This document discusses drafting scales and how to use them. It explains that drawings are rarely done at true size and scales are commonly written as ratios like 1:1, 1:2, 2:1. It also describes the different types of drafting scales - decimal, mechanical engineer, metric, and architectural. The key steps for using a scale are identified as determining the scale type and factor, measuring the last full line passed, and calculating fractional measurements. Architectural and engineer scales are compared, with architectural scales using feet and engineer scales using inches. Finally, the document outlines assignments for practicing using different scales.

1. Modern Graphics Communication
Chapter #3: Using Drafting Scales
IT 161.02 – Baxter – Spring ’05

2. Scaling your drawings SIZE
(not the tools)
 Rarely do you need to draw something at it’s
actual, full, or true size
 The most common way to record scale is
 1:1 1:2 2:1 etc…..
 If the number in FRONT is larger = then the
scale is BIGGER
 If the number in BACK is larger = then the
scale is SMALLER

3. Scaling (cont)
 If the number in FRONT is larger = then the scale
is BIGGER
 So that means that 2:1 is DOUBLE the true
size
 So 4” would become 8”
 If the number in BACK is larger = then the scale is
SMALLER
 So that means that 1:2 is HALF the true size
 So 4” would become 2”

4. Scaling (cont)
 Sometimes you will have to create your own scale
ratio
 For example when drawing maps. They do make
Civil Scale tools.
 However, usually you decide & note the scale
ratio:
1” = 100’ so 2” would actually be 200’
1” = 30’ so 5” is actually 150’
Etc…

5. Types of Drafting Scales
 There are actually five different types
 These are:
– Decimal
– Mechanical Engineer
– Metric (we will use)
– Engineers (we will use)
– Architectural (we will use)

6. How to read a Scale:
 What type of drafting scale are you using?
 a. Mechanical/Engineer, Architectural, etc.
 b. Mechanical /Engineer Scales are used
when scaling the size of the standard inch.
 c. Architectural Scales are used when scaling
the size of the standard foot.
Step 1

7. Step 2
 What Scale factor is being used?
 a.The Scale factor determines how
much larger or smaller a measurement
will become.
 b. Be certain to use the proper scale or
your measurements will be incorrect.

8. Step 3
 What is the last full whole number/ line passed?
 a.Position the scale so the 0 mark is even with one
end of the line.
 b. Count the number of scale inches the line has
passed.
 c. Write this
number down

9. Step 4
 Does the line stop between two inch marks?
a.If the line stops
between two inch
marks then a
Fractional
measurement is
needed
b. Slide the scale so the other end of the line now
coincides with the largest inch mark.

10. Step 5
 How many divisions or gaps are there
between each full inch?
a. Count the total
number of subdivisions
at the fraction end of
the scale being used.
b. Write this number on
your answer blank and
place a line over the top.

11. Step 6
 What is the fractional measurement?
a. Count the total
number of fractional
marks the line passes.
b. Write this number
above the number
from Step 5.
c. If the number on top is
even then you must
reduce.
d. Divide both numbers
by 2 until the top number
is odd.

12. Architectural Engineer Scales
 Only main difference is that
Architectural (16) is based on
Feet
Engineer (10) is based on Inches

13. Architectural
Scale
(Feet)
 Actual Full Size:
 16
Reduction:
¼ ( ¼ = 1’-0”)
½ ( ½ = 1’-0”)
Etc..
Enlargement:
1 ½ ( 1 ½ = 1’-0”)
3 ( 3 = 1’-0”)

14. Architectural Scale(Feet)
All line indicators before the zero represent inches. All
line indicators after zero represent feet.

16. Engineer
Scale
(Inches)
 Actual Full Size:
 10
Reduction:
20 (Half or 1/2)
30 is (Third or 1/3)
40 (Fourth or 1/4)
60 (Sixth or 1/6)
Etc..
Enlargement:
On the scale tool = none
Usually defined by you,
1”=50’, etc…

17. Engineer Scale
10 Regular
Inches= 1” OR Feet = 1’-0”
10: 10
Inches= 10” OR Feet = 10’-0”

18. The Metric System Basics
 The metric system originated in France in the 1790s, as an alternative
to the traditional English units of measurement. The new system was
to standardize the units of measurement as trade expanded
throughout continental Europe. Although metrics have been used
internationally in scientific fields for many years, the push to convert
the world to exclusively using the metric system only began in the
1970s.
 Today many countries have adopted an exclusively metric system of
measurement. The United States, however, remains one of the last
countries in the world to go fully metric.
 As a result much confusion still exists. Now, more than ever, people
need information on metrics in a form that relates directly to them in
their personal and professional lives.
 This website Metrication.com has been designed to meet these
demands.

19. Metric Scale
 Actual Full Size:
 1:10
Enlargement:
On the scale tool = none
2:1
5:1
10:1
Reduction:
1:2 (Half)
1:25 (Fourth)
1:5 (One Fifth)
Etc…

23. Summary
 Being able to read a ruler, identify or
determine the correct scale, & then to know
which scale tool to use is crucial.
 You must be able to work with each and
apply them to the correct situation or need.
 Just like when you learned to read an inch,
practicing measuring with the different
scales will lead to mastery.

24. Assignments
 Remember to use correct lettering
techniques.
 Complete the worksheets given
 Scale Test combining all three (3) basic
types