Reference Book
the dimension lines. They show where a dimension begins and ends.
POINTS TO BE CONSIDERED IN DIMENSIONING- Each drawing shall use the same unit for all dimensions.
- Long extension line should be avoided.
- Do not cross a dimension line with another line.
- Each feature of the object shall be dimensioned only once on a drawing.
- All dimensions which are necessary to define an object or component
must be clearly marked on the drawing. - Dimension lines are placed outside the drawings except in special cases
where marking inside the drawing is readable. - In general, dimensions should be placed outside the view outline.
- Do not use a centre line or a line of the drawing as the centre line.
FREEHAND SKETCHING
Freehand sketch is a drawing made without the help of drawing instruments.
The important uses of freehand sketching are: - It is used to convey the thoughts and ideas to the workers.
- It is used to present the ideas of the designer to the management.
- It is used for showing different layouts of the drawing.
- It is used in the production of temporary fixtures.
- It is also used to convey information regarding repair or modification
needed in an existing structure or machine.
COMPARISON BETWEEN FREE HAND SKETCHING AND INSTRUMENTAL
DRAWING
Free hand sketching Instrumental drawing
Drawing made without the use of Drawing made with the use of
drawing instrument drawing instrument
It is not drawn to actual scale It is drawn to actual scale
It is not a perfect drawing It is a perfect drawing with uniform
line thickness
It is used for temporary figures/ It gives exact details of object to be
fixtures manufactured