bristolflyer
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Metric Or Imperial?

Mon Sep 10, 2012 10:32 pm

I was taught the metric (mm) system at school in England, now I live in the US which mostly uses the imperial (inches) system. I can see a good reason for using both - eg in construction everyone is used to 2x4, 2x6 etc and multiples of 4' for sheet materials. But when it comes to finer tolerance stuff I definitely prefer metric. When you get down to stuff that's 1/2" or less the metric system seems way easier.

I was listening to NPR today and there was an American designer talking about designing cell phones, he was talking in mm. What do the big electronics manufacturers use? I feel that describing something as '2mm' is was easier than '3/32'.

Anyone have preferences, and why?
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Dreadnought
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RE: Metric Or Imperial?

Mon Sep 10, 2012 10:59 pm

I prefer metric, but living in the US I have given up converting people. But I think the US will one day come around.
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lewis
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RE: Metric Or Imperial?

Mon Sep 10, 2012 11:05 pm

I prefer metric. 100 cm in a meter, 1000g in a kg. The scale of measurements makes more sense. In imperial, there is no round conversion between units and their sub-units (inches vs feet vs miles or ounces vs gallons).

I do prefer temperatures in F over C though. Even though C makes more sense in science (0 freezing point, 100 boiling point), the F scale is much wider and offers more accurate temperature readings for everyday use. In order to achieve that, we would have to use decimals in C when talking about the weather.
 
vikkyvik
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RE: Metric Or Imperial?

Mon Sep 10, 2012 11:06 pm

Metric is WAY better and easier.

But, my day-to-day life is governed by Imperial.
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Okie
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RE: Metric Or Imperial?

Mon Sep 10, 2012 11:15 pm

I think Pres Carter started the shift near 40 yrs ago with a goal of being transitioned by 2000. (30yrs)
Now it has been close to 40 years.

40 years ago the US was probably the major exporter and importer of manufactured goods world wide and had pretty much all the influence as far as manufactured goods were concerned.

The problem with switching to the metric system for the US was at that time there was no real supply chain or manufacturing chain in existence for metric machine tools ie drills, taps, dies, calipers etc. The only metric hand tools available were very low quality import at exorbitant prices due to low volume of sales.

Right now there is no push to change to metric since tool and machine manufacturers get to sell both (double the sales)

The same can be claimed for IEC/Metric vs NEMA/US electric motors.

An interesting deal that I ran into, a company that I worked for bought a piece of equipment from a "world" company that different sections shipped from different countries. A US section an UK section and one section from Denmark.
Something as simple as chain was a night mare US (inch pitch) BS British Std. (inch pitch but different width) and Metric.

Right now we run into issues with electric motors designed for both 50 hz and 60 hz.

So as long as manufacturers are doubling machine tool and hand tool sales there will be no major shift.

Okie
 
trvyyz
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RE: Metric Or Imperial?

Mon Sep 10, 2012 11:34 pm

I work in the EMI/EMC field and I sometimes use US standards.
Here is the MIL standard of US, if you scroll down a few pages and see the diagrams, the distances are all metric
http://snebulos.mit.edu/projects/reference/MIL-STD/MIL-STD-461F.pdf

This is from FCC website, all distances are in meters
http://ecfr.gpoaccess.gov/cgi/t/text...node=47:1.0.1.1.16.2.234.6&idno=47
 
B777LRF
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RE: Metric Or Imperial?

Mon Sep 10, 2012 11:41 pm

Quoting bristolflyer (Thread starter):
I can see a good reason for using both - eg in construction everyone is used to 2x4, 2x6 etc and multiples of 4' for sheet materials.

Everyone that comes from a country where inches was or is the traditional unit of measurement. I've got mates who own companies in the building industry, and they wouldn't know what a 4x4 is unless you wack them over the head with it. Houses, furniture, kitchens - you name it, it's all built to metric measurements in most of the world. They do know if they'll need a 10 or 12 wrench, but I don't think they'll even know that's an imperial measurement.

As indicated above, where inches will be really, really, difficult to replace is in industries where imperial measurements is an organic part, such as the tools industry. Aviation is another such example, with every single (western built) aircraft in existence is based on inches.

So while it will be very difficult indeed to introduce a wholesale transition to the metric system, for all "civilian" applications things are far less complicated and makes a lot more sense. Once you've gotten used to it the metric system is simpler, more logical, offers seamless transitions between weight, distance and volume, and is much easier to work with.
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KFLLCFII
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RE: Metric Or Imperial?

Tue Sep 11, 2012 1:06 am

All hardware on my Dodge truck is to metric standard, but fluid capacities and anything else that needs to be measured or torqued is listed in both metric and imperial. It doesn't bother me one bit.

Nor does it bother me that our sodas are measured in liters, yet our milk is measured in quarts or gallons. Liquors come in 750ml, but I can get a quart (or pint) of beer.

