![]() ![]() Dimension elementsĭimensioning a drawing also identifies the tolerance (or accuracy) required for each dimension. Once the shape of a part is defined with an orthographic drawing (i.e., in projections), the size information is added in the form of dimensions. However, modern 3D CAD software, which prevails in our days, can offer other line types for the break lines in the computer-based drawings. Sometimes engineers and designers still work on drawings with pencils and rulers. Note that all these break lines were designed for preparing drawings in the old-fashioned manner by using a draft board. The special thick break lines shown for cylindrical and tubular parts are useful when an end view is not shown, but otherwise the thick freehand break line is adequate. Thick freehand lines are used for short breaks The thin line with freehand zig-zags is recommended for long breaks and may be used for solid details or for assemblies containing open space. In end views of circular features the point of intersection of two centre lines should be shown by two intersecting short dashes, except for very small circles, as shown:īreak Line are used to shorten the view of long uniform or tapered sections, or when only a partial view is necessary, and are used on both detail and assembly drawings. It is recommended that these spaces be 0.7 mm or greater. The minimum space between parallel lines should never be less than twice the thickness of the heaviest line. Medium and extra-thick lines should be used only in special cases. In cases where other than shown types of lines are used for special drawings (for example, electrical drawings, pipeline diagrams, or building drawings) the conventions adopted must be clearly indicated by reference to specific standards or by notes on the drawings.įor all views of one piece or assembly to the same scale, the thickness of the lines should be the same. The alphabet of lines assigns specific thickness to each line and it cannot be changed arbitrarily. In general cases it is good enough in practical work. In many textbooks (especially, of the US authors) you will come across the thicknesses of lines: 0.3 mm and 0.6 mm. While preparing drawings you must follow the rules established for the line technique.Įach line should have one of the two thicknesses, thick or thin, and the ratio of the thicknesses must be not less than 2:1. Symmetry lines - as an axis of symmetry of a particular view. There are also lines used in some particular cases:Ĭhain lines - to indicate additional treatment for a surface. ![]() Hidden lines, as you already know, are used to represent features that cannot be seen in the current view.Ĭutting plane lines are used in section drawings to show the locations of cutting planes. Visible lines are used to represent features that can be seen in the current view. Stitch lines - to indicate a sewing or stitching process. Phantom lines are used to represent a movable feature in its different positions. Section lines (hatching) are used in section views to represent surfaces of an object cut by a cutting plane. to mark the centers of circles and the axes of symmetrical parts, such as cylinders and bolts.īreak lines are used to show where an object is broken to save drawing space or reveal interior features.ĭimension and extension lines are used to indicate the sizes of features on a drawing. ![]() The standard line types used in technical drawings are The alphabet of lines and the approximate dimensions used to create different line types, are referred to as linestyles when used with CAD. ![]() The alphabet of lines is a set of standard line types established by the American National Standards Institute (ANSI) for technical drawing. In Graphics Communication practice there is the whole collection of different lines, which are used for drawing purposes. Alphabet of Lines What is the main image, which we are using in all our projects, designs, drawings? ![]()
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