This document provides an introduction to technical drawing. It defines technical drawing as conveying technical information using mathematical drawing instruments, often called mechanical drawings. It describes the traditional and CAD methods used to produce technical drawings. It then explains the common traditional drawing instruments like T-squares, set squares, compasses, pencils in various grades, templates, curves, erasers, and brushes. It provides examples of how these tools are used and concludes with applications of technical drawings like building, schematic, and mechanical drawings.

1. Introduction to
TECHNICAL DRAWING

2. Definition of Technical Drawing
• Technical Drawing is used to convey
information of a technical nature.
• Technical Drawing is prepared with the use of
mathematical drawing instruments. For this
reason they are often called mechanical
drawing.

3. Method used to produce Technical
Drawings
• Traditional Method
Sketching
 Computer-
Aided drafting
(CAD)

4. Traditional Methods Drawing Instrument
• Tee- Square ( T-square)
• Set- Squares
• Compass
• Pencils
• Dust free Eraser
• Radius & Circle Template
• flex or French curve
• Erasing shield

5. Tee-Square
•A T-square is used by draftsmen
primarily as a guide for drawing
horizontal lines.
• It also guide a set square to draw
vertical or diagonal lines

6. Set - Squares
• Set squares are used in conjunction with T-squares to
draw horizontal lines and accurate angles.
• There are two main types of set square:
45 degree 30/60 degree

7. Compass
• A compass is an instrument used to draw circles
or the parts of circles
Spring Bow Compass
Beam or Compass
Drop Compass
Proportional Compass

8. Compass point

9. Dust- free Eraser

10. Pencils
• A pencil is graded according to the hardness
of its lead from 7H(very hard to 7B very soft)
Draughting Note Art Work
4H 3H 2H H HB B 2B 3B 4B

11. Pencil points
• All pencil lines should be thin and clear. To obtain
these the pencil must be kept sharp.

12. Radius & circle Template
to save time, many draftsmen now use
templates for drawing small circles and
arcs.

13. Flex Curve& French Curve
• It is used in manual drafting to draw smooth
curves of varying radii.
French Curve
Flex Curve

14. Erasing shield
• These thin pieces of metal have a variety of
openings to permit the erasure of fine detail
line or note work disturbing nearby work that
is to be left on the drawing.

15. Brushes
• A light brush is used to keeping the drawing area
clean. By using a brush to remove eraser particles
and any accumulated dirt, the draftsmen avoids
smudging the drawing

16. Application of technical drawings
• Building drawing
Schematic drawing
Mechanical drawing