Architectural Graphics-Line Weight, Summaries of Architecture

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ALPHABET OF LINES

Since line is the basis of all drawings, a drafting student must know that every line has a definite meaning, characteristics, use and make-up or construction. These lines are given conventional symbols which are called “alphabet of lines”. Alphabet of lies are the critical component of sketching Lines have different types, thickness and shape has its own meaning. Alphabet of Lines are also known as “Line symbols”.

DIMENSION LINE

“Thin and dark lines use to show the size (span) of an

object with a numeric value. Usually terminates with

arrowheads or tick markings.”

A thin, fine, dark and solid line with arrowheads on both ends terminating in an extension or projection line with a figure which indicates to direction and extent of the length or distance being presented. Note: Arrowheads must be drawn carefully. The length will vary depending upon the size of the drawing. Dimension lines nearest the object should be spaced at least ¼” away. Parallel dimension lines should be at ¼” apart or more if the space is available. The spacing of dimension lines should be uniform throughout the drawing.

CENTRE LINE “Long and short dash lines. Usually indicates center of holes, circles and arcs. Line is thin and dark.” A thin line with long and short dashes drawn alternately which is used to indicate axis of symmetrical objects or features, bolts, circle and path of a motion. The long dashes vary from ¾” or more in length, depending upon the size drawing. The short dashes, should be about 1/16”. Center lines should always start and end with long dashes. EXTENSION LINE PROJECTION OR WITNESS LINE “A light line that extends from the edge or end of a main object line on a drawing, used in conjunction with dimension lines to help determine the dimension of a particular feature.” A thin, dark and solid line that extends from a point on the drawing to which a dimension refers. A gap of about 1/16” should be left where the extension line would join the object line. Extension line extend about 1/8” beyond the outermost arrowhead. Its length varies from ¼” to 1 ½”.

REFERENCE LINE A thin irregular curved line with arrowhead similar to a leader line. Its function is to give an explanatory note of dimension. DITTO or REPEAT LINE A medium weight line which consists of two dashes drawn repeatedly. The two dashes are 1/8 long with 1/32” gap between them with 3/16” space between the short dashes. This line is used to indicate repeated part of the object drawn. SHORT-BREAK LINE “ Thick way line that is used to break the edge of a surface of a part for clarity on a hidden surface.” A visible broken line drawn freehand. It is used to show the fact, that the part of the object is not large. LONG-BREAK LINE “ Long, thin lines that is used to show that the middle section of an object has been removed so it can be drawn on a smaller piece of paper.” A thin line which has breaks. It is used to show that the object has been cut. SECTION CROSS HATCHING LINE A thin line drawn 45° with 1/16” between the lines which is used to indicate that a material has been cut through where some section of a view has been removed. For various metals, different cross hatching lines are used.

CONSTRUCTION LINE

“ Lines that are very light and very thin use to

construct layout work.”

PHANTOM LINE

“Long line followed by two short dashes use to show

alternate position of a moving part.”

The end.