Common ammunition cartridges include .22, 5.56mm, .25, 7.62mm, .357, 9mm, .40, 10mm, and .45.

There are 60 seconds in a minute (time or angle), 60 minutes in an hour/degree, 24 hours in a day, 365 (1/4) days in a year, and 360 degrees in a circle, yet most of the world doesn't seem to have a problem remembering this...until the metric community conveniently forgets and preaches that all measurements could be simplified into a base of ten.

Just like languages, it's what we're born and raised with. I wouldn't expect the entire literate world to convert to one spoken language because the language may be "easier" in practice, nor would I expect each and every standard and measurement to become uniform among seven billion people. It is much easier, however, to perfect the conversion of units from one system to another...And in this day and age, with the right conversion factor in hand (with or without the use of technology), there is simply no excuse for a conversion failure. It's not an art, it's a science.

Any measurement is useless without a unit, and any attempt to process measurements of dissimilar units without converting is not a failure of the system, but a failure of the operator. Plain and simple.
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lewis
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RE: Metric Or Imperial?

Tue Sep 11, 2012 1:17 am

Quoting KFLLCFII (Reply 7):
There are 60 seconds in a minute (time or angle), 60 minutes in an hour/degree, 24 hours in a day, 365 (1/4) days in a year, and 360 degrees in a circle, yet most of the world doesn't seem to have a problem remembering this...until the metric community conveniently forgets and preaches that all measurements could be simplified into a base of ten.

Just like languages, it's what we're born and raised with.

That makes sense but when I wanted to get a grasp of imperial units, asking questions about it proved to be hard too. Many people will have to think very hard if I ask them "how many fl. ounces in a gallon?", "how many ounces in a pound?" or "how many inches in a mile?". Some did not even know, and I am talking about educated people. With metric, even if you don't know from the top of your head, it is much easier to figure out. I have been using imperial for the past couple of years and although I get it, it is not as convenient as metric, purely from a conversion standpoint.

Time is a whole different story. We deal with it literally every second of our lives so it is embedded in our minds. Having said that, if you take physics as an example, making conversions that contain time is much harder than just converting distances or weights just because of the lack of common factors.
 
Ken777
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RE: Metric Or Imperial?

Tue Sep 11, 2012 1:48 am

Imperial. Absolutely no need for the US to change.

First, the cost of a conversion is absolutely unnecessary. Every speed limit sign in the US changed just to "be metric"? Stupid.

And that is not the only cost. When Australia was converting my main argument was that the government would increase petrol taxes a penny a liter instead of a penny a gallon. Not my cuppa.

Reality is that those fields that need to use metric are already metric. You see that in medicine, but even there we see some losses. Imperial temperatures are more precise than metric, especially when looking at change.

Quoting KFLLCFII (Reply 7):
There are 60 seconds in a minute (time or angle), 60 minutes in an hour/degree, 24 hours in a day, 365 (1/4) days in a year, and 360 degrees in a circle, yet most of the world doesn't seem to have a problem remembering this...

That's because nature isn't metric.  
 
fr8mech
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RE: Metric Or Imperial?

Tue Sep 11, 2012 1:57 am

I really wish we had made the move over back in the 70's. Of course, we would still be dealing with a dual system due to legacy installation, but I can live with that.

I teach my kids both systems. My daughter was having a hard time with it, but my son is getting it.

Quoting bristolflyer (Thread starter):
2x4, 2x6 etc and multiples of 4' for sheet materials.

How do they build homes in Metric nations?
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bristolflyer
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RE: Metric Or Imperial?

Tue Sep 11, 2012 2:21 am

Quoting B777LRF (Reply 6):
Everyone that comes from a country where inches was or is the traditional unit of measurement. I've got mates who own companies in the building industry, and they wouldn't know what a 4x4 is unless you wack them over the head with it. Houses, furniture, kitchens - you name it, it's all built to metric measurements in most of the world.

That's interesting. The irony about the imperial system in the construction industry is that a 2" x 4" doesn't actually measure 2" x 4" - so converting wouldn't be that much of a chore!

Anyone know what units show on airplane drawings?
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Ken777
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RE: Metric Or Imperial?

Tue Sep 11, 2012 2:33 am

Quoting bristolflyer (Reply 11):
That's interesting. The irony about the imperial system in the construction industry is that a 2" x 4" doesn't actually measure 2" x 4" - so converting wouldn't be that much of a chore!

I can remember reading some years back that metric was easier for estimating construction costs, especially in preparing the bill of materials. The house we built in PER was "metric, but when I built a pergola I had to use Imperial as shade cloth was still 36" wide. I also believe that carpets were imperial (12' wide) as well.
 
Quokkas
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RE: Metric Or Imperial?

Tue Sep 11, 2012 2:43 am

Quoting Ken777 (Reply 9):
Imperial. Absolutely no need for the US to change.

