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Scale 1:25 or 1:75 why scale ruler first reading is 0.5m and 1m respectively ?

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  • Scale 1:25 or 1:75 why scale ruler first reading is 0.5m and 1m respectively ?

    https://onlineconversion.vbulletin.n...1-250-to-1-200

    Dear folks

    Yes I do understand scale ration 1:25 means 1 unit on a map equal to 25 units on a real and scale ration 1:75 means 1 unit on a map equal to 75 units on real

    Question my Kent tri scale ruler showing first number for ratio 1:25 as 0.5 m (i.e 50 cm, 500 mm) while first reading for ratio 1:75 as 1 m (100 cm, 1000mm) ?

    My confusion for the ratio 1:25 ruler has 25 small tiny line between 0 and next reading means 25 units right ?? if I multiply 25*25 = 625 why scale reads it as 500 mm or 0.5 m????

    Same thing for the ratio 1:75 ruler has 20 small tiny lines between 0 and next reading means 20 units right ?? if I multiply 20*75 = 1500 why do I have 1000 mm or 1 m ????

    Thanks
    Last edited by zillah; 08-20-2017, 09:17 PM.

  • #2
    I can't find a detailed image of your specific scale. However, you have to interpret the minor lines with respect to the major lines. Most scales for which I could find good images show the units of the numbered lines either at the opposite end from the numeric scale or at one or more points along the ruled length (normally meters on a metric svale). At 1:25, there should be 40 mm between the zero and the "1" marking (about 13.3 mm on the 1:75 scale). You will have to count the minor and intermediate markings to determine how finely they divide that 1 m.

    On another brand that I looked at, the first numbered mark on the 1:25 scale was 0.5 m and that section was subdivided into 25 minor and medium marks, each representing 0.02 m on the project. On the 1:75 scale, the first numbered mark was 1 m, subdivided into 20 marks each representing 0.05 m. Both the same as your scale.

    Always focus on the numbered marks first, then determine how the minor marks subdivide the numbered marks.

    Comment


    • #3
      Thanks John

      1:25 showing 25 subdivisions (tiny lines) right ? if we times 25 tiny lines x 25 mm = 625 mm not 500 mm
      http://imgur.com/a/CmVFe

      While for 1:75 showing 20 subdivisions (tiny lines) right ?
      http://imgur.com/a/42AyT
      Last edited by zillah; 08-21-2017, 04:05 AM.

      Comment


      • #4
        Originally posted by zillah View Post
        Thanks John

        1:25 showing 25 subdivisions (tiny lines) right ? if we times 25 tiny lines x 25 mm = 625 mm not 500 mm
        http://imgur.com/a/CmVFe

        While for 1:75 showing 20 subdivisions (tiny lines) right ?
        http://imgur.com/a/42AyT
        The ruler is designed to be direct reading to the project. Focus on the numbered marks and what they mean on project scale. The minor marks simply subdivide that major numbered mark. On the rule I looked at (not same brand as yours), there were 25 minor marks, each representing 0.02 m (20 mm). 25 x 0.02 m = 0.5 m (the first numbered mark)

        The 1:25 does not mean each minor division is 25 mm. It means any distance on the project is represented by 1/25 that distance on the drawing. The numbered 0.5 m mark should be 20 mm from the origin.


        Comment


        • #5
          On the rule I looked at (not same brand as yours), there were 25 minor marks, each representing 0.02 m (20 mm). 25 x 0.02 m = 0.5 m (the first numbered mark)
          For sure and with no doubt I agree.

          The 1:25 does not mean each minor division is 25 mm. It means any distance on the project is represented by 1/25 that distance on the drawing.
          I feel bold phrase from your above quote contracts with many online sources as below

          http://www.archaeologica.org/Drawing%20to%20Scale.htm
          Here they consider tiny division (i.e mm) and each tiny line on ruler is 200 mm on real
          Let's start with the scale at the top labeled 1:200. Imagine that you lay this scale on your piece of paper and draw a line from the 0 to the number 5. You just drew a line that is 5 meters long at 1:200,meaning that if you measured this line on the paper, every millimeter would be equal to 200 millimeters on the original object you are drawing.


          https://www.dlsweb.rmit.edu.au/toolb...l/04scales.htm
          Here same as above they consider tiny division and they multiply them by the used scale to find real dimension on real
          The photo below shows measuring diagonally with a ruler from a wall corner to a wall corner on a site plan.The measurement on the ruler is 78 millimetres ( 0.078 metres). The scale is 1:200. Therefore the actual size would be 15.6 metres (0.078m X 200).
          Plesae correct me if I am wrong

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          • #6
            Originally posted by zillah View Post
            For sure and with no doubt I agree.


            I feel bold phrase from your above quote contracts with many online sources as below

            http://www.archaeologica.org/Drawing%20to%20Scale.htm
            Here they consider tiny division (i.e mm) and each tiny line on ruler is 200 mm on real




            https://www.dlsweb.rmit.edu.au/toolb...l/04scales.htm
            Here same as above they consider tiny division and they multiply them by the used scale to find real dimension on real


            Plesae correct me if I am wrong
            Please measure the "tiny lines" with a "true scale" (1:1) ruler. They aren't a millimeter apart. They subdivide the major marks. You don't need a scale ruler at all. You can use a regular ruler and multiply every millimeter by 25 if you wish, but you have to do a lot of math. I would only do this for a scale where I do not have the correct scale ruler. Tghe belief that the tiny lines are 1 mm apart is what leads to your initial dilemma. The 0.5 m mark should be 20 mm (true scale) from the origin and each of the 25 tiny lines is 0.8 mm apart, and represents 0.8 mm x 25 = 20 mm.

            Comment


            • #7
              10000000000000000000000000000000000000000000 thanks John
              They aren't a millimeter apart
              Agree I have should said measurement unit not millimeter

              The belief that the tiny lines are 1 mm apart is what leads to your initial dilemma.
              Yeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee eeeeeeeeeeeeeee

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