SME
Engineering Graphics & CAD · Problem type
Drawing scale
Use this for “A part is drawn at 1:5. A 300 mm edge is how long on the sheet?”
This is an example. Type your own values to start a new problem.
d (mm)
=
L (mm)
×
a
b
Formulas
d
=
L
×
a
b
60
=
300
×
1
5
Assumptions
•
A scale a:b draws a units for every b units of the part; 1:5 shrinks it, 2:1 enlarges it.
•
Every length on the sheet uses the same scale; angles are drawn true.
•
Dimensions written on the drawing still give the true size, whatever the scale.
Step-by-step
WE KNOW
a = 1, b = 5, L = 300 mm
FIND
drawn length (d)
Step 1 · Find drawn length (d)
Use d = L × a ÷ b
The
scale
says
every
b
units
of
the
part
are
drawn
as
a
units.
d
=
300
×
1
5
d
=
60
mm
Check
Put the numbers back in. Both sides should match.
60
=
300
×
1
5
✓
Topic check
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