be like buying a Humvee for fuel economy.

Drew K

Wow, That was awesome! I remember being starteled the first time I saw x! I thought it was just an excited variable.

Drew K

Your answer is only is incorrect with the the respect that 1cm = 0.393700787 inch.

Every body in Europe who has done PCB design hates the number 0.3937!!! consider a connector with 256pins in a row and the resulting differences for the last pin compared to the first if you calculate even with 2,54mm distance between pins. The connector might not easily fit to the PCB!

If the spikes were both metric, there would not have been a problem. On the other hand, if the spikes were both Imperial, again no problem. In that situation, spikes should have been available in both systems. Someone just didn't forsee a possible problem.

The debate in my opinion reduces to: 1. Elegant imperial fractions system or 2. Consistent decade system that is also used almost on every other entity measurement except of course, time (There we have the 60 seconds, 60 minutes, 7 days, etc, that ruin the consistency). So that's where the real debate should be, consistensy and not at the units themselves. Now days that economies everywhere but China are declining, and we just can't pretend any more that we don't see it, there's not much room for such intolerances. Borders are pretty open now, and I don't expect any dramatic changes on that soon. And insisting on something that has NO other effect but reducing your exports, and makes your decline steeper, is not very wise. Now to the subject. I see the sentimental and some practical of course, reasons imperial-educated folks resist for, but it is not expected from them any faster attitude change. They must be persuated first that we're not talking about a culture defeat here, we're talking about waste of energy resisting to something that brakes a tradition born with limited future, and surviving only in ICU. And any compromise like the one OP proposes, has no advantages over the existing condition, it will only add more inconsistency, and more lost time. Personal views of course. S.M.

My favorite (and most frustrating) example of poor acceptance of metric is by General Motors. In the mid-eighties, they started using M6.3 x 1.0 fasteners -- mid way between 1/4" and 6mm.

Of course, when you are working on the car and need to replace an old bolt, you try a 1/4-20 or 1/4-28, but they don't quite fit. An M6 x 1.0 is just close enough that you think it'll work -- until you try tightening it.

It is a world wide problem in all aspects of measurements,weight,pipe threads,plug/ sockets, voltage, frequency etc. ISO should come forward to standardise these.

Pretty sure a volt is a volt and frequency is based on universal time constants everywhere.

Red- Imperial Units

Grey- Metric Units

The metric thread, imperial head screw is a good example of compromise for the sake of reducing confusion. Only drawback is that such a compromise isn't applicable in the huge universe of metrology.

Considering the USA accounts for ~1/5 of global manufacturing capacity, Imperial Units is here to stay unless the economics shifts in favour of the change.

Until then, I keep a conversion chart handy

I screwed up the other day a form asked for my sculpture dimensions in cm
As an engineer I use mm on m when being metric.
Fortunately an E-mail resolved the problem.

On my bows I use metric (mm ) for small dimensions and imperial for longer ones. I never get confused until some muppet starts on 'cm' and before anyone protests that they are are part of a well constructed measurement system to base 10.
I give you the decimetres which AFIK isn't used anywhere.

Lets re-intoduce the decimetre just to screw everything up
Del

The logic of those brought up with the imperial units is astonishing to me! Isn't it easier to remember that a DECImeter is 1/10 of the meter (the closest upper measure),,, or 10 times bigger than the centimeter (the closest inferior measure), rather than calculating 5/8 of an inch, or remembering that 1 inch is 0.0833333 of a foot??

You miss my point.
cm are not in common engineering use. dm are not in use at all.
I'm in favour of using appropriate measurements.
Most of the metric system goes up in factors of 10^3 not just 10.

I would say it's much harder to confuse an inch and a foot than it is to confuse a mm and a cm.
In fact I'll quantify it:- The foot/inch is 6/5 less confusing than the cm/mm
Del

And you havn't even mentioned the Hecto or deca prefix...wikipedia didnt even show the deca (1 decameter=10 meters)

Drew K

Hi Del, in the daily life one uses only 4 lenght units: Kilometer, Meter, Centimeter and Millimeter. In the industry small sizes are expressed in millimeters, and tolerances in 1/10, 1/100 or 1/1000 of a millimeter... and thats it! Easy to understand and to calculate.