Being brought up with both, I do like the quirkiness of the Imperial system: fathoms, cables and nautical miles. Then 16 oz = 1lb, 14lb = 1st, 8st = 1cwt, 20cwt = 1 ton. But the US cwt is only 100lb so the ton is only 2,000lb (the so-called short ton) while the Imperial ton is 2,240lb (the so-called long ton).

So even when comparing Imperial to metric, we need to remain aware of the differences between British and US usage as the measurements will not always be the same. It is not a problem when comparing length and area, but there are differences for capacity and mass. While an Imperial gallon is the equivalent of 4.54609 litres, a US gallon is only 3.78541 litres.

Now, if only we could get back to guineas, pounds, shillings and pence. How wonderful tuppence three-farthing sounds.  
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rwessel
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RE: Metric Or Imperial?

Tue Sep 11, 2012 2:45 am

Quoting Ken777 (Reply 9):
Quoting KFLLCFII (Reply 7):
There are 60 seconds in a minute (time or angle), 60 minutes in an hour/degree, 24 hours in a day, 365 (1/4) days in a year, and 360 degrees in a circle, yet most of the world doesn't seem to have a problem remembering this...

That's because nature isn't metric.

Only one of those (days per year) actually has anything to do with nature. The subdivisions of a day or circle are completely arbitrary (although a fair case can be made that the "natural" subdivisions of a circle should be 2*pi radians, or something related to that, although that would probably be less practical).

Quoting bristolflyer (Reply 11):
That's interesting. The irony about the imperial system in the construction industry is that a 2" x 4" doesn't actually measure 2" x 4" - so converting wouldn't be that much of a chore!

Even considering nominal sizes, a 5x10 (centimeters) would be only 1.6% off a nominal 2x4. Considering actual sizes, the difference would pretty much be within the manufacturing tolerances.


And folks - the U.S. doesn't use Imperial Units, it uses Standard Units (or more formally, "U.S. Customary Units").
 
StuckInCA
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RE: Metric Or Imperial?

Tue Sep 11, 2012 2:52 am

Quoting bristolflyer (Thread starter):
But when it comes to finer tolerance stuff I definitely prefer metric. When you get down to stuff that's 1/2" or less the metric system seems way easier.

I've been doing precision mechanical design (I worry about nanometers and microns) for many years and have had jobs where we did design in inches and jobs where we did it in metric (as in my current position). I really think it's just a matter of what you're used to. If you work in inches, it takes no time to have a really good sense for what .001" is and that, for example, 1/64" is .015625. It becomes automatic. Neither system really stands out as easier in a meaningful way. That said, I prefer metric.
 
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RE: Metric Or Imperial?

Tue Sep 11, 2012 3:07 am

Quoting bristolflyer (Thread starter):
I was listening to NPR today and there was an American designer talking about designing cell phones, he was talking in mm. What do the big electronics manufacturers use? I feel that describing something as '2mm' is was easier than '3/32'.

From what I've see, stuff on circuit boards themselves are done in metric units, but quite often the enclosures and mounting hardware are done in US. For instance, we still talk of the 19" rack in our lab area. I have noticed that the interior rails of many of the newer racks are adjustable.

Of course NASA and other organizations such as Disney have been caught out due to metric/US conversion errors:

http://www.mentalfloss.com/blogs/archives/68051

http://chemwiki.ucdavis.edu/Analytic...ric%2F%2FEnglish_Conversion_Errors

Quoting Ken777 (Reply 9):
Quoting KFLLCFII (Reply 7):
There are 60 seconds in a minute (time or angle), 60 minutes in an hour/degree, 24 hours in a day, 365 (1/4) days in a year, and 360 degrees in a circle, yet most of the world doesn't seem to have a problem remembering this...

That's because nature isn't metric.

Many computer designs of the 1950s and 1960s were binary based but with 36 bit words. That's because when IBM designed the 701 and 704 (http://en.wikipedia.org/wiki/IBM_704) they decided that 72 bits of precision were needed to do the math that their customers wanted to do. This led to the 6 bit byte, the 36 bit word, and the 72 bit double-word.

The System/360 was named because of 360 degrees in a circle, but interestingly enough it was/is a 32 bit machine.
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rwessel
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RE: Metric Or Imperial?

Tue Sep 11, 2012 3:24 am

Quoting Revelation (Reply 16):
Many computer designs of the 1950s and 1960s were binary based but with 36 bit words. That's because when IBM designed the 701 and 704 (http://en.wikipedia.org/wiki/IBM_704) they decided that 72 bits of precision were needed to do the math that their customers wanted to do. This led to the 6 bit byte, the 36 bit word, and the 72 bit double-word.

The System/360 was named because of 360 degrees in a circle, but interestingly enough it was/is a 32 bit machine.

It was more the single precision (36 bit) floats that were useful. The transition to S/360 with 32 bit singles (which were a bit too short) caused all sorts of grief, and caused many people to recode with doubles (which were more of an exception in earlier times).

