It has previously been mentioned that technical drawings are prepared using only two line thicknesses and if reasonable care is taken a pleasing result can easily be obtained. Drawings invariably need dimensions and notes and if these are added in a careless and haphazard manner, then a very poor overall impression may be given. Remember that technical drawings are the main line of communication between the originator and the user. Between a consultant and his client, the sales manager and his customer, the designer and the manufacturer, a neat well executed technical drawing helps to establish confidence. The professional draughtsman also takes considerable pride in his work and much effort and thought is needed with respect to lettering, and spacing, in order to produce an acceptable drawing of high standard.
The following notes draw attention to small matters of detail which we hope will assist the draughtsman's technique of lettering.
1 Lettering may be vertical or slanted, according to the style which is customarily used by the draughtsman. The aim is to produce clear and unambiguous letters, numbers and symbols.
2 If slanted lettering is used, the slope should be approximately 65°-70° from the horizontal. Legibility is important. The characters should be capable of being produced at reasonable speed and in a repeatable manner. Different styles on the same drawing spoil the overall effect.
3 Use single stroke characters devoid of serifs and embellishments.
4 All strokes should be of consistent density.
5 The spacing round each character is important to ensure that 'filling in' will not occur during reproduction.
6 Lettering should not be underlined since this impairs legibility.
7 On parts lists or where information is tabulated, the letters or numerals should not be allowed to touch the spacing lines.
8 All drawing notes and dimensions should remain legible on reduced size copies and on the screens of microfilm viewers.
9 Capital letters are preferred to lower case letters since they are easier to read on reduced size copies of drawings. Lower case letters are generally used only where they are parts of standard symbols, codes or abbreviations.
10 When producing a manual drawing the draughtsman should take care to select the proper grade of pencil for lettering. The pencil should be sharp, but with a round point which will not injure the surface. Mechanical pencils save time and give consistent results since no resharpening is necessary.
11 Typewritten, stencilled or letters using the 'Letraset' adhesive letter system may be used since these provide uniformity and a high degree of legibility.
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