This document discusses mechanical drafting and scaling. It explains that scaling allows drawings to be made proportionally larger or smaller than the actual object using scale ratios. Common scale ratios discussed are 1:1 for full size, reduced scales from 1:10 to 1:500 to fit large objects on paper, and enlarged scales from 2:1 to 500:1 to show details of small objects. Guidelines are provided for dimensioning and maintaining angles when scaling drawings.

1. MECHANICAL DRAFTING
ARCHIBALD S. SALANGSANG
SECONDARY SCHOOL TEACHER I

2. MECHANICAL DRAFTING
SCALING
• PROPORTION – a size or distance in comparison
to another.
• PROPORTION SCALE – a scale for measuring
distances for drawings. Marks on a proportion
scale indicate the reduced size in proportion to the
full or actual scale.
• SCALE – a graduated measurement to allow
production of a drawing to any size desired.

3. MECHANICAL DRAFTING
THE SCALE
• The measuring tool,
called the SCALE
(commonly known as the
metric scale), has several
edges.
• Each edge is called the
PROPORTION SCALE.

4. MECHANICAL DRAFTING
THE SCALE
• It helps the drafter to
REDUCE or ENLARGE
the drawing of an object
in proportion to its actual
size.

5. MECHANICAL DRAFTING
FUNCTION OF A SCALE
1. To measure or layout line distances accurately
either in full size and larger or smaller than full size.
2. To produce drawing to a certain sizes (making drawing
into scale)

6. MECHANICAL DRAFTING
THE SCALE RATIO
(OBJECT/DRAWING)
PROPORTION SCALES
Most drafting scales are equipped with proportion scales.
Each of these scales aids the drafter in reducing an object
on a drawing in a different proportion.

7. MECHANICAL DRAFTING
THE SCALE RATIO
(OBJECT/DRAWING)
FULL-SIZE SCALE – has a ratio of 1:1
• This means that 1 mm on the drawing represents 1 mm
of the actual object.
• The views on the drawing paper are the same size as
those of the actual object.

8. MECHANICAL DRAFTING
THE SCALE RATIO
(OBJECT/DRAWING)
SCALE RATIO 1 : 1 – means that 1 mm. on the drawing
represent 1 mm. on the actual product or work piece.

9. MECHANICAL DRAFTING
THE SCALE RATIO
(OBJECT/DRAWING)
REDUCED SCALE (SCALED-DOWN) – has a ratio of 1:2.
This means that 1 mm on the drawing represent 2 mm on
the actual object.
The views of the actual object are twice the size of the
views on the drawing paper.

10. MECHANICAL DRAFTING
THE SCALE RATIO
(OBJECT/DRAWING)
REDUCED SCALE (SCALED-DOWN)
This scale is usually used to draft huge/large actual objects
so that they can fit into the drawing paper. Common
reduction scales used are :
1: 25 1:50 1:100 1:200 1:250
1: 10 1:20 1:40 1:300 1:500

11. MECHANICAL DRAFTING
THE SCALE RATIO
(OBJECT/DRAWING)
ENLARGED SCALE (SCALED-UP) – has a ration of 2:1
This means that every 2 mm on the drawing represent 1
mm on the actual object.
The views on the drawing paper are twice the size of
those of the actual object.

12. MECHANICAL DRAFTING
THE SCALE RATIO
(OBJECT/DRAWING)
ENLARGED SCALE (SCALED-UP)
This scale is primarily used in drafting small/tiny objects so
that its details can be more presented in the drawing
paper. Common enlargement scales used are
2: 1 5:1 10:1 50:1
100:1 200:1 250:1 500:1

13. MECHANICAL DRAFTING
THINGS TO REMEMBER
IN SCALING A DRAWING
1. Whenever possible, the work piece must be drawn into
full-size.

14. MECHANICAL DRAFTING
THINGS TO REMEMBER
IN SCALING A DRAWING
2. When dimensioning,
always enter the
actual dimension of
the work piece.

15. MECHANICAL DRAFTING
THINGS TO REMEMBER
IN SCALING A DRAWING
3. Angular dimensions remain the same regardless of the
scale to which an object is drawn.

16. MECHANICAL DRAFTING
THINGS TO REMEMBER
IN SCALING A DRAWING
4. The first figure of a scale designation refers to the
dimension used to construct the views.
The second figure of a scale designation refers to the
actual dimensions of the object being drawn.