SCALE
The objective of a technical drawing is to provide sufficient information for others to replicate the depicted object accurately. This entails including specific details presented in various ways. Firstly, drawings can be to scale, meaning that measurements on the drawing correspond accurately to those of the actual object being produced. The scale factor, indicating the relationship between the drawing and the real object, is typically mentioned in the title block. For instance, a 1:1 scale implies a direct correlation, while a 1:4 scale means the drawing is four times smaller than the actual object, and vice versa. In scaled drawings, precise measurements or dimensions may not be necessary on the drawing itself; the focus is primarily on the accuracy of the representation.
Alternatively, dimensioning is another method used to convey information about the drawing. Dimensions are explicit measurements indicating the size of various aspects of the depicted object. While different unit types can be employed, it's crucial to note if the drawing is not to scale and relies solely on dimensions to communicate design specifications. This notation, typically "NTS" (not to scale), ensures clarity for viewers interpreting the drawing.
HOW TO READ A SCALE
Familiarize yourself with the engineering scale tool: The engineering scale tool typically consists of a transparent ruler or straightedge with calibrated scales on both sides. Each scale represents a different unit of measurement and scale ratio.
Determine the appropriate scale: Identify the scale ratio specified on the drawing. Look for a scale on the engineering scale tool that matches the scale ratio mentioned in the drawing's title block or notes.
Place the scale tool on the drawing: Align the engineering scale tool along the line or dimension you want to measure. Ensure that one of the calibrated scales on the tool matches the scale ratio of the drawing.
Read the measurement: Locate the tick mark or point on the scale that corresponds to the desired dimension. Read the measurement value directly across from that tick mark. The measurement should be read in the appropriate units indicated on the scale (e.g., inches, centimeters).
Account for subdivisions: Similar to using an engineering scale ruler, the engineering scale tool may have subdivisions within each main unit of measurement. If the desired dimension falls between two tick marks, estimate the fraction or subdivision by visually dividing the space between the tick marks.
Apply the scale ratio: Multiply the measurement obtained from the engineering scale tool by the scale ratio indicated on the drawing to determine the actual distance in reality. Make sure you use the correct units of measurement (metric or imperial) for the drawing and scale ratio.
Always exercise care and precision while using the engineering scale tool, ensuring proper alignment and accurate reading of measurements.
Practice
Rotate the scale to the corresponding scale of the drawing you are measuring or trying to produce.
Place the end of line at a whole number of the direction the scale is in.
The remaining length of line will go past the zero on the scale and will result in inches of a foot.
1.
2.
3.
Answers: 1) 16'-2" 2) 12'-6" 3) 1'-3"