1. Double circle painting.
2. Draw in three circles. .
3. Quick approximate drawing. ♂ Accurate drawing of the curvature of oval head;
1. concentric circle method. (Please refer to the book "Riveting Technology" for the above painting method. )
2. Formula method. -First calculate the focus using the mathematical ellipse formula. When unfolding, nail a nail at the focus, wrap a thin steel wire around two nails to form a triangle with the end of the short axis, and you can draw a standard ellipse.
3.CAD drawing method. -Draw a standard ellipse of 1: 1 with CAD drawing software, and print it according to the standard of 1: 1. Firstly, make a straight line on CAD, the length of which is the outer diameter d of the elliptical head, and make the center line I of this straight line.
In addition to the total height of the head, look up the table, then make a straight line parallel to the outer diameter of D (intersecting with the center line at point A), then look up the height of the straight side of the table, draw an ellipse with the ends of the straight side height as the endpoints of the long axis of the ellipse and point A as the endpoints of the short axis, and then delete the redundant lines.