1) The document discusses various drawing instruments used for technical drawings including a drawing board, T-square, set squares, protractor, scales, roll-n-draw, mini-drafter, compass, lengthening bar, bow compass, french curves, and drafting templates. 2) It also covers standard drawing sheet sizes and layout including title blocks and borders. Drawing pencils of various grades are used to draw lines of different thicknesses. 3) The main types of lines used in drawings are outlined including hidden, dimension, extension, construction, cutting plane, hatching, center, and outline lines.

1. Lines, Lettering, Dimensioning &
Scales
Mr. Yash Parikh
M.Tech. (CIM)
Assistant Professor
Symbiosis Institute of Technology, Pune.
Unit 01

2. Contents
• Drawing Instruments
• Sizes of Drawing Sheets & Layouts
• Drawing Pencil
• Types of Lines

3. Drawing Instruments

4. Drawing Instruments
• To prepare a drawing, special drawing instruments are required.
• An engineer should know use, handling & proper maintenance of
drawing instruments.

5. Drawing Instruments
Drawing board & drawing table :
• Rectangular in shape made up of well-seasoned soft wood about 25 mm
thick.

6. Drawing Instruments
T-square :
• The T-square gets its name from its shape.
• It consists of a blade & a head.
• It varies in sizes from 15 to 72 inches in length, with 36 inches being
the most common.

7. Drawing Instruments
Set square :
• Two forms are generally used.
a)30-60 degree set square of 250 mm length
b)45-45 degree set square of 200 mm length

8. Drawing Instruments
Protractor :
• Semi-circular in shape and about 100 mm in diameter.
• Used to draw & measure such angles that cannot be drawn with set-
squares.

9. Drawing Instruments
Scale:
• Made of steel, wood, plastic, etc.
• They may be flat or trapezoidal in cross-section.
• Commonly used scales are 15 cm long & 2 cm wide or 30 cm long &
3 cm wide.

10. Drawing Instruments
Roll-N-draw :
• It has a straight edge having 16 cm or 30 cm scale ruler.

11. Drawing Instruments
Mini-drafter :
• All the functions of T-square, set-squares, scales, protractor & the roll-
n-draw are combined in drafting machine called mini-drafter.

12. Drawing Instruments
Large size compass :
• The compass is used for drawing circles & arcs of circles.
• It consists of two large legs hinged together at its upper end.

13. Drawing Instruments
Lengthening bar :
• The compass can be used to draw circles up to 120 mm diameter.
• Circles more than 150 mm radius can be drawn with the aid of this.

14. Drawing Instruments
Small bow compass :
• It is used for drawing small circles & arcs of less than 25 mm radius.

15. Drawing Instruments
French Curves :
 Used for drawing smooth curved lines that are not arcs or circles.
 These are used to draw irregular curves such as ellipse, parabola,
spiral, etc.

16. Drawing Instruments
Drafting Templates :
• These are timesaving devices that are used for drawing various shapes
& standard symbols.

17. Drawing Sheets & Layouts

18. Drawing Sheets
Drawing Paper:
• The standard sizes of drawing papers recommended by BIS are,

19. Drawing Sheet Layout
• A proper sheet layout is necessary for the easy reading of the drawing.
• Following consideration should be taken while layout a drawing sheet.
i. Sheet Size
ii. Boarder Line
iii. Title Block

20. Drawing Sheet Layout

21. Drawing Pencil

22. Drawing Pencil
Drawing Pencil:
• Pencil is the tool you will be holding most of the time while creating
a drawing.
• We need to draw lines of various thickness in drawing.
• Pencils are graded according to the hardness of their graphite lead.
• A pencil with soft graphite lead is designated B & with harder lead as
H.

23. Drawing Pencil
Pencil lead:
• The uniformity in thickness of lines depends largely on this.
• These can be sharpen in two different forms.
i. Chisel edge : used for drawing long thin lines of uniform thickness.
ii. Conical point : used in sketch work & for lettering.

24. Types of Lines

25. Types of Lines
• Lines are like the alphabet of a drawing language.
• As the alphabet are used to form meaningful words, various types of lines are
used to construct meaningful drawing.
• Each line in a drawing is used in a specific sense.
• A line may be straight, curves, continuous or segmented (dashes or dots &
gaps).
• It may be thin or thick.
• In finished drawing, all lines except construction lines should be drawn very
thin & faint.

26. Types of Lines
• Line width means the thickness of a line.
• Three grades of lines are used: - THIN, MEDIUM & THICK.
• The proportions between them are 1:2:4
• As a general rule, harder grade pencils are preferred for THIN lines & softer
grades for THICK lines.
• H pencil for THICK & MEDIUM lines.
• 2H for THIN lines.

27. Types of Lines

28. Types of Lines
Outlines:
• Lines which are drawn to represent visible edges & surface boundaries of
objects. They are continuous thick lines.
Dimension lines:
• Continuous thin lines, terminated at the ends by pointed arrowheads.
Extension lines:
• Continuous thin lines, extended about 3 mm beyond dimension lines.
Construction lines:
• Continuous thin light lines drawn for constructing figures.
Cutting-plane lines:
• Long thin chain line, thick at ends only.

29. Types of Lines
Hatching lines:
• Continuous thin lines drawn at 45 degrees to main outline of the
section.
• These are uniformly spaced about 1 mm or 2 mm apart.
Hidden lines:
• Medium thick lines made up of short dashes of approx. equal lengths of
about 2 mm spaced at equal distance of 1 mm.
Centre lines:
• Drawn to show centres of object.
• Thin long chain lines composed of alternately long & short dashes
spaced approx. 1 mm apart.
• Here the longer dashes are about 6 to 8 times the short dashes.

30. Application of Types of Lines

31. Application of Types of Lines

32. Application of Types of Lines

33. Application of Types of Lines

34. Thank You