Content:
Home page
1. Drawing board.
2. Inertial Drawing Tire.
3. Stencils for dashed lines.
4. Device to build tangents and normals to curved lines.
5. How to divide a line and a circle into equal and unequal parts.
Fixture for building tangent and normals to curved lines.
Conducting tangents and normals to curved lines (even to a circle) is a rather complicated graphic task requiring certain geometric knowledge. Most often, solving such problems cannot be done without special literature.
But is it possible to formalize the solution of the problem and use the simplest drawing device for these purposes? It turns out you can, and it’s not even very difficult to make it, and to use it is quite simple.
The device is shown in Fig. 6 a. The diagram also shows the construction of a normal at a point A and a line tangent to the curve.
Click to enlarge.
The device has the form of a T-shaped ruler. In one of the rulers (the crossbar of the letter T), an angular groove is made, at the ends of the base of which two installation needles are mounted. From the top of the corner groove opposite the base (the outer edge of the ruler), a pointer “emerges” - a thin and rigid plate, oriented edge to the plane of the ruler. Note that the ruler (the crossbar of the letter T) is used to draw tangents.
In the second ruler (leg of the letter T) there is a longitudinal slot for the normal. The axis of the slot coincides, of course, with the axis of the aforementioned pointer.
Work with the device as follows. Let there be a certain curved line [Fig. 6.6). It is necessary to restore the normal to this curve of the line at point A. In this case, place the fixture on the drawing so that the installed needles are on the line itself, and the pointer would pass through this point A. With this installation, the slot in the ruler will be oriented “normally” to the curve of the line at point A. It remains to insert a pencil into the slot and draw a line, which then will have to be completed to point A after removing the device. (The tangents are drawn in a different line.)
Content:
Home page
1. Drawing board.
2. Inertial Drawing Tire.
3. Stencils for dashed lines.
4. Fixture for constructing tangents and normals to curved lines.
5. How to divide a line and a circle into equal and unequal parts.