Some years ago, I placed an order for 304 SS tubing at a very large US company by phone.

I told the lady I wanted the tubes cut at 1.50 meter lenghts.

Concerned, she replied: sorry sir, we run imperial.

Ok, please have them cut into 5 Feet long pieces.

Silence....

Silence....

Understanding something was going wrong I asked: can you please have it cut into 60 inches lenghts?

Yes sir was the reply

The moral is: not even people brought up using the imperial system know how to use it

On one of the archery webites one guy was really excited as someone had felled a Yew tree, he got there and found they'd his 8' log into 2' lengths so it would be 'easier to handle'.
heartbreaking... 4' lengths he could have spliced together but 2'
Del

I don't want to stir up a new storm of pros and cons;

Then why the post?

I believe that most that have to deal with measure have learned to use both. So I have no problem with either. Would it be easier if it was just one or the other. Sure it would! But to mix bolts with metric thread and imperial heads. Why? Have never found metric bolt that I couldn't remove with an imperial socket and vice versa.

73.13 feet equals 877.56 inches

Then no one would say 73.13 feet it's 73 feet 1 9/16 inches. We can debate about the .0635 mm discrepancy.

Imperial or metric isn't it the same measure. I wish that converting from one to the other was the hardest thing I had to deal with in life. Life would be a breeze.

To the general public it may not be so easy change. Give it time it will.

Sure, either will work, but you will usually screw up the head if the bolt is torqued down tightly. I believe refering to a dimension such as 73.13' is only used in surveying. 73'-1 9/16" is used in architecture. 3 and 4 place decimals is used by machinists

Acceleration due to gravity on earth = 9.8m/s/s, an ugly decimated fraction.

Acceleration due to gravity on earth = 32ft/s/s, a nice whole number!

A convenient coincidence? Hmmm...?

But neither is correct.

More like 9.80665 m/s² or 32.174 ft/s

The metric one is closer.

Actuallu it's worse than that - according to Wikipedia:

• Gpoles = 9.832 metres (32.26 ft) per s²
• G45 = 9.806 metres (32.17 ft) per s²
• Gequator = 9.780 metres (32.09 ft) per s²

Come on USA - finish the "we've gone metric" job.

Well, 'm afraid the metric system will wait a while. There are too many of us 'old farts' still around who still visualize in Imperial sizes. I was an engineering inspector for a who;e lot of years using both systems and I still can't visualize in metric. If I'm reading something that has metric measurements, I still have to convert it to Imperial before it is a visualizable thing. Driving around in Canada a few years ago, I really needed the convertible speedometer in the car. Do I use metric? yes. But I'll never be comfortable with it.

Good point Johny - So far the discussion seems to have just missed one link.

I am a (chemical) engineer who grew up with imperial and studied using them both, switched to metric working in UK in 70s and 80s, then back to imperial when working in N America. I am fairly happy in both - but the real answer is to use SI. (Systeme Internationale). As a Brit I recognise there is some resistance to stuff originating across the English Channel and even moreso perhaps for Americans, but the the Europeans got this one right.

There is no need to try to remember whether or how to include g as a fudge factor in your formulae (except for the specific case when considering gravitational acceleration) or use units like poundals. The SI system has units that respect the names of our illustrious predecessors - Newton, Joule, Kelvin, Watt, Pascal, and has simple relationships between them, that even I can remember. The familiar base units of kilogram and time units are retained.

I am afraid that I agree with all those who say America is living in the past. I understand the inertia, but the prize (survival in changing world markets) would be worth the effort. If it hasn't already, it has to start in educational institutions and could take a generation...

Having two incompatible measuring systems is about as useful as "Daylight Savings Time"

A quote attributed to an elderly native American about daylight savings time:

Only the government would cut a foot off of the top of a blanket and sew it on the bottom then think they have a bigger blanket.

