Scales, Continued
Types of scales
Using the scale
Indicating scale
MECHANICAL ENGINEER’S SCALE: Mechanical engineer’s scales are
used for small machine parts not less than one-eighth scale. These scales are
double-numbered.
To use any scale, lay the scale on a surface parallel to a line. Use a sharp
pencil to mark all measurements before moving the scale. Your moving the
scale for each measurement increases the likelihood of a cumulative error.
Indicate the measurements with a sharp pencil or pin prick. Do not draw
against the machined increments of the scale or use it as a cutting edge.
Figure 2-64 illustrates the use of a pinpoint to indicate measurements.
Figure 2-64. —Measuring
increments on a triangular
scale.
Indicating scale on a drawing expresses the ratio of the item to the drawing.
It lends perspective to the viewer by providing a reference point. The three
ways to indicate the scale on a drawing are the factional method, the
equation method, and the graphic method.
FRACTIONAL METHOD: The tractional method is indicated by a fraction
or ratio. The drawing unit is the numerator and the object is the
denominator.
EQUATION METHOD: Scale indicated by feet and inches is the equation
method of indicating scale. Feet are followed by a single apostrophe (’) and
inches are shown with a double apostrophe (“).
Continued on next page
2-54
