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Method of construction ellipse
1- Circle Method
A. Draw a circle with a diameter equal to the major axis and a circle with a diameter equal
to the minor axis using the same center.
B. Divide the circles into 12 slices using your 30 deg set square.
C. Draw a vertical line down from each point where the lines meet the outer circle and
draw a horizontal line across where the lines meet the smaller circle. Mark out the points
where the horizontal and vertical lines meet.
D. Use these points and curve template to draw the ellipse
Watch:
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Another way for drawing:
2- Draw an Ellipse by Four-Center Method
A. Draw the major axis, AB, and the minor axis, CD, which are
mutually perpendicular at the midpoint, O, as shown in the
diagram.
B. Draw AD, that connects the end points of the two axes.
C. Using a compass, point the tips of it to DO then plot it along
AO and reset the compass on the remaining distance to O.
D. With the difference of semi axes thus set on the dividers, mark
off DE equal to AO minus DO.
E. Draw perpendicular bisector AE, and extend it to intersect the
major axis at K and the minor axis at H.
F. With the compass, mark off OM equal to OK, and OL equal
to OH.
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G. With H as a center and radius R1 equal to HD, draw the
bottom arc.
H. With L as a center and the same radius as R1, draw the top
arc.
I. With M as a center and the radius R2 equal to MB draw the
end arc.
J. With K as a center and the same radius as R2, draw the other
end arc.
K. The four circular arcs thus drawn meet, in common points of
tangency, P, at the ends of their radii in their lines of centers.
Watch:
3- Drawing ellipse by rectangular method
A. Draw your Major and Minor Axes.
B. Now draw a rectangle around the Major and Minor Axes as shown.
C. Divide both halves of the Major Axis into an equal number of parts. Here we have used
four parts. Now divide each half of the edges of the light blue rectangle, corresponding
to the Minor Axis, into the same number of parts. Label all of these points as you see
in the diagram.
D. Next you have to join the ends of the Minor Axis to the divisions on the edge on the
rectangle. Then from the opposite end of the Minor Axis draw lines through the
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divisions on the Major Axis until they intersect the first set of lines you have drawn.
Here we have only shown half of the lines for clarity.
E. Here you can see the completed set up.
F. Join up all of the points of intersection and the points labeled '0' to form your Ellipse.
G. And now you are finished. You can draw an Ellipse in any direction with this method,
but remember you must know the length of the Major Axis and the Minor Axis, or be
able to find them out.
Watch:
https://www.youtube.com/watch?v=dXsBzzTyIxo
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4- Accurate Ellipses
To make the framework, we need to first create a rectangle with the proportions of the major
and minor axes of the ellipse. we then need to divide this rectangle into 16 equal sections.
At this point we now know 4 of our points and we have divided our rectangle into 4 equal
sections. We now need to divide each of those sections into four more sections.
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We now have 16 equal sections. However, before going further let's remove the diagonals used
in constructing those sections to keep things from getting too visually confusing.
Mohanad N Noaman Electronic Engineering College Ni nevah University
Mohanad N Noaman Electronic Engineering College Ni nevah University