Theory of CAD I

Sketches, 2D

ENSC 489

Mike Henrey

September 16, 2015

Geometry and terminology

Axis

Plane

Origin

Geometry and terminology

Face

Edge

Vertex

Base feature first feature created

Degrees of freedom (DOF)

DOF

Point on a 2D sketch

DOF

Line on a 2D sketch

DOF

Arc on a 2D sketch

Relations

In SolidWorks, you can add relations between sketch elements

Relations work by reducing the number of DOF that each sketch element has

Note that dimensioning a sketch element also reduces the number of DOF that the element has in this sense, a dimension is a type of relation

Coincident

Points

Line and point

Arc and point

Horizontal/Vertical

Points

Co-radial

Arcs and circles

Equal

Radius

Lines

Other

Parallel

Perpendicular

Tangent

Fully constrained

In SolidWorks, when a sketch is fully constrained, all the sketch elements become black

From Sketch to 3D

Basic workflow in SolidWorks:

Select a (2D) plane

Sketch on the plane

Create 3D geometry from the sketch

Select new plane, repeat