Engineering Drawing Layout and Lettering

Layout of a drawing sheet 
Every drawing sheet is to follow a particular layout.  As a standard practice sufficient margins are to be provided on all sides of the drawing sheet.  The drawing sheet should have drawing space and title page.  A typical layout of a drawing sheet is shown in the figure below:

• Borders – A minimum of 10 mm space left all around in between  the trimmed edges of the sheet.
• Filing margin – Minimum 20 mm space left on the left hand side with border included. This provided for taking perforations .
• Grid reference system – This is provided on all sizes of industrial drawing sheets for easy location of drawing within the frame.  The length and the width of the frames are divided into even number of divisions and labeled using numerals or capital letters.  Number of divisions for a particular sheet depends on complexity of the drawing. The grids along the horizontal edges  are labeled in numerals where as grids  along vertical edges are labeled using capital letters. The length of each grids can be between 25 mm and 75 mm.  Numbering and lettering start from the corner of the sheet opposite to the title box and are repeated on the opposite sides. they are written upright. Repetition of letters or numbers like AA, BB, etc., if they exceed that of the alphabets. For first year engineering students grid references need not be followed.
• Title box – An important feature on every drawing sheet.  This  is located at the bottom right hand corner of every sheet and provides the technical and administrative details of the drawing.  The title box is divided into two zones
• a.    Identification zone : In this zone the details like the identification number or part number, Title of the drawing, legal owner of the drawing, etc. are to be mentioned.
• b.    Additional information zone : Here indicative items lime symbols indicting the system of projection,  scale used, etc., the technical items lime method of surface texture, tolerances, etc., and other administrative items are  to be mentioned.

Layout of the title box recommended for Engineering Drawing Course
The title box shown in figure 2  can be used for  the engineering Drawing Course.

Lettering 
Lettering is used for writing of titles, sub-titles, dimensions, scales and other details on a drawing. Typical lettering features  used for engineering drawing is shown in figure 3. The following rules are to be followed in lettering. The letter  sizes generally recommended for various items are shown in Table 1.

•  Essential features of lettering – legibility, uniformity, ease, rapidity, and suitability for microfilming/photocopying/any other photographic processes
•  No ornamental and embellishing style of letter
•  Plain letters and numerals which are clearly distinguishable from each other in order to avoid any confusion even in case of slight mutilations

         The Indian standard followed for lettering is  BIS: 9609

•     Single stroke lettering for use in engineering drawing – width of the stem of the letters and numerals will be uniformly thick equal to thickness of lines produced by the tip of the pencil.
• ·      Single stroke does not mean – entire letter written without lifting the pencil/pen

       Lettering types generally used for creating a drawing are

• ·       Lettering A – Height of the capital letter is divided into 14 equal parts
• ·        Lettering B – Height of the capital letter is divided into 10 equal parts

Table 2  and Table 3 indicates the specifications for Type A and Type B letters.

Heights of Letters and Numerals

1.    Height of the capital letters is equal to the height of the numerals used in dimensioning

2.    Height of letters and numerals – different for different purposes

Table 1 The letter  sizes recommended for various items

How to begin your drawing?
To start with the preparation of a drawing the procedure mentioned below may be followed:

• Clean the drawing board and all the drawing instruments using duster.
•    Fix the drawing sheet on the drawing board.
• Fix the mini-drafter in a convenient position.
• Draw border lines using HB pencil.
• Complete the title box using HB pencil
• Plan spacing of drawings b/n two problems/views beforehand.

·        Never sharpen pencils over drawing.

• ·        Clean pencil point with a soft cloth after sharpening.
  ·        Keep drawing instruments clean.
  ·        Rest hands on drawing instruments as much as possible – to avoid smearing the graphite on the drawing.
  ·        When darkening lines – try to work from the top of the drawing to the bottom, and from left to the right across the drawing.
  ·        Use brush to remove eraser particles. Never use hands.
  ·        Always use appropriate drawing pencils.

·