To spend simply a circle on a plane costs nothing with the help of a compass. But what if this line should cover a cylindrical billet? For a rough layout, you can use string or a rubber ring. The marking will be more accurate if the workpiece perpendicular to lower the fluid: boundary wetting will become the desired line. Another option is to wear to the cylinder tube of suitable diameter or wrap it with a strip of paper, foil.
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ELLIPSOGRAPH
ELLIPSOGRAPH — is the name of this simple device. It can be used to draw an ellipse with any ratio of the semiaxes. It is enough to set into the holes on the line of alignment pins to...
