Using the Scale Ruler

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Using the Scale Ruler

• What is Scale?
• What are all these tiny lines anyway?

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Layout of the scale rule

• Typical scale rule has 10 different scales on it,
  plus a standard ruler (full scale)
• Two scales will share a side
• This is what often causes confusion, as the two
  scales will overlap

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Reading the Scale Rule

• Determine what scale the drawing is drawn in. 
• You can usually find this information in the
  title block area of the drawing in the lower
  right corner or along the right hand edge of the
  page.
• Find the corresponding scale on the scale ruler. 
  
• Note that on the common triangular scale rules
  each edge has two different scales printed on
  it.  Make sure you are reading the correct one.
• Starting at the mark labeled "0" follow the line
  along. 
• If the line ends exactly on an even foot
  increment, then that is how many feet the line
  represents.
• If the line falls in-between two foot increment
  marks slide the ruler along until the end of the
  line is even with the smaller of the two foot
  marks it falls between.  You will now notice that
  the opposite end of the line extends past the "0"
  mark.  Those small increments are inches and
  fractions of an inch

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Reading the Scale Rule

• Rules of thumb
• For the larger of the two scales, count EVERY
  OTHER line for feet. For the smaller count EVERY
  line as a foot.
• Example on the side with 1 and ½.
• If you are measuring in 1 scale, skip the 20 and
  count the 1, skip the 18 and count the 2
• If you are measuring in ½ scale, count the 10 as
  one foot, the 2 as two feet, the 9 as three feet

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Reading the Scale Rule

• The values for the increments in the inches area
  (the really small lines at either end of the
  scale rule) for our typical scales are as follows
• 3 scale each increment represents 1/8
• 1 scale each increment represents ¼
• ½ scale each increment represents ½ (note
  that this is just a coincidence)
• ¼ scale each increment represents 1

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Reading the Scale Rule

• You can clearly see that as the scale gets
  larger, the smaller the increments you can see
  and hence more detail .