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Thread: history of geometric accuracy

  1. #1

    history of geometric accuracy

    Hello to all members, I am a new member and this is my first post. My name is Mehdi. I have a serious question that may seem a little strange to you. My question is, what is the history of geometric accuracy or dimensional accuracy ? Using only abundant natural materials how would you make a 10cm x 7cm x 4cx cuboid and a 2cm diameter x 15cm long cylinder with dimensional error of 0.1mm maximum? By abundant natural materials I mean: water, animal parts, sand, soil, clay, wood, stones. The material choice for cuboid and cylinder could be anything solid, for example wood or stone. I am asking this question because somehow humans got to today's accuracy. Today the things that are manufactured very precise with errors much less than 0.1mm. I think 0.1mm error is good to begin with. I searched the internet a lot but nothing. it's like we are missing a gap in our history and nobody is interested in that. sorry me if you did not understand the question. anybody ?

    Note: the dimensions that I have chosen for cuboid and cylinder are random, just for example.

  2. #2
    Technical Fellow jboggs's Avatar
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    You would have better luck searching for the history of measuring tools, or units of measure. Accuracy or precision are just the results of the tools. You will find all kinds of interesting things. Try this question - why do ships measure their speed in "knots", and where did that come from? You will also learn that it wasn't until mass production methods were invented that accuracy became important. Until then, it really didn't matter much because every part was custom made to fit another particular part.

  3. #3
    No you did not understand me. I am not talking about standards. Somebody someday may have taken some length of fiber and call it as one meter. My question is:

    Using only abundant natural materials how would you make a10cm x 7cm x 4cx cuboid and a 2cm diameter x 15cm long cylinder with dimensional error of 0.1mm maximum? By abundant natural materials I mean: water, animal parts, sand, soil, clay, wood, stones. The material choice for cuboid and cylinder could be anything solid, for example wood or stone.

    Say for example you also have a strong thin fiber of length 1 meter and with centimeter scales on it, in addition to abundant natural materials. that's the only ready tool you have.
    Last edited by roboticmehdi; 05-02-2013 at 07:27 PM.

  4. #4
    I selected the 0.1mm dimensional error just as an example. the important thing is that the solid pieces that you are going to make must be dimensionally acceptably accurate. o.1mm error is something that you can't feel much or see much. but 1 mm error is something that you can feel when you touch the piece and see. so basicly the pieces must be acceptably accurate.

  5. #5
    Technical Fellow Kelly_Bramble's Avatar
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    Search the internet for "Ancient Greek units of measurement"

  6. #6
    Dear members, , my question is not about units of measurement, please forget about that. The question is ( again ):

    You are on island alone on which there is a lot of water, a lot of sand, a lot of soil, a lot of clay, a lot of trees (wood source) and a lot of different size common stones around. You also have a strong thin fiber of 1 meter long with centimeter scales on it. Your objective is to make a10cm x 7cm x 4cx cuboid and a 2cm diameter x 15cm long cylinder with good dimensional accuracy and precision. How would you do that?

  7. #7
    Lead Engineer Cake of Doom's Avatar
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    Wood (sticks) stuck in sand to make a form with inside measurements being of that required, using magic string to verify. Pack with wet sand allow to set (but not completely dry), remove formwork and hey presto! Task complete!

    Pretty sure Bear Grylls never had to do this to survive though.

  8. #8
    Technical Fellow jboggs's Avatar
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    Maybe that was what you really wanted to know but your first question was:
    "My question is, what is the history of geometric accuracy or dimensional accuracy ?"

    I'm finished doing your obvious homework assignment for you.

  9. #9
    Lead Engineer Cake of Doom's Avatar
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    Maybe it was 2 seperate questions but wikipedia couldn't answer the sticks and string one.

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