1. Dimensioning a Drawing
Types of Lines
and
Dimensioning a Drawing
Standard Grade

2. The Importance of Dimensioning Correctly
Drawings need to be accurate
They need to show correct dimensions
Dimensions need to be clear
They must to conform
to British Standards so
that all people who need
to use them understand
their meaning: people
like
Builders
Architects
Construction
Engineers etc

3. Types of Lines and Their Use
a. Outlines (thick and continuous)
b. Projection lines, cross hatching lines (thin and continuous)
c. Hidden lines and edges (thin short dashes)
d. Centre line (thin chain lines)
e. Cutting plane line (thick at ends with heavy closed arrows) e d b a c X
End Elevation X
Section XX
The 3 views shown above are drawn in 3rd angle projection: the symbol is shown opposite

4. Gap between the drawing
Dimensioning
Dimension
line
Dimension
(should not rest on
the dimension line)
Terms
Leader line a
Closed
arrowheads b e
When dimensioning a
drawing it should be
done so that the reader
sees the dimension from straight on as at A f
or from the right as at B
In each case the the
dimension is above the
dimension line. A d c B
Sizes are always
shown in millimetres
eg unless otherwise stated
Gap between the drawing
and the leader line

5. Dimensioning Circles and Arcsb d O c R
The symbol for a diameter is R
The symbol for a radius is

6. Fillets, Chamfers and Angles
(normally 45 )
Fillet
(usually drawn freehand) X X

7. Dimensioning
Round Bars O a b c d

8. Add dimensions to your drawing of a small train
There should be enough shown sizes to make the toy

9. This drawing shows where most of the dimensions should bej i c d b a f g h e
Add the other missing dimensions yourself