Engineering Drawing | Scale | Tips For Dimensioning

Introduction to Engineering Drawing

A technical person can use the graphic language
as powerful means of communication with others for conveying
ideas on technical matters. an engineer should posses good
knowledge, not only in preparing a correct drawing but also
to read the drawing correctly.
technical drawing architectural example
Classification of
1) Machine Drawing
These drawings are about machine parts.
machine drawing example

2) Production Drawing
A production drawing, also referred to as working
drawing, should furnish all the dimensions, limits and
special finishing processes such as heat treatment, honing,
lapping, surface finish 
etc., to guide the
craftsman on the shop floor in producing the

3) Part DrawingComponent
or part drawing is a detailed drawing of a component to
facilitate its manufacture.

4) Assembly DrawingDetail
drawing of assembly.

Subtypes are: Design Assembly Drawing, Detailed
Assembly Drawing, Sub-
Drawing, and Installation Assembly Drawing.
5) Machine Shop Drawing: A
machine shop drawing frequently gives only the information
necessary for machining.
6) Patent Drawing:  This drawing is
drawn in the patent report with details and assembly of a
parts. In this drawing numbers like 1,2,3,4 are given to Sub


Most of engineering Students get confused about
scale reduction and enlargement. Scale is the ratio of the
linear dimension of an element of an object as represented in
the drawing, to the real linear dimension of the same element
of the object itself. Wherever possible, it is desirable to
make full size drawings, so as to represent true shapes and
sizes. If this is not practicable, the largest possible scale
should be used. While drawing very small objects, such as
watch components and other similar objects, it is advisable
to use enlarging scales

How to Specify a Scale:

The complete designation of a scale should consist of
the word Scale, followed by the indication
SCALE 1: 1 for full size,
SCALE ×: 1 for enlarged scales,
SCALE 1: × for reduced scales.
The designation of the scale used on the drawing
should be shown in the title block.
Recommended Scales:
The recommended scales for use on technical drawings
are given in Table. The scale and the size of the object in
turn, will decide the size of the drawing.

Scale Specification:

If all drawings are made to the same scale, the
scale should be indicated in or near the title block. Where
it is necessary to use more than one scale on a drawing, the
main scale only should be shown in the title block and all
the other scales, adjacent to the item reference number of
the part concerned or near the drawings.

Tips for Dimensioning:

1. As far as possible, dimensions should be placed
outside the view.
2. Dimensions should be taken from visible outlines
rather than from hidden lines.
3. Dimensioning to a centre line should be avoided
except when the centre line passes through the centre of a
4. Each feature should be dimensioned once only on a
5. Dimensions should be placed on the view or section
that relates most clearly to the corresponding
6. Each drawing should use the same unit for all
dimensions, but without showing the unit symbol.
7. No more dimensions than are necessary to define a
part should be shown on a drawing.
8. No features of a part should be defined by
more than one dimension in any one direction.
types of dimensioning chain and parallel