And the System/360 ("all around", as in both commercial and scientific applications) had a embedded variant, used in a number of aviation application (including the B-52, F-15 and Space Shuttle), named the "System/4 Pi", which is the number of Steradians in a sphere (more or less the equivalent of 360 degrees for a sphere).
 
Stealthz
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RE: Metric Or Imperial?

Tue Sep 11, 2012 3:27 am

Quoting rwessel (Reply 14):
And folks - the U.S. doesn't use Imperial Units, it uses Standard Units (or more formally, "U.S. Customary Units").

And sinificantly different to imperial measures in some areas.

A US gallon is somwhat smaller than an Imperial one based on a US pint being a touch over 16 fl/oz whereas an Imperial pint is 20 fl/oz.
And ask most Americans how many pounds in a ton??
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RE: Metric Or Imperial?

Tue Sep 11, 2012 3:52 am

Quoting rwessel (Reply 17):

It was more the single precision (36 bit) floats that were useful. The transition to S/360 with 32 bit singles (which were a bit too short) caused all sorts of grief, and caused many people to recode with doubles (which were more of an exception in earlier times).

Interesting. I hadn't thought of this since I tend to work in network and operating system spaces, but I suppose the transition to 64 bit computing has made a lot of these 'dusty deck' programs go really fast.

In particular, the AMD64 mode that Intel has cloned as well also increased the number of general purpose registers as well, so the combination is quite helpful for that type of code.

This presumes a lot of those programs made the transition to IEEE floating point, which from what I understand, can be just as problematic. This caused much grief to a program I worked on when I was an IBMer in the 80s.

Just read that the fastest commercially offered CPU in terms of clock rate is now the latest IBM 360 descendent, running at 5.5 GHz, so if you want your IBM floats you can have them!

Quoting rwessel (Reply 17):
And the System/360 ("all around", as in both commercial and scientific applications) had a embedded variant, used in a number of aviation application (including the B-52, F-15 and Space Shuttle), named the "System/4 Pi", which is the number of Steradians in a sphere (more or less the equivalent of 360 degrees for a sphere).

I had heard of AP-101 in the Space Shuttle context, but I was not aware of the family name System/4 Pi.

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WrenchBender
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RE: Metric Or Imperial?

Tue Sep 11, 2012 3:58 am

Quoting Ken777 (Reply 9):
Imperial. Absolutely no need for the US to change.

I wouldn't mind so much if the US actually used IMPERIAL instead of the bastardised US fluid system. A Gallon is 4.54 L not 3.78 L.

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Ken777
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RE: Metric Or Imperial?

Tue Sep 11, 2012 4:16 am

Quoting WrenchBender (Reply 20):

Quoting Ken777 (Reply 9):
Imperial. Absolutely no need for the US to change.

I wouldn't mind so much if the US actually used IMPERIAL instead of the bastardised US fluid system. A Gallon is 4.54 L not 3.78 L.

You do realize that if the US was to move to the UK Gallon all of our cars would get immediate improvements in milage. My old Caddy might hit 30 MPG on the interstates.  
 
WrenchBender
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RE: Metric Or Imperial?

Tue Sep 11, 2012 4:49 am

Quoting Ken777 (Reply 21):
You do realize that if the US was to move to the UK Gallon all of our cars would get immediate improvements in milage. My old Caddy might hit 30 MPG on the interstates.

Ahhhhh, the new science "How to use statistics to lie like a politician"  

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StarAC17
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RE: Metric Or Imperial?

Tue Sep 11, 2012 4:50 am

Quoting Ken777 (Reply 9):
First, the cost of a conversion is absolutely unnecessary. Every speed limit sign in the US changed just to "be metric"? Stupid.

For 1 dimensional units it is no big deal and a speed limit is because it is a rate there is only the value between km and miles that needs to be considered.

The biggest annoyances are with areas and volumes where converting a square foot to a square meter or a cubic foot to a cubic meter is a big challenge. As an engineer converting something like PSI or PSF to KPa or MPa takes a long time.

The biggest value as an engineer to the metric system is based on values of 10 such as that 1km is 1000m, 1m is 1000mm, 1mm is 1um etc.* It increases productivity.

Whereas 1 mile is 5280 ft, 1yd is 3ft, 1 ft is 12 inches. and there is no easy way to convert values.

*um is the greek symbol used for micro which I have no idea how to enter.
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rwessel
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RE: Metric Or Imperial?

Tue Sep 11, 2012 4:56 am

Quoting Revelation (Reply 19):
In particular, the AMD64 mode that Intel has cloned as well also increased the number of general purpose registers as well, so the combination is quite helpful for that type of code.

