Chapter 1 Dimensions and Relations

Smart Dimensions Click once on a line, and a linear dimension is created: – Depending on where you drag the dimension, it can be along the line, horizontal, or vertical: INTRODUCTION TO SOLID MODELING USING SOLIDWORKS 2009

Smart Dimensions (cont.) Click once on a circle, and a diameter dimension is created: Click once on an arc, and a radial dimension is created: INTRODUCTION TO SOLID MODELING USING SOLIDWORKS 2009

Smart Dimensions (cont.) Click on each of two parallel lines to create a linear dimension for the distance between the lines: INTRODUCTION TO SOLID MODELING USING SOLIDWORKS 2009

Smart Dimensions (cont.) Click on each of two non-parallel lines to create an angular dimension: INTRODUCTION TO SOLID MODELING USING SOLIDWORKS 2009

Smart Dimensions (cont.) Click on two points to create a linear dimension: INTRODUCTION TO SOLID MODELING USING SOLIDWORKS 2009

Smart Dimensions (cont.) When a dimension is created between a circle or arc and another entity, the dimension is to the center of the circle or arc: INTRODUCTION TO SOLID MODELING USING SOLIDWORKS 2009

Relations Relations can apply to a single entity: Or to multiple entities: Vertical: Horizontal: Fixed: Perpendicular:Parallel: Equal: INTRODUCTION TO SOLID MODELING USING SOLIDWORKS 2009

Relations (cont.) Relations can be viewed, added, or deleted from the PropertyManager by selecting any sketch entity: INTRODUCTION TO SOLID MODELING USING SOLIDWORKS 2009

Relations