Not an exact quote but you get the idea...and it is in imperial cause its 'merican.

Drew K

A lot of it has to do with "seat of the pants" engineering. When I'm designing something, experience may tell me that a 1/4 -20 bolt is sufficient to hold it together. If I go metric, say 6mm, I'm downsizing the fastener slightly and I don't trust it. Those of us in Imperial machinist land never use feet, yards, bushels, or anything that doesn't distract from decimal inches (12.000000 inches, divides by 10 easily, and makes metric unnecessary). Besides, I have a tone of English taps and dies, racks of bolts and other fasteners, why change? It's just old habits.

Since I deal with old junque, when I think of "Imperial" I think of Whitworth, BSA, and such (English, British, or Imperial.)

On the whole, I think the whole world should go with metric. The conversion or changeover for us would be a pain because of all the tables, charts, etc; but it would be an easier system to use once we got used to it--it probably would take a couple of generations.

In the automotive world I seem to live in, both are everywhere. I once did a Pinto engine conversion. 1.6 to 2.0 I think. In switching the accessories, I came across a stud that was metric and imperial. I just learned to look.

As for standardizing, try this on for size. In the 80s the govt was pushing for the metric conversion. Chevrolet had been making its little V-8 engine since 1955. But now was being pressured to use metrics. Every bolt, nut, and drilled hole on that engine was done with imperial measurements. Should Chevrolet now manufacture every part on that engine with metric dimensions? And how about the poor repairman? when he needs a replacement exhaust manifold, should he still be able to buy an imperial one, or does he need to but new brackets and hardware for the accessories that bolt to that manifold?

During those years, there were some changes to metric, and we all hated it. As you would change a water pump, you would find out that the alternator was metric. the power steering pump was imperial. The air conditioning compressor was metric. The water pump was imperial again. And the air pump could be either way.

There was just no easy way out. It seems that as components were redesigned for some reason, the new design would be metric.

The engine remained in service till phased out as an imperial hardware design. But accessories were "as needed"

I had to replace the flywheel on my 2.9liter Ford Ranger as the mechanic who replaced the starter for the previous owner used 3/8-24 bolts where the metrics should have ben used. Proper bolts $4.85 ea. at dealer, $.98 at the local hardware. Pull the driveshafts and transfercase/transmission to replace flywheel...a pain in the arse because some 'mechanic' couldn't tell the difference between 11mm and 3/8.

I don't care what system is used, or how they are mixed, I just want people I trust to do work to KNOW the difference and HOW to check. I think there is a severe dumbing down of public school graduates that wind up working in the 'trades' that can't convert or don't want to learn. More 'fun' to watch TV, or play video games.

Too true! I saw a list of topics taught in the 5th grade in the 1870's one time and it was in comparison with contemporary 12th grade topics (early 1990's). A random group of HS seniors couldn't touch it! Now, do we want to get into Civics??? The dumbing down of our schools is a direct cause of our poor performance in the election system. Never mind who gets elected, how many people can't be bothered to vote? I'm ranting I know, but if we don't reverse the trend we'll really be up the creek.

BTW, my stepfather had one of those 5th grade educations from the early 20th century and he was a power maintainer in the NYC subway system. Want to try that now with a HS grad?

And they are trying to dumb us down further with endless vareities of 'tamper proof' screws and a risk averse, letigious society.

Del

I had to learn both units of measurement and units in Physics at the time at school. No wonder I was confused what with ergs and dynes and British Thermal Units. Hundredweights, chains, furlongs etc I could go on. Then as an apprentice it was convert 3/32" to a decimal in your head. Thread sizes, metric and imperial thread angles. The list goes on Zeus book in your top pocket. Funny thing is kids learn metric but will say they are 5ft 6inches or weigh 9 stones. I try really hard to think metric these days its much simpler.

Didn't the engineers making the Hubble mirror mess things up due to some sort of confusion in units/tolerances in imperial and metric. Or was it a rumour