64-bit mode has been a mixed bag in terms of performance on most platforms. Obviously it enables more memory, which, for some applications, can be a considerable benefit. But the larger code and longer pointers tend to have a significant (~10%) negative impact on performance, mainly due to increased cache/memory bandwidth pressures. x86-64 is a more complex case - 64 bit code is bulkier due to both the increases in pointer sizes, and increases in code size (lots of REX prefixes lying about), so it tends to be slower, but the extra registers help performance. Most of the time it's about a wash. There's a fairly active effort to define a set of APIs for Linux that uses 32 bit pointers (hence the whole program would have still to fit in 4GB), but it could use the extra regs.

Quoting Revelation (Reply 19):
This presumes a lot of those programs made the transition to IEEE floating point, which from what I understand, can be just as problematic. This caused much grief to a program I worked on when I was an IBMer in the 80s.

S/360 has supported binary IEEE float since the G4 or G5 generation of 9672s in the mid/late nineties. Decimal IEEE float support has been added more recently (so the machines now support three formats).

Binary IEEE float has its issues, but far, far, fewer than old S/360 hex float. Part of the reason IBM did floating hex was to make up for the reduced precision from the transition from 36 to 32 bit floats. Unfortunately this makes the precision effectively wobble, based on what the high digit of the number was, which actually made things worse (in essence, the number of bits of precision wobbles between 21 and 24). The IEEE (single) format has a solid 24 bits (because of the implied leading one bit). These compare to 27 bits in the old 36 bit formats.
 
kl671
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RE: Metric Or Imperial?

Tue Sep 11, 2012 4:58 am

Quoting bristolflyer (Thread starter):
I can see a good reason for using both

Car tire manufacturers apparently share your point of view. Tire widths are measured in millimeters while the diameter is in inches.

I am sure there is a good reason for this but I can't think of one!
 
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RE: Metric Or Imperial?

Tue Sep 11, 2012 5:25 am

Quoting rwessel (Reply 24):
S/360 has supported binary IEEE float since the G4 or G5 generation of 9672s in the mid/late nineties. Decimal IEEE float support has been added more recently (so the machines now support three formats).

Yep, as above, that was probably a decade too late for me. I worked for IBM on a project to put AIX on the mainframe of the time which was ESA. The idea was that it was quite a substantial machine for the time in terms of memory and I/O capacity and throughput (despite its cost) and could be used as application server, file server and/or number cruncher. All three were problematic: a) porting applications to it was not easy, b) it wasn't that stable and reboots took a long time so it was problematic as a file server, and c) the lack of IEEE float drove away the number crunching audience. The meeting where our university partners (who had been given mainframes by IBM) spelled this all out to us was one of the most depressing in my career.

Fast forward 15 or so years and you have SUSE and RHEL on the mainframe, which fixed the application issue (as much as it can be fixed via linux), as well as the stability issues. As you note, all the hardware they support has the IEEE float so that problem went away too. I think one of the early linux ports supported the non-IEEE floats, but shortly decided it wasn't worth the effort. A key enabler was getting GCC to produce decent code for the IBM mainframes, which was no easy task. Google will pull up a few papers on the topic should you be interested in reading about it. I suppose it says something about me that I read those papers?  

Unfortunately for IBM by the time many of these things came together the mainframe's advantage in memory and I/O throughput and capacity weren't there especially on a price/performance basis. However, they are still plugging the product: they had a decent sized booth at the Red Hat Summit I attended in Boston this summer.
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Stealthz
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RE: Metric Or Imperial?

Tue Sep 11, 2012 5:56 am

Quoting kl671 (Reply 25):
I am sure there is a good reason for this but I can't think of one!

Tyre widths were originally in inches, when radial tyres started to replace cross(bias)-ply tyres a way of differentating them was required, measuring the width in mm seemed an easy way to do this, a concept also perhaps driven by the fact the first company to introduce radial automotive tyres was Michelin from France(even though radial tyres were invented by an American in 1915)
In the '70s Dunlop introduced the Denovo, a run flat tyre that required special rims quite different to a normal wheel so they made them in different sizes and the rim diam. was measured in mm again to differentiate them from conventional wheels.

Quoting rwessel (Reply 17):
System/360

Interesting to hear you guys discussing the S/360, my dad was one of the first IBM engineers in Australia trained to service the 360, indeed much of his advanced training was in the US which is how I and the rest of my family spent most of a year living in San Jose CA and Poughkeepsie NY.
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rwessel
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RE: Metric Or Imperial?

Tue Sep 11, 2012 6:00 am

Quoting kl671 (Reply 25):
Car tire manufacturers apparently share your point of view. Tire widths are measured in millimeters while the diameter is in inches.

I am sure there is a good reason for this but I can't think of one!

Because the wheels the tires go on are measured in inches.   

Seriously, though, that's about it. It's an interface between two rather distinct parties, where the bit of commonality is valuable, and the benefits of a change are roughly non-existent.
 
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Scooter01
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RE: Metric Or Imperial?

Tue Sep 11, 2012 6:58 am

Quoting rwessel (Reply 28):
Because the wheels the tires go on are measured in inches.

