§ 4. Accessories and devices

When performing graphic works, various accessories and devices are used that facilitate the work of the draftsman, create convenience and increase productivity. In fig. 1 shows a drawing board with drawing accessories on it.

The drawing board serves for pinning paper buttons to it. It is a wooden shield consisting of longitudinal planks, tightened with end external planks and fastened with glue. The working surface is represented by longitudinal planks made of soft wood - alder or linden. Boards manufactured in various sizes. For example, the drawing board №2 has a length of 1000 mm, a width of 650 mm and a thickness of 20 mm.

T-square consists of a long ruler and two short slats. One of the crossbars is connected with a long ruler motionless, the second can be rotated with respect to a large ruler at any angle. In this way, parallel horizontal and inclined lines can be drawn with the help of a rail link.

Fig. one

Measuring ruler is used to measure the length in the drawing. It is made of solid wood and in the cross section has the shape of a symmetrical trapezium. The ruler is equipped with white celluloid strips pasted on its inclined sides and having a rectilinear uniform scale with a scale of 1 mm.

Squares are used to work with them separately or in combination with a rack. With their help, you can perform various geometric constructions; drawing a series of parallel lines, building mutually perpendicular lines, drawing corners and polygons, dividing the circle into a given number of equal sections.

Pieces are used to draw curves. They are thin plates of curvilinear shape, making it possible to draw curved lines that cannot be made with a compass. Patterns are made with different curvature lines. For drawing the curve curve, the piece is selected so that its edge coincides with at least four points of the curve; at the same time connect only two of them with a line and then move the piece to the next points.

A protractor is used to measure and lay corners in a drawing.

Stencils and templates are used to reduce the cost of labor and time to perform certain types of graphic works. In form, they can be very diverse depending on their purpose. With the help of stencils and templates, inscriptions can be made, circles, rectangles, corners, signs drawn.

Drawing devices are used to facilitate the work of a draftsman, to reduce the time spent on performing graphic works. Currently used various designs drawing instruments. They allow you to simultaneously replace the tire, protractor, square, ruler.

The drawing device (Fig. 2) includes two rulers installed at an angle of 90 ° to each other.

With the help of a special swivel head ruler can be positioned at different angles of inclination to the specified lines. The head is connected by a system of movable levers, allowing it to be moved across the field of the drawing, with a clamp bracket, with which it is attached to the drawing board. The use of such a device reduces the time spent by about one quarter against the implementation of drawings with the use of a rail.

For the mechanization of graphic works, more complex drawing machines and combines are also used.

Fig. 2

The hatching device serves to draw a series of parallel lines serving as hatching of individual sections of the drawing. It consists of two rulers, one of which is hinged at its end to the other with the possibility of moving the hinge along the second ruler by a predetermined value.