Metric System

Discussion in 'Woodturning Discussion Forum' started by Bob Chapman, Jul 14, 2014.

  1. Bill Boehme

    Bill Boehme Administrator Staff Member

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    I speak fluent NASA, so allow me to translate: The root cause had everything to do with mismanagement and poor communications and nothing at all to do metrology (the science of measurement). However, ground based computer modeling of the mission used English to metric conversions so it is the convenient scapegoat.

    The fact that that programming errors existed is not the problem. They always do. Part of the design process is performing V&V testing (validation and verification). The fact that it wasn't done was a management failure of the worst kind. Everything could have been 100% metric or any other units of measure and the same problems would have existed and would not have been discovered.
     
  2. charlie knighton

    charlie knighton

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    its common for written software not completely done by one person, but bits and pieces to be done by many persons, if no v&v, I am surprised they found the water cooler
     
  3. Mark Mandell

    Mark Mandell

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    They weren't trying to find the water cooler. They were trying to find water on Mars. :p
     
  4. Bill Boehme

    Bill Boehme Administrator Staff Member

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    Finding the water cooler was the backup plan. :rolleyes:

    A brief explanation of V&V testing:

    Verification is the process of showing that the software does what you intended for it to do.

    Validation is the process of showing that your intentions were correct.
     
  5. Bob Chapman

    Bob Chapman

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    Thanks guys, it’s been interesting and informative reading your varied responses. It seems that there is the same sort of variation in the US as here. Richard was spot on with his comment about the older members of the British woodturning (or any other) fraternity resisting metric (or SI as Bill correctly comments) units.

    I agree with John that it’s easier to divide 7/16 in half than 27mm, but now try dividing them by three instead. He’s right though that it makes sense to choose whichever units are most convenient. Rules here often have inches (subdivide usually into eighths, sixteenths and sometimes thirty-seconds) on one edge and centimetres, subdivided into millimetres on the other edge. If something happens to be exactly three inches wide (say) then that’s what I’d use, not 76.2mm.

    For the record Britain changed to a decimal currency in 1972 From 240 pennies to the pound we moved to 100 ‘new pennies’ (imaginative name, or what) to the pound. By now the ‘new’ has been dropped and they are just simple pennies again. Surprisingly there was enormous resistance to the new system - again mostly from the elderly (I wasn’t in 1972, but might fall into that category now). We also had a currency unit called a guinea which was one pound and one shilling (1 shilling = 12 old pennies = 1/20 of a pound). Oddly its still sometimes used but now is one pound and five new pence (I/20 of a pound). Incredibly people worried that decimal currency might be too complicated!

    As an ex-schoolteacher I have to disagree with the sentiment behind Charlie’s comment about kids today (‘kids today cannot add, subtract, divide, multiply without some type of devise....I need pencil and paper’). I doubt that American kids are so very different from British kids, and I think he’s mistaken to cast doubts on their abilities. Sure, they might reach for a calculator - and why not - that’s what calculators were invented for. If they didn’t have one I’ve no doubt they’d figure it out. On the whole the majority of teenagers today are just as well educated as most people now in their sixties, but with different knowledge and skills.

    (I can get into a rant about putting down young people. Over here I frequently see signs in shops saying ‘no more than two schoolchildren allowed in at a time’. The implication is that if you can’t watch them they are going to steal everything in sight that’s not bolted down. As a group I refuse to accept that schoolkids are any more inherently dishonest than any other identifiable group of people - there are villains at all ages. I’m waiting to see a sign that says ‘no more than two pensioners (or woodturners, or gardeners, or…) allowed at a time.’ Rant over…phew…deep breaths…calm…calm…Sorry Charlie!)

    It’s been an interesting read. Thanks

    Bob :)
     
  6. Bill Boehme

    Bill Boehme Administrator Staff Member

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    Are there any limitations on school dropouts?

    BTW, we have the same kind of rulers -- inches on one side and cm/mm on the other -- the thing that I am curious about is the length of the ruler used on your side of the pond. Ours are one foot long which shows at least a subtle, if not overt, preference and maybe even a subtle form of brainwashing. :rolleyes:
     
    Last edited: Jul 17, 2014
  7. Bob Chapman

    Bob Chapman

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    That's a good question Bill! It's revealing that I knew without looking that my rules go to 12 inches, but I had to look to check the metric side. I knew it was around 30 centimetres but wasn't sure of the exact markings. It stopped at 30 centimetres. Interestingly (to me, anyway) I have a metric only rule that also goes up to 30 centimetres - in other words it's still a foot long! My two-foot rule obviously goes to 24 inches, but on the other edge it reaches 60.5cm - an odd place to stop.

    I also have a seven inch rule, although it's something of a curiosity since most small rules are six inches long. The first three inches are graduated in 32nds, the fourth inch goes to 64ths and thereafter its graduated in 16ths. The first 10cm on the metric edge are graduated in half-millimetres, the rest in mm. It goes up to 17.7cm. The extra length proves extraordinarily useful.