Actually, in the late 70's/early 80s, the US based Ford Motor Company introduced a metric size rim to be used on the 3rd generation Mustang 5.0 -I guess that means a 5 litre engine.

If I remember correctly, the only tire-manufacturer who produced a tire for it was Michelin with its 220/55R390TRX, where 390 was the rim diameter in mm, a little more than 15". As far as I know they used this wheelsize from the '82 through the '84 model-year -and how many of us remembers the TRX?

Quoting WrenchBender (Reply 20):
I wouldn't mind so much if the US actually used IMPERIAL instead of the bastardised US fluid system. A Gallon is 4.54 L not 3.78 L.

- coldn't agree more...

Scooter01

[Edited 2012-09-11 00:28:26]
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RE: Metric Or Imperial?

Tue Sep 11, 2012 7:07 am

Quoting bristolflyer (Reply 11):
The irony about the imperial system in the construction industry is that a 2" x 4" doesn't actually measure 2" x 4"

That one always makes me laugh. Or cry.

Quoting bristolflyer (Reply 11):
Anyone know what units show on airplane drawings?

Couldn't tell you (I would guess US units on US-produced airplanes). But for my company, which designs/manufactures products that go on space mission, our units are in inches.

Quoting StuckInCA (Reply 15):
I really think it's just a matter of what you're used to.

  

In college, I was used to metric. For problems in US units, I'd sometimes convert the input values to metric, do the calculations, then convert the result back to US. Was just easier to do all the calcs in metric.

Quoting StarAC17 (Reply 23):
The biggest value as an engineer to the metric system is based on values of 10 such as that 1km is 1000m, 1m is 1000mm, 1mm is 1um etc.* It increases productivity.

  
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Stealthz
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RE: Metric Or Imperial?

Tue Sep 11, 2012 7:42 am

Quoting Scooter01 (Reply 29):
If I remember correctly, the only tire-manufacturer who produced a tire for it was Michelin with its 220/55R390TRX, where 390 was the rim diameter in mm, a little more than 15". As far as I know they used this wheelsize from the '82 through the '84 model-year -and how many of us remembers the TRX?

The Michelin TRX was another "radical" tyre design that required a different type of wheel so the best way to diffentiate was to again make it in odd sizes "(390mm I believe the only mass produced size) this prevented the tyres being mountaed on unsuitable rims.
Unlike the Dunlop Denovo, Michelin will still manufacture, to special order,TRX tyres for cars that were fitted with them as std equipment(hate to think what they cahrge for them!)
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Kiwirob
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RE: Metric Or Imperial?

Tue Sep 11, 2012 10:37 am

Quoting Scooter01 (Reply 29):
and how many of us remembers the TRX?

I do, my granddad had a 1980's M635i which used metric tyres, Michellin still makes a batch every so often.

Here's what they make.

http://www.michelin-passion.com/pass...odeRubrique=44&lang=EN&dimension=1

[Edited 2012-09-11 03:42:03]
 
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OA260
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RE: Metric Or Imperial?

Tue Sep 11, 2012 10:49 am

Quoting bristolflyer (Thread starter):
Anyone have preferences, and why?

Having been brought up in England I learnt that way too but also being in Greece during my childhood I learnt both . I actually use both and it comes naturally to me to swap . Just like Miles and KM I can use both without issue and know how to convert without any issue. I dont really have a preference.
 
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Aesma
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RE: Metric Or Imperial?

Tue Sep 11, 2012 1:21 pm

Being in the computer industry imperial units are prevalent (well, inches, really) so I have an idea of what some sizes are, for example I'm using 24" screens right now. But I rarely do the conversion. Watching lots of US movies and TV series in English I also am used to feet and yards, roughly, and when a home is described as 2000 square feet it means 200m² (not really precise I know). I learned the nautical miles and knots as a kid since my father is a sailor.

The problem with the Imperial system is not the units values but that there is no logic in going from one size to the next. I'm very logical since childhood and knowing that 1Kg is the same thing as 10*10*10cm of water is something I found great and helped me a lot at school, since I couldn't be bothered to follow instructions and just solved problems my way.

Quoting fr8mech (Reply 10):
How do they build homes in Metric nations?

Using concrete blocks !
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DeltaMD90
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RE: Metric Or Imperial?

Tue Sep 11, 2012 11:56 pm

I prefer metric but at the end of the day, it's not really a big deal. If we were to change, I think they should start putting the speed limits and temperatures in both units, posted next to each other, and over the years, slowly switch over completely. Because even someone mathematical like me has no concept of C, kg or kms (without slowly converting in my head) which is really needed to be practical. I can go outside and say "it feels like 80F out here" but not really know what 15C would feel like, for example.

But the imperial system has the best unit of measurement, IMO, the foot. I personally find meters too big a lot of times, and cm are often too small. I like the foot
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lewis
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RE: Metric Or Imperial?

