Definition: The sketches are drawn according to the standard accepted practices
to convey all the necessary information to a worker for manufacture a structure is
known as ENGINEERING DRAWING.
Since Engineering drawing conveys the technical information through a graphic
means, It is called graphic language .
Drawings prepared in one country may be utilized in any other country irrespective of
the language spoken. Hence, engineering drawing is called the universal language
drawing practice must follow certain rules, if it is to serve as a means of
communication. For this purpose, Bureau of Indian Standards (BIS)
adapted the International Standards on code of practice for drawing
Role of Engineering Drawing
The ability to read drawing is the most important
requirement of all technical people in any profession.
As compared to verbal or written description, this method is
brief and more clear.
The subject in general is designed to impart the following
1. Ability to read and prepare engineering drawings.
2. Ability to make free - hand sketching of objects.
3. Power to imagine, analyze and communicate, and
4. Capacity to understand other subjects
Drawing Instrument and Aids
The Instruments and other aids used in drafting work are listed below:
1. Drawing board
2. Mini drafter
3. Instrument box
4. Set squares
6. T- squares
7. French curves
8. Drawing sheets
14. Erasing shield
15. Drawing clip, pin, tape
17. Pro circle
DRAWING BOARD: Drawing Board Until recently drawing boards used are made of
well seasoned softwood of about 25 mm thick.
The wood portions are joined by tongue and grove type joint to prevent cracks.
At the edge of board, straight ebony edge is provided for the T-square usage.
Different types of drawing boards and their sizes according to IS classification are listed
. Sl. No Designation Length X Width X Thickness
To be used with sheet size
01 D0 1500×1000×25 A0
02 D1 1000×700×25 A1
03 D2 700×500×15 A2
04 D3 500×350×15 A3
Mini drafter is an instrument which can be used for multiple functions in drawing.
It contains two arms which is adjustable to required angle and at the end of the lower arm a scale set is
The scale set contains two scales connected perpendicular to each which cannot be separated.
This instrument is fixed to the drawing board at one edge with the help of screw provided for the drafter.
Mini drafter is used for drawing horizontal lines, vertical lines, inclined lines, angles, parallel lines,
perpendicular lines etc.
Set-squares are made of transparent plastic and are available in the shape of triangles,
having a French curve or simply a gap cut in the body.
These are used for drawing short straight lines, measuring and drawing certain
Used to draw vertical & inclined parallel and perpendicular lines quickly and
A good combination of set-squares is 30O x 60O set square with a long edge of 250 mm
a 45O set squares with each edge of 200 mm
Protractor is used to draw and measure the angles of lines in the drawing. It is transparent and made of
plastic. It is in the shape of semi-circle, and the edge of semi-circle part consists reading with one-degree
The bottom line joins the 0o to the 180o. The center of this bottom line is marked as “O” or “C” from which
the angles are measured.
T square is used to draw horizontal and vertical lines on drawing sheet.
It made of wood or plastic and in T shape.
The vertical part of T is called as blade and horizontal part of T is called as head.
The edge of head is uniform level and attached to the edge of the board.
The working edge is used to draw lines anywhere on the sheet by moving the
instrument top to bottom.
French curves are made of plastic and they are in irregular shapes.
Sometimes the drawing requires irregular curves or shapes or arcs which cannot be drawn using
compass. In that case French curves are suitable.
Generally French curves are more suitable for small curves and for long curves splines are used.
Drawing sheet is a white paper on which an object is drawn which is available
in various sizes.
The sheet used for engineering should be of good quality.
It should be white in color with uniform thickness with must resist the easy
torn of paper.
The surface of sheet must be smooth.
The ISO ‘A’ series of sheet sizes is based on a constant width to length ratio of
1:√2 (rounded to the nearest millimeter).
The A0 size is defined as having an area of one square meter (1 m2).
Paper weights is expressed in grams per square meter. Each smaller sheet
size is exactly half the area of the previous size.
Various sizes of drawing sheets recommended by Indian standards are listed
The two types of pencil is used in engineering drawing practice are,
1) wooden pencil 2) mechanical clutch pencil
These are the most common types of pencil, and are encased in wood. They are (LEAD) made of a
mixture of KAOLINE (CLAY) and GRAPHITE, Of varying the proportion of these get the
If increase the kaoline then hardness of pencil.
Hardest pencil is 9H grade, & Softest pencil is 7B
B: In CHISEL edge long straight
lines of uniform thickness can easily
C: The conical Point is used in
sketch work and lettering.
These are aids used for drawing small features such as
circles, arcs, triangular, square and other shapes and
symbols used in various science and engineering fields
Clinograph is an instrument used to draw parallel & Perpendicular lines lines to
the inclined lines. It contains one adjustable wing or strip which can be adjusted to
required angle. So, it can be termed as adjustable set square.
Dividers are used chiefly for transferring distances and occasionally for
dividing spaces into equal parts. i.e. for dividing curved and straight lines into
any number of equal parts, and for transferring measurements.
An eraser shield is a thin sheet of stainless steel or plastic with
slots and holes of different shapes.
They are designed to allow erasers to be used through them to
erase lines and text without removing lines close by which do
not need to be (or should not be) erased.
They are about the size of a business card but the shape of the
slots depends on the manufacturer.
Drawing clips, pin & tape
When the drawing sheet is placed on the board it may not be in fixed position.
To fix the drawing sheet to the board paper holders are used.
Generally used paper holders are thumb pins, spring clips, stick tapes etc. Care should be
taken while removing the clips or tapes otherwise the sheet may tare.
Eraser is used to remove the lines or spots which drawn by mistake or with wrong
The eraser used should be of good quality and soft. It should not damage the paper
Compass is used to draw an arc or circle with known dimensions
on engineering drawing.
It is generally made of steel and consists two legs.
One leg contains needle at the bottom and other leg contains a
ring in which a pencil is placed.
The needle tip is placed at the respected point and pencil tip is
adjusted to the height at least 1mm just above the tip of the
needle. The gap is nothing but the paper thickness.
It is made up of acrylic or transparent plastic,
it is used to draw circles of different radius quickly & accurately.
Circles are varying from dia2mm to dia30mm.
Each circle has four quadrant marked on its circumference, which are used to
locate the circle along the center line
Here are the instructions to use a simple roll-n-draw.
Graduated in both English and metric, it is a multi-purpose drawing tool made from high impact plastic for students, artists,
and designers.. It includes many useful formulas and conversion factors. Use it to draw horizontal and vertical parallel lines
with ease, as well as circles, curves, or arcs. It even has a built-in protractor to draw angles.