LINES
LINE TYPES
In drafting, different line types are used to convey specific information, distinguish between various elements, and enhance the clarity and readability of drawings. Here are some commonly used line types in drafting:
Continuous/Object Line: This is the standard line type used for visible outlines, boundaries, and visible edges. It is drawn with a solid, unbroken line and represents the visible parts of an object.
Hidden Line: Hidden lines are used to represent features or edges that are not visible in the current view but exist in the object. They are drawn with short dashes evenly spaced along the line and help in understanding the internal features or hidden parts of an object.
Center Line: Center lines are used to indicate the center or symmetry of an object or feature. They are drawn with long and short dashes alternately spaced along the line. Center lines help in aligning and positioning other elements relative to the center of an object.
Extension Line: Extension lines are used in dimensioning to indicate the points to which the dimensions apply. They are drawn as thin, unbroken lines that extend from the object, often terminating with an arrowhead or a dimension line.
Dimension Line: Dimension lines are used to specify the size, distance, or measurement of an object or feature. They are drawn as thin, continuous lines with arrowheads at each end, and they typically include a numerical value indicating the measurement.
Cutting Plane Line: Cutting plane lines are used to indicate the location of a section or cut through an object. They are drawn with long dashes, often with arrowheads, and they help in illustrating the specific view or section being shown.
Phantom Line: Phantom lines represent alternate positions, repeated details, or hypothetical or proposed elements. They are drawn as thin, long dashes, usually with alternating long and short dashes, and they are used to illustrate parts or features that are not present in the actual object but are relevant to the drawing.
Break Line: Break lines are used to shorten or omit long continuous features, such as long edges or repetitive elements, to save space and improve the clarity of the drawing. They are drawn as a zigzag line with freehand or predefined patterns.
Construction Lines: Construction lines are lines that you draw to help you align the other lines that you need to draw. When hand drafting they are faint lines that are easy to erase since they will not be present in the final version of your drawing. In CAD software construction lines are their own line type and the program knows not to print those lines.
These are just a few examples of line types commonly used in drafting. There may be additional line types or variations depending on the specific drafting standards, industry practices, or the purpose of the drawing. The appropriate use of line types helps in accurately representing objects, conveying information, and facilitating the interpretation of technical drawings.
LINE PROBLEMS
1. An exercise for the T square, triangle, and scale. Draw a 4in square and divide it with a horizontal line. Along the lower side and upper half of the left side measure 1/2in spaces with the scale. Draw all horizontal lines with the T square and all vertical lines with the T square and triangle.
2. An interlacement. Draw a 4in square and divide the left and lower sides into seven equal parts. Draw horizontal and vertical lines across the square through these points. Erase the line parts not needed.
3. A street-paving intersection, an exercise in starting and stopping short lines. Draw a 4in square. Draw its diagonals with a 45° triangle. With the scale, lay off 1/2in spaces along the diagonals from their intersection. With a 45° triangle complete the figure.
4. A square pattern. Draw a 4in square and divide its sides into three equal parts. With a 45° triangle, draw diagonal lines connecting these points. Measure 3/8 in on each side of these lines, and finish the pattern as shown in the drawing.
5. An acoustic pattern. Draw two intersecting 45° diagonals 4in long to form a field. With the scale lay off 1/2in spaces from their intersection. The narrow border 3/16in wide, and the second border goes to the end of the diagonals. The length of the border blocks is projected from the corners of the field blocks.
6. Five cards. Visible and hidden lines. Five cards 1.75in by 3 in. are arranged with the bottom card in the center, the other four overlapping each other and placed so that their outside edges form a 4-in. square. Hidden lines indicate edges covered.
7. A Maltese cross. For T square, spacers, and 45° and 30°-60° triangles. Draw a 4in square and a 1 3/8in square. From the corners of the inner square, draw lines to the outer square at 15° and 75°, with the two triangles in combination. Mark points 1/4in inside each line of this outside cross, and complete the figure with triangles in combination.
8. Insignia. Draw the 45° diagonals and the vertical and horizontal center lines of a 4in square. With a compass, draw a 3/4in diameter construction circle, a 2 3/4in circle, and a 3 1/4in circle. Complete the design by adding a square and pointed star as shown.
Once you feel comfortable with drawing different line types and using the different hand drafting tools, the next step is to start with a single view drawing.