Sketcher Workbench/cn

The Sketcher Workbench is used to create 2D geometries intended for use in the Part Design Workbench and other workbenches. Generally a 2D geometry is considered the starting-point for most CAD models - a simple 2D sketch can be 'extruded' into a 3D shape, further 2D sketches can be used to create pockets in the surface of this shape and sketches can be used to define 'pads' (extrusions) on the surface of 3D objects. Along with boolean operations, the sketcher forms the core of generative solid shape design.

The sketcher workbench itself features constraints - allowing 2D shapes to be constrained to precise geometrical definitions. And a constraint solver which calculates the constrained-extent of 2D geometry and allows interactive exploration of sketch degrees-of-freedom.



Basics of constraint sketching
To explain how the Sketcher works, it may be useful to compare it to the "traditional" way of drafting.

Traditional Drafting
The traditional way of CAD drafting inherits from the old drawing board. Orthogonal (2D) views are drawn manually and intended for producing technical drawings (also known as blueprints). Objects are drawn precisely to the intended size or dimension. If you want to draw an horizontal line 100mm in length starting at (0,0), you activate the line tool, either click on the screen or input the (0,0) coordinates for the first point, then make a second click or input the second point coordinates at (100,0). Or you will draw your line without regard to its position, and move it afterward. When you've finished drawing your geometries, you add dimensions to them.

Constraint Sketching
The Sketcher moves away from this logic. Objects do not need to be drawn exactly as you intend to, because they will be defined later on by constraints. Objects can be drawn loosely, and as long as they are unconstrained, can be modified. They are in effect "fl