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Line Types
Line Types
Dimensioning
Dimensioning
It is very important to add dimensions (measurements) when drawing accurate orthographic or working drawings. An orthographic drawing is usually the last drawing before manufacture and so dimensions must be clearly presented and understood. Dimensions can also be applied to simple sketches and designs as they help anyone looking at these to understand the overall size or scale. However, dimensions are usually drawn in a particular way and will always be measured in millimetres so you do not have to show units. Some examples are shown below.
Horizontal and Vertical Dimensioning
Horizontal - Leader lines must not touch model. Dimension sizes always positioned above dimension line and in centre.
Vertical - Leader lines must not touch model. Dimension sizes always positioned on the left hand side of the dimension line and in centre.
Diameter and Radius
Full circles should always be dimensioned to show their diameter.
Curves or Arcs should always be dimensioned to show their radius.
Orthographic
Orthographic
Orthographic drawing is a 2D way of drawing a three dimensional object. Normally the object is drawn as three separate, related views - Elevation, End Elevation and Plan View.
The example below shows a simple shaped block, with a hole drilled all the way through.
The front view, is a drawing of the block, as if you are looking directly at the front of the object.
The side view, is a drawing of the block, when it has been rotated so that one of its sides is now directly in view.
The plan view, is a ‘birds eye’ view, from above.
Dotted lines represent ‘hidden detail’. In this case they represent the hole, through the block/object.
1 Point Perspective
1 Point Perspective
Perspective drawing is a good style to use when drawing in 3D. There are different styles including single point and two point perspective. The basic example to the right shows how to construct a simple single point perspective drawing of a cube. Using the same skills more complex drawings/designs can be drawn, after a little practice.
Isometric
Isometric
Isometric drawing is way of presenting designs/drawings in three dimensions. The example to the right has been drawn with a 30 degree set square. Designs are always drawn at 30 degrees in isometric projection. It is vital that drawing equipment such as T-squares and 30/60 degree set squares are used carefully. The drawing paper should be clip securely to a drawing board.
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