Unidad Didáctica para 1ºESO: Dibujo Técnico

1. TECHNICAL
DRAWING
TECHNICAL DRAWING & BASIC
GEOMETRIC CONSTRUCTIONS
JULIA MENA GARCÍA

2. CIRCLES
CIRCLES

3. OPEN PAGE 88 ON YOUR BOOK
-LOOK T HESE WAT ER LILY PLANTS, AND T HOSE ORANGES CUT IN HALF.
-NAME AS MANY CIRCULAR T HINGS YOU CAN T HINK OF THAT ARE FOUND IN
REAL LIFE.

4. LET’S SEE THE DIFFERENCES BETWEEN...
A CIRCLE AND AN ELLIPSE
A circle has only one axis, while an ellipse has two.

5. LET’S SEE THE DIFFERENCES BETWEEN...
A CIRCLE AND AN SPHERE
CIRCUMFERENCE CIRCLE SPHERE
A circle is two dimensional while a sphere is three
dimensional

6. USING THE COMPASS
A compass is used to make curved shapes or
circles. It is also used to create line segments of
equal lenght.
It is an easy to use and precise drawing tool. In
technical drawing, compasses are used for
inscribing perfect circles or arcs.
The compass can be named as well as a pair of
compasses.

7. THE CIRCUMFERENCE
A circumference is the length of the closed curved line of the
circle.
A circle has a centre point and every point on the closed curved
line is the same distance from the centre point.
EXERCISE
Now do the exercise 9 on page 87. Draw a circumference
knowing three points and no centre.

8. OPEN PAGE 87 ON YOUR BOOK
LET’S DO THE EXERCISE

9. Join points A and B and draw the line segment bisector.

10. 90º
Then do the same thing with points B and C.

11. Note that the point where both perpendicular bisectors
cross is the centre of the circumference.

12. RADIUS
-Finally, draw a circumference using that point as
the centre and any of the other points.

13. RADIUS
-Finally, draw a circumference using that point as
the centre and any of the other points.

14. -Concentric circumferences have the same axis.
-A tangent interior circumference touches the interior circumference of another
circle.
-An external circunference doesn’t touch the other circumference.
-An intersecting circumference intersects another circumference in at least two
points.
EXTERNAL CIRCUMFERENCE INTERNAL CIRCUMFERENCE
TANGENT EXTERIOR
CIRCUMFERENCE
TANGENT INTERIOR
CIRCUMFERENCE
INTERSECTING CIRCUMFERENCE
CONCENTRIC CIRCUMFERENCES

15. OPEN PAGE 87 ON YOUR BOOK
LET’S DO THE EXERCISE

16. OPEN PAGE 87 ON YOUR BOOK
EXAMPLE

17. OPEN PAGE 81 ON YOUR BOOK
WE WILL LOOK AT HOW TO CARRY OUT SOME COMMON GEOMET RIC
CONST RUCT IONS USING A COMPASS AND A RULER.
CREAT E A FREE COMPOSIT ION MADE UP OF CIRCLES USING A COMPASS AND
T HEN COLOUT T HEM WIT H PENCILS OR FELT-T IP PENS.
IF YOU HAVE COMPASS ADAPTOR & EXTENSION, YOU CAN USE T HEM TO VARY
T HE SIZE AND DRAW T HE SHAPES WIT H T HE COLOURS.

18. EXAMPLE