Wed Sep 12, 2012 12:06 am

Quoting DeltaMD90 (Reply 35):
But the imperial system has the best unit of measurement, IMO, the foot. I personally find meters too big a lot of times, and cm are often too small. I like the foot

There is the decimetre (dm) but it is rarely used. People tend to use 0.x meters most of the time.
 
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RE: Metric Or Imperial?

Wed Sep 12, 2012 12:10 am

Quoting stealthz (Reply 27):
Interesting to hear you guys discussing the S/360, my dad was one of the first IBM engineers in Australia trained to service the 360, indeed much of his advanced training was in the US which is how I and the rest of my family spent most of a year living in San Jose CA and Poughkeepsie NY.

I've been to Pok a few times for business back in my IBM days, although 'home base' was a half hour or so up the Hudson in Kingston. Pok was where a lot of the CPU design got done in those days, although some was being done in other places too. Also a lot of the mainframe software was done in Pok. SJ was mostly where IBM did storage products, DASD in IBM lingo.
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cmf
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RE: Metric Or Imperial?

Wed Sep 12, 2012 12:24 am

For a very good summary of the problem read Alexander Graham Bell's address to congress. It is more than a 100 years old today but it is just as valid, if not more.

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Few people have any adequate conception of the amount of unnecessary labor involved in the use of our present weights and measures
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DeltaMD90
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RE: Metric Or Imperial?

Wed Sep 12, 2012 12:33 am

Quoting lewis (Reply 36):
There is the decimetre (dm) but it is rarely used. People tend to use 0.x meters most of the time.

Yeah, I know of dm, just thought it wasn't really used. I guess 0.1 meters works. In the end though, barring math and science, people seem to operate fine transferring between imperial US and metric everywhere else. I do wish we'd switch though, I just don't see any compelling reason...
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Ken777
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RE: Metric Or Imperial?

Wed Sep 12, 2012 1:05 am

Quoting StarAC17 (Reply 23):
For 1 dimensional units it is no big deal and a speed limit is because it is a rate there is only the value between km and miles that needs to be considered.

That just brought to mind another cost increase when moving to metric: resale value of cars.

When we moved to PER in 76 we bought a Toyota Corona - actually a pretty nice car.

Traded it in after it hit 100,000 - which caused us to get less on the trade in. That was 100,000 K's, which is just over 62,000 miles. There is, unfortunately, a psychological factor in that 6 digits that you pay for.

Quoting StarAC17 (Reply 23):
Whereas 1 mile is 5280 ft, 1yd is 3ft, 1 ft is 12 inches. and there is no easy way to convert values.

Of course there is - just use your conversion app on your iPhone.  
 
Okie
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RE: Metric Or Imperial?

Wed Sep 12, 2012 2:02 am

Quoting Scooter01 (Reply 29):
Actually, in the late 70's/early 80s, the US based Ford Motor Company introduced a metric size rim to be used on the 3rd generation Mustang 5.0 -I guess that means a 5 litre engine.

I had a friend at the time that had a Ford Thunderbird that had the metric rims.

Quoting stealthz (Reply 31):
Unlike the Dunlop Denovo, Michelin will still manufacture, to special order,TRX tyres for cars that were fitted with them as std equipment(hate to think what they cahrge for them!)

Even back then the friend found it cheaper to replace the rims along with the tires when then tires wore out. The bolt pattern stayed the same for the rims. So at least they left you and escape route.

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RobertNL070
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RE: Metric Or Imperial?

Thu Sep 13, 2012 8:25 pm

Living in mainland Europe of course I use the metric system: kilograms, kilometers (per hour), (milli)litres, degrees Celsius et cetera. However, also in Dutch my car has 17-inch alloy wheels, IIRC my pushbike has 28-inch wheels, my television has a 42-inch screen and I'm sitting behind my 15-inch Mac Book Pro. Screwed up, or what!
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Bongodog1964
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RE: Metric Or Imperial?

Thu Sep 13, 2012 10:03 pm

Quoting fr8mech (Reply 10):
Quoting bristolflyer (Thread starter):
2x4, 2x6 etc and multiples of 4' for sheet materials.

How do they build homes in Metric nations?

We build homes using 100 x 50 studs and we nail sheets of 2240 x 1220 x 12.5 plasterboard to them !!

Good thing we still have imperial on our tape measures as we still place the studs 16" apart which works exactly for a sheet. Metric measurements for them just don't work properly.

Quoting bristolflyer (Reply 11):
That's interesting. The irony about the imperial system in the construction industry is that a 2" x 4" doesn't actually measure 2" x 4" - so converting wouldn't be that much of a chore!

4" x 2" refers to the sawn dimension of the timber. If its purchased sawn it will be that size. If however it is sold planed it will be the same piece of timber passed through a planer which will reduce it by about 1/8" on each dimension
Of course here in the UK thats a 100 x 50 PAR which measures 97 x 47.
 
steex
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RE: Metric Or Imperial?

