WHAT IS A FRENCH CURVE?
A French curve is a template made out of plastic, metal or wood composed of many different curves. It is used in manual drafting to draw smooth curves of varying radii.
The curve is placed on the drawing material, and a pencil, knife or other implement is traced around its curves to produce the desired result.
Modern computer-aided drafting (CAD) systems use vector-based graphics to achieve a precise radius, so no template is required.
This set of the three most common French curves is also known as a Burmester set. The one on the far left side is most commonly used for hyperbolas; the smaller one on the far right side is suited for ellipses. The large one below is used most for parabolas.
HOW TO USE A FRENCH CURVE
The french curve is used to draw a smooth line through predetermined points. After the points are plotted, a light pencil line should be sketched to connect the points in a smooth flowing line. To draw the finished line over the freehand line, match the various parts of the french curve to various segments of the freehand curve. Avoid abrupt changes in curvature by placing the short radius of the french curve to the toward the short radius portion of the line to be drawn. Change your position around the drawing board when necessary so that you can work on the side of the french curve that is away from you. You should avoid working on the "under" side of the french curve. Place the french curve so that it intersects at least two points of the line. When drawing the line along the edge of the french curve, stop short of the last point intersected. Then move the french curve along to intersect two or three more points and make sure that the edge of the curve connects smoothly with the line already drawn.
DIFFERENT KINDS OF FRENCH CURVE
French Curve Set 3 Green Tint - It contains three of the most popular curves, made of tough 0.080" green tinted plastic, in a vinyl storage envelope.
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Professional Topaz Color French Curve Set  Set of 3 Topaz-color French Curve: Contains three popular curves, packaged in a vinyl envelope. Made of acrylic-topaz, each one offers a double-beveled inking edge to prevent smudges and a tempered, scratch-resistant surface. 
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BACKGROUND OF THE INVENTION
This invention relates to a drawing apparatus, specifically one that allows the user to generate smooth arced and curved lines. Draftsmen and designers are frequently required to generate smooth and unique curves for their work.
In the design industry, there is often the need to produce and include curved lines within drawing projects. Currently most designers and draftsmen use a French curve. The French curve is non-adjustable template, and accordingly a designer or draftsperson often chooses a French curve that is most similar to the curve they wish to create or trace. French curve templates limit and influence and designers creativity and skill to the amount of French Curve templates he or her may have available to them. To counterbalance the limits of the French curve, designers and draftsmen are required to have a large set of French curves. A large set of French curves is not only expensive, but also has the disadvantages of storage and transportation, plus the need to search through the set for a matching curve. The present invention works parallel with the creative process of a designer to allow them to create a unique curve for their drawing application. Quality of drawing work is increased because the present invention allows for a unique curve to be created, while French curve templates often require several predetermined templates and curves to be used in combination to create a desired curve. The use of several templates together often shows a visible overlap of curved lines especially, when a desired curve is created with a dark medium such as a felt tip marker. The present invention allows for a unique curve to be saved by tightening the guide track into a locked position. This feature of saving the unique curve is useful if the curve later needs to be thickened or darkened with new medium. This feature also allows for a series of unique curves to be created equal distance to each other. To achive two or more curves that are equal distance to each other, the apparatus must simple be moved perpendicular to the flexible edge guide. To accomplish the same task of creating unique equal distance curves with templates is very difficult and not accurate. Furthermore the present invention allows for a unique curve to be measured and replicated again at a later time.
Several objects and advantages of the present invention are:
(a) To allow the user to create a unique curve rather that, choosing a similar, inaccurate, and predetermined curve from a template.
(b) To increase quality of drawing work because the present invention allows for a unique curve to be created, while French curve templates often require several predetermined templates and curves to be used in combination to create a desired curve. The use of several templates together often shows a visible overlap of curved lines especially, when a desired curve is created with a dark medium such as a felt tip marker.
(c) To allow for a unique curve to be saved by tightening guide track into a locked position.
(d) To allow for a series of unique curves to be created equal distance to each other.
(e) To allow for a unique curve to be measured and replicated again at a later time. Further objects and advantages of my invention will become apparent from a consideration of the drawings and ensuing description.
BRIEF SUMMARY OF THE INVENTION
The purpose of this invention is to allow someone to generate smooth curves and arcs. Draftsmen and designers need to be able to generate smooth curves for projects. The present invention has the ability to create a wide range of different curves and arcs. It also allows for the curve that has been created to be recreated exactly the same at a later time or by someone else with the same instrument. This can be very useful for an automobile designer who often requires a smooth arc and may need to recreate the exact same arc later on different drafts of his or her project. Arcs are tough to trace since they can not be put against a straight edge. If a designer is tracing a drawing through a layer of vellum, the curve creator can be used to create a curved edge guide to trace along with any medium such and a drafting pen. Unlike a French curve template the present invention is able to generate a multitude of unique curve types.
