French curve
In curve rulers are rulers for precise drawing curved lines. Curve rulers are used to approximate a determined point by point function curve by a continuous curve.
Types of curve rulers
Burmester templates, named after the German mathematician Ludwig Burmester, make splines of third order dar. With them, all continuous functions can be approximated. Are usual sets with three stencils made of plastic, which can be the most common drawing tasks of the mathematical and technical education to solve well, such as the drawing of polynomial, trigonometric functions, chain lines and ellipses. There are also extensive stencil sets that offer more choice and are also suitable for larger drawing formats.
In addition, spline sets of EMDE and extensive special rates for drawings in shipbuilding are well known and commonly used.
Special Rulers are provided for certain curves, eg for drawing parabolas, hyperbolas or trigonometric functions. They are useful only very limited because the functions represented in a coordinate system is based on a certain scale. Example of this is the Parable templates, which are mainly used in the mathematics classroom
Moreover, there is flexible curve templates of rubber or plastic, which can be adapted to a virtually arbitrary curve. The flexible rubber rulers consist in the interior of a cuboid lead core that is surrounded by two flat strip of spring steel side. The ruler is thereby the flexibility in the plane allows the lead core retains its shape through the slight stiffness and the spring steel strips protect the core and mediate irregularities of the bend. Wherein a plurality of flat plastic rulers profiles interlocking, which are fixed at one end against slipping. There is therefore a certain amount of force needed to bend it into the desired curve, but this remains then lift it off the sheet obtained. In this way the curve can be easily reproduced on a plurality of sheets, or curves of a three-dimensional object to be removed. Flexible Curve Rulers are available in various lengths typically between 30 cm to 100 cm.
A special case of variable curve rulers are traditional splines, which consist of flexible wooden or plastic strips that are placed and maintained with the help of weights, clamps, screws into shape.
Applications
Curve rulers are predominantly used in training. Software for technical drawing ( CAD software ) as well as programs that may represent the result of a regression analysis graphically, curve templates from professional practice have largely displaced. However, they can also be found there still use small drawings or manual corrections to a pen plotter pens and ink drawings created extensive or in tailoring at production cuts.
- Ruler or template