Scales, ContinuedTypes of scalesUsing the scaleIndicating scaleMECHANICAL ENGINEER’S SCALE: Mechanical engineer’s scales areused for small machine parts not less than one-eighth scale. These scales aredouble-numbered.To use any scale, lay the scale on a surface parallel to a line. Use a sharppencil to mark all measurements before moving the scale. Your moving thescale for each measurement increases the likelihood of a cumulative error.Indicate the measurements with a sharp pencil or pin prick. Do not drawagainst 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. —Measuringincrements on a triangularscale.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 threeways to indicate the scale on a drawing are the factional method, theequation method, and the graphic method.FRACTIONAL METHOD: The tractional method is indicated by a fractionor ratio. The drawing unit is the numerator and the object is thedenominator.EQUATION METHOD: Scale indicated by feet and inches is the equationmethod of indicating scale. Feet are followed by a single apostrophe (’) andinches are shown with a double apostrophe (“).Continued on next page2-54
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