Fri Sep 14, 2012 1:43 am

Quoting lewis (Reply 8):
"how many inches in a mile?"

In fairness, people wouldn't know this because it's skipping a "step" in between (the foot). It's very rare that you would have a measurement in miles and instead want to have it in inches (or vice versa). I realize the metric system eliminates that problem entirely, but that particular problem doesn't really exist within the standard units either.

Quoting StarAC17 (Reply 23):
The biggest value as an engineer to the metric system is based on values of 10 such as that 1km is 1000m, 1m is 1000mm, 1mm is 1um etc.* It increases productivity.

It all depends on what kind of engineering you do, I'm sure. In my field, all measurements for work in the USA are completed using decimals of feet rather than feet and inches. That makes it no easier or harder than the work I do using the metric system (I have no real preference and am comfortable with either).

Quoting Bongodog1964 (Reply 43):
4" x 2" refers to the sawn dimension of the timber. If its purchased sawn it will be that size. If however it is sold planed it will be the same piece of timber passed through a planer which will reduce it by about 1/8" on each dimension
Of course here in the UK thats a 100 x 50 PAR which measures 97 x 47.

In the USA, the 2" x 4" dimension is the undried, unplaned measurement. Drying and planing both reduce the size of the wood, and the end result is a piece of lumber that loses a full half inch from each dimension. The established standard for a 2x4 is 1.5" x 3.5" for construction.
 
Okie
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RE: Metric Or Imperial?

Fri Sep 14, 2012 3:01 am

Quoting steex (Reply 44):
The established standard for a 2x4 is 1.5" x 3.5" for construction.

That standard was adopted in 1961. Previous it was 1 5/8" (1.625) x 3 5/8" (3.625)
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sccutler
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RE: Metric Or Imperial?

Fri Sep 14, 2012 3:46 am

Quoting okie (Reply 4):

I think Pres Carter started the shift near 40 yrs ago with a goal of being transitioned by 2000. (30yrs)
Now it has been close to 40 years.

Not so much... the metric conversion movement was already in trouble by 1976.

As a kid in elementary school (mid-sixties), I was taught the metric system from the start, with general statement that we'd be converting over around 1970. It was not controversial at that time, the teachers taught it, we learned it. This was in Dallas.

I really cannot grasp why the changeover to metric has ever been objected to; it simply makes better sense.

As a practical matter, though it is not so commonly known, most US manufacturing changed over to metric a while back.
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MadameConcorde
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RE: Metric Or Imperial?

Fri Sep 14, 2012 7:21 am

Those brilliant minds, the scientists, engineers and Space researchers in Russia and the U.S. who had sent the first satellite to Space, the first man to Space and the first man on the Moon did not use imperial measures. Neither those who created and built Concorde.

A genius such as Nikola Tesla did not use Imperial measure, not Marie Curie either.

That for me is a good enough reason to think the whole world should change to the metric system once and for all.

This was the one thing that shocked me when I first travelled across the Atlantic to the U.S. in 1969 to see all measures were imperial and the temperatures in Farenheit degrees rather than centigrades. I thought to myself how can a country so advanced as the U.S. still use the old measures rather than the metric system. Quarts of milk, miles per hour... It just made no sense.

   
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dandaire
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RE: Metric Or Imperial?

Fri Sep 14, 2012 12:41 pm

Quoting B777LRF (Reply 6):
Aviation is another such example, with every single (western built) aircraft in existence is based on inches.

I don't know how you define "Western", maybe you mean American but there are an awful lot of aeroplanes made in France and Germany that are designed and built using the Metric system?

Quoting bristolflyer (Reply 11):
Anyone know what units show on airplane drawings?

At Airbus the drawings use the Metric system. I know when British Aerospace used to make the wings for the A300 aircraft, the drawings used the Imperial system while Aerospatiale in France built the fuselage using the Metric system and guess what, they fitted together ok.
  
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NAV20
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RE: Metric Or Imperial?

Fri Sep 14, 2012 2:39 pm

Like most people, I've had to work with either or both in my time.

On the one hand I think 'Imperial' works far better for larger measurements. In that field it's more 'natural.' An inch approximates to the top joint of your thumb, a foot is - well - a foot  , and a yard is a long pace. Since I was a Chartered Surveyor by profession, 'imperial' made it very easy to 'guess-timate' the area of a piece of land, etc.

And miles are arguably a much more 'sensible' distance for long trips than kilometers (especially the 'nautical mile,' the 'knot,' 2,000 yards, which is of course still used in aviation).

On the other hand, though, I'd be lost without millimetres for the small stuff nowadays. I got thoroughly fed up with messing about with things like 'sixty-fourths of an inch,' and even 'thous' (one thousandth of an inch) in my younger days.

I guess there's still room for both systems to co-exist, really....... 'horses for courses'........

[Edited 2012-09-14 07:45:22]
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