Technical Drawing Alphabet of Lines

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Technical Drawing Alphabet of Lines

Technical drawing is a universal language of industry and is governed by the American National Standards Institute (ANSI). Each line on a drawing has a definite meaning and is drawn in a certain way.
There are three distinct thicknesses of lines:
Widths are generally of ratio of 2 to 1.
.3mm minimum for thin lines
.6mm minimum for thick lines

Thick
Medium
Thin

All lines should be clean cut, dark, and uniform throughout the drawing (with the exception of construction lines) and properly spaced
Thick:
.6mm
F or H pencil

Border lines
Visible lines (Object Lines)

Should be the outstanding feature on the drawing
Outline of the object
Shows visible edges and surfaces
Thick
dark

Cutting plane lines

Locates the plane of projection for section or cut-away views

Short-break lines

Used to show a break on a small object
Line thickness is .3mm

Medium:

Hidden lines

Thin
Dark
1/8” dashes
1/16 in between the dashes

Thin:
.3mm
2H pencil

Long-break lines

Used to show a break on an Overly large object
Line thickness is .5mm

Section lines

Shows solid areas of an object

Center lines

Should be as dark as the visible or hidden lines
Used to represent an axis of symmetry
Always used for circles and arcs to locate their centers
Thin
dark

Dimension lines

A line or lines that extend from an object to help better portray a dimension by eliminating clutter and crowding next to the object being dimensioned

Extension lines

A line or lines that extend from an object to help better portray a dimension by eliminating clutter and crowding next to the object being dimensioned

Phantom lines

All lines except construction lines should be dense black so that they will be clearly reproduced by blueprinting or copying. The contrast in line type should come from the thickness, not the darkness.
Construction lines are extremely light, so light that they can not be seen when the paper is held at arm’s length. Use a hard pencil, such as 4H. These lines are used to “block in” or construct a drawing before the lines are made heavy. Construction lines are also used as guide lines for lettering.
Hidden lines are dashed lines that represent an edge or surface that cannot be seen in the view.

Source : http://www.oswego.edu/~waite/OUP-TechnicalDrawingByRoberts.DOC

Web site link to visit: http://www.oswego.edu

Google key word : Technical Drawing Alphabet of Lines file type : doc

Author : Original Writing Team (1986): David Kelsey, SUNY Oswego Dennis Kroon, Massapequa UFSD Tony Mangone, Hauppauge UFSD Raffaele Palumbo, West Seneca CSD Stuart Soman, West Hempstead UFSD Ed VanAmerongen, South Colonie CSD

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