    My woodturning rarely requires any accurate measuring at all. If pieces have to fit together I make them fit but by trial and error, not by cutting to a predetermined measurement. When I do measure, its always in mm unless some imperial measurement just happens to fit the bill.

    Bob
     
  8. odie

    odie

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    I am a machinist with a company producing medical instruments. The medical industry has converted to the metric system years ago, probably much has to do with an international clientele base. I am now the oldest machinist in our shop, and was here prior to our company changing over to cnc equipment. The old equipment was all based on inches/feet, but all the newer equipment is metric. The younger machinists are very comfortable with metric, and I believe much of their training was based on metric. They are much more computer savvy than I am, so I still run the old equipment, and the younger men run the cnc equipment. I would have trouble doing their jobs, and they don't have much understanding or patience running equipment the old way where all settings are manually done.

    In my own home shop, I'm comfortable with either metric or inches/feet. I think in inches/feet, and generally use that as a "go to" measuring method. This is probably because I grew up using inches/feet. This, IMHO, is where the resistance to changing to metric is.....those who learned using inches. I see this as a long road, but eventually everything will be metric. When all us older persons die off, and all the new tools, and equipment is in metric, the change over will be a natural course of evolution.

    ooc
     
  9. Mark Mandell

    Mark Mandell

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    An' Who'sa Gonna Pay

    fer changing the gazillions of road and speed limit signs to them kilo meter things. eh? Ha! Bet all y'all didn't think about that in yer changin'.

    Dang furiners . . next you know they'll be wantin' us all to be drivin' on the dang wrong side of the road . . .
     
  10. hockenbery

    hockenbery AAW Advisor Staff Member

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    Love my 33x3.5 threads. :)
     
  11. Richard Findley

    Richard Findley

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    Wierdly, we still drive in mph...

    Richard
     
  12. odie

    odie

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    You do?.......that comes as a complete surprise. I thought England was on kilometers.

    ooc
     
  13. Richard Findley

    Richard Findley

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    Once you get onto mainland Europe you get kph, I think Ireland is too but here in good old blighty we are still mph. A land of contradictions I guess you might say ;-)

    Richard
     
  14. Bill Boehme

    Bill Boehme Administrator Staff Member

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    ... and ships and planes use knots everywhere in the world as an approved exception to the SI standard.
     
  15. Bill Boehme

    Bill Boehme Administrator Staff Member

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    BTW, measurement of time is precisely defined by the SI standard in the same way as English units in terms of seconds, minutes, hours, etc. There are no units used for multiples of ten for anything longer than one second. But, decimal relationships are used for units less than a second (microsecond, nanosecond, ...). The reason is essentially the same as it is for the navigation exception allowed by the SI standard. It is because of the way that maps of Earth are defined in terms of degrees of arc and that a day is defined in terms of a solar day as opposed to a full turn in inertial space (referenced to the stars). A nautical mile is approximately one arc minute of latitude -- the relationship is approximate because the earth isn't a perfect sphere, so an arc minute at one latitude is not exactly the same it would be at another.
     
    Last edited: Jul 17, 2014
  16. Steve Worcester

    Steve Worcester Admin Emeritus

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    I actually prefer metric for my work, maybe because even in the US for bicycles it is mostly metric. It's easier to use. When I have to work in fractions I like to go to decimal.
     
    Last edited: Jul 18, 2014
  17. David Hill

    David Hill

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    Bob,
    Yes the U.S. is best word--- "confused" about what measurement system to use. But it is inching (pun intended) toward SI units. I think it has more to do with just being different and a reluctance (read that stubbornness) to change.
    As a former Science Teacher, I had the honor of teaching the metric system many times over and tried to impress the mathematical simplicity of the units and names--but was stymied by other science "educators that insisted teaching conversions thus making it a nightmare for the students. Interesting that all the major corporations are multinational and use the metric units in daily operations. I am proud to say that more than a few of my students have thanked me for making them learn the system.
    I've since changed professions and am happy that medicine is metric for the most part--working on that too on a smaller scale. I'm perfectly comfortable with the SI system in my profession and shop, but do have Imperial tools available.
     
  18. KellyDunn

    KellyDunn

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    I have a car and a truck. One German and one Japanese. Metric tools.One of my micrometers has a button to switch between inches and mm. My oneway lathe is metric yet I had a 1 1/2by8 spindle made for it. You talk cm and I am lost. mm and I think of spanner measurements. Anything more than about 19mm i have to get a ruler. Now I gotta admit the first time a fellow asked me to pass him the metric cresent wrench I had to think about it.
     
  19. john lucas

    john lucas

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    Kelly I have a metric Pipe wrench and slip jaw pliers if you ever need them. If you turn woods from a country that used the metric system should you use a gouge measured in millimeters vs inches.
     
  20. Bill Boehme

    Bill Boehme Administrator Staff Member

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    Most of our turning tools, chucks, and lathes come from other countries -- meaning, of course, that they're metric tools even though they may be marketed in the US with size stated in inches rather than millimeters. And, let's not forget that the figure-8 caliper are also metric. :rolleyes:
     

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