Introduction to Drafting and Design Alphabet of Lines Introduction to Drafting and Design In this presentation, we are going to learn about the different lines that are used in a drawing. The list of different lines is known as the alphabet of lines

What is the Alphabet of Lines? Developed by the American Society of Mechanical Engineers (ASME). The Alphabet of Lines is used to make a drawing neater and clearer to understand. Different lines represent different aspects of a drawing. So what is the Alphabet of Lines? The alphabet of lines was developed by the American Society of Mechanical Engineers and is used by all drafters and engineers today. It is used to make a drawing neater and clearer to understand. Different lines represent different aspects of a drawing.

So what are these lines? Construction Lines Visible/Object Lines Hidden Lines Center Lines Dimension Lines Extension Lines Phantom Lines Long Break Lines Short Break Lines Cutting-plane Lines Section Lines Chain Lines Leaders Symmetry Lines Border Lines So what are these lines that are considered the Alphabet of Lines? Construction lines Visible/object lines Hidden lines Center lines Dimension lines Extension lines Phantom lines Long break lines Short break lines Cutting-plane lines Section lines Chain lines Leaders Symmetry lines Border lines

Construction Lines Used to initially lay out a drawings. Used for guidelines for lettering. Drawn very light and thin so that they are barely visible. Construction lines Used to initially lay out a drawing Used for guidelines for lettering Drawn very light and thin so that they are barely visible They should be drawn so light that they don’t have to be erased once the drawing is complete.

Visible/Object Lines Used to represent the visible edges of an object. Should be the most prominent on the drawing. Drawn thick and dark. These are thicker than construction lines. Visible/object lines Used to represent the visible edges of an object. Should be the most prominent on the drawing Drawn thick and dark These are thicker than construction lines.

Hidden Lines Used to represent edges, surfaces or corners of an object hidden from view. Drawn as thin, dark dashed lines. Spacing can vary slightly. Only the most important hidden parts are shown on the drawing to keep the drawings from becoming cluttered. Hidden Lines Used to represent edges, surfaces or corners of an object hidden from view. Drawn as thin, dark dashed lines Spacing can vary slightly Only the most important hidden parts are shown on the drawing to keep the drawings from becoming cluttered.

Center Lines Used to show the center of circles and arcs. Drawn as thin lines. Drawn using two long dashes and a shorter dash. To show the center of a round object, two centerlines are used so that the short dashes cross in the center. Center lines Used to show the center of circles and arcs Drawn as thin lines Drawn using two long dashes and a shorter dash To show the center of a round object, two centerlines are used so that the short dashes cross in the center.

Dimension Lines Used for dimensioning and notes. Drawn as thin lines. Drawn with arrowheads on each end and placed between extension lines. The dimension is lettered above the dimension line approximately half way between the two extension lines. Dimension lines Used for dimensioning and notes Drawn as thin lines Drawn with arrowheads on each end and placed between extension lines The dimension in lettered above the dimension line approximately half way between the two extension lines.

Extension Lines Used to extend dimensions from the related objects. Drawn as thin lines. Drawn with a short space between the object and line. Extend about 3 mm beyond the dimension line. Extension lines Used to extend dimensions from the related objects Drawn as thin lines Drawn with a short space between the object and line. Extend about 3 mm beyond the dimension line

Phantom Lines Used to show objects that are not hidden but they are simply not in view. Also used to indicate alternate positions of moving parts, lines of motion, adjacent parts and repetitive details. Drawn as thin, dark lines. Phantom lines Used to show objects that are not hidden but they are simply not in view Also used to indicate alternate positions of moving parts, lines of motion, adjacent parts and repetitive details Drawn as thin, dark lines

Long Break Lines Used to indicate parts of the object has been removed. Used when it is desirable to shorten the view of a long part. Long break lines are drawn thin with freehand “zigzags”. Long break lines used to indicate parts of the object has been removed used when it is desirable to shorten the view of a long part long break lines are drawn thin with freehand “zigzags”

Short Break Lines Used to indicate parts of the object has been removed. Used when it is desirable to shorten the view of a long part. Short break lines are drawn thick and with freehand wavy lines. Short break lines Used to indicate parts of the object has been removed Used when it is desirable to shorten the view of a long part Short break lines are drawn thick and with freehand wavy lines

Cutting-plane Lines Used to indicate the plane through which a cut was made. A cutting plane line is usually a heavy line with long dashes with arrowheads at both ends of the line. The arrowheads point to the surface to be viewed. Cutting-plane lines Used to indicate the plane through which a cut was made A cutting plane line is usually a heavy line with long dashes with arrowheads at both ends of the line The arrowheads point to the surface to be viewed

Section Lines Used to indicate the surface in the section view imagined to have been cut along the cutting plane line. Thin “cross hatching” lines drawn at a 45° angle. Section lines Used to indicate the surface in the section view imagined to have been cut along the cutting plane line Thin “cross hatching” lines drawn at a 45° angle

Chain Lines Used to indicate an area or portion of a surface that is to receive special treatment. Represented by a long dash followed by a short dash followed by a long dash. Chain lines Used to indicate an area or portion of a surface that is to receive special treatment Represented by a long dash followed by a short dash followed by a long dash

Leaders Used to point to notes or dimensions. Drawn as thin lines. Consist of an arrowhead and angled line connected to a surface. Arrowheads touch the object lines while the dot rests on a surface. Leaders Used to point to notes or dimensions Drawn as thin lines Consist of an arrowhead (or dot) and angled line connected to a surface Arrowheads touch the object lines while the dot rests on a surface

Symmetry Lines Used when partial views of symmetrical parts are drawn. It is a center line with two thick short parallel lines drawn at right angles to it at both ends. Symmetry lines Used when partial views of symmetrical parts are drawn It is a center line with two thick short parallel lines drawn at right angles to it at both ends

Border Lines Used to outline the entire drawing. They are a continuous thick line on the outer rim of the paper. Border lines Used to outline the entire drawing They are a continuous thick line on the outer rim of the paper

Let’s look again… Let’s take a look again at the picture that appeared at the beginning of this presentation

Hierarchy of Lines If lines happen to overlap, then there is a hierarchy to which the lines show up. The hierarchy of lines is as follows: Object or visible line Hidden line Cutting Plane line Center line Break line Dimension and extension lines Sectioning lines Hierarchy of Lines If lines happen to overlap, then there is a hierarchy to which the lines show up The hierarchy of lines is as follows: Object or visible line Hidden line Cutting plane line Center line Break line Dimension and extension lines Section lines