In the modeling practice is often necessary for the creation of ellipses of various sizes, with different ratios of semi-axes. There are several ways of constructing such figures. But they are not without drawbacks. Well, I offer reliability and simplicity. However, the required pantograph is a device well-known to widely used. Moreover s requires no change in its design.

The construction of the ellipse is as follows. The pantograph is installed on the decrease, that is, so that his pole was located in the corner. To improve the accuracy of building is necessary to make a metal copy be machined in the plastic ring groove. Boarded the diameter of this ring is to be equal to 1/10 of the length of the arm of the pantograph, for the construction of an ellipse does not require any calculations. Let’s say you have an arm with shoulder length 500 mm.

Therefore, the diameter of the guide ring is equal to 50 mm. In this case, you would construct an ellipse with the minor axis of 5 mm and large — up to 45 mm. to obtain a figure larger or smaller, you will need either a copier with a groove of a different diameter or arm with the other shoulder.

To obtain the ellipse with the given axes, it is necessary to postpone the sizes of these axes multiplied by ten, perpendicular to the shoulders of the pantograph Difficult? Not at all. Let’s try. For example, you need the ellipse with the axes 27 and 37 mm. On two parallel scales of pantograph you save 27 cm, and the third, perpendicular to them, — 37 see the result in the trace copier circles Ø 50 mm will be mathematically correct ellipse with the specified parameters.

When marking on paper as a writing device, you can use a pencil or ballpoint pen to draw on metal or plastic — steel needle of the Scriber.

**N. BOGOSLOVSKY, G. Epist**

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