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Friday, December 20, 2013

Draftsman Tools

Draftsman Tools

Drafting for engineering and architectural purposes has a long history. Until the advent of computers for design and drafting, the tools have remained the same over time. Their function was to draw straight lines, curves, angles, circles and ellipses. The computer also draws these forms, but without the traditional drafting equipment. Until computers came into use, these tools drew all engineering achievements.

Tables, Vellum, Pens and Pencils

    A smooth table to tape drawing vellum or Mylar on is a basic item. Drafting linoleum that is smooth and firm covers the top of a drafting table. Pencils and ink pens are the most common instruments used to draw the lines. Pens and pencils have different widths, and the pencils different hardness. Wooden drafting pencils and lead holders that hold a piece of lead are hand sharpened to variable widths.

Straight Lines and Angles

    Use a T-square to draw a straight horizontal line.
    Use a T-square to draw a straight horizontal line.

    The instruments to draw straight horizontal and vertical lines are a T-square and triangles. The T-square draws straight horizontal lines. A triangle of 90 degrees is to draw perpendicular lines. These come in two formats. One is 45/90 degrees and the other is 30/60/90 degrees. These allow 30, 45 and 60-degree lines. A protractor allows drawing other angles. An alternative is a drafting machine with a protractor. This has vertical and horizontal rulers with an adjustable hub to set angles.

Circles, Ellipses and Curves

    Drafting templates create shapes on your plans.
    Drafting templates create shapes on your plans.

    Compasses draw circles and ellipses. It is a two-legged adjustable divider with lead at the end of one leg and a point at the other. They function the same as the compass used in math and geometry. Plastic templates also draw circles and ellipses. Templates are thin plastic sheets that have various sizes of circles and ellipses. French curves are plastic tools with a variety of variable curves.

Scales

    Use French curves for irregular curves.
    Use French curves for irregular curves.

    Scales are precision tools for measurement. They commonly divided into inch and metric measurements. Some are flat, with the possibility of different scales on the two sides. Triangle scales are three-sided, with different scales and ratios on the six faces. Mechanical engineering, civil engineering, architectural and metric disciplines have versions of scales. They all have basic inch or metric scales with other common scales on other available faces.

Changes

    Erasers of different types and hardness make changes to vellum and Mylar drawings. These erasers are for hand or electric use. An electric eraser looks like a pencil and fits into an electric holder that rotates the eraser to remove lines. An eraser shield is a thin metal plate with various cutouts to allow erasing only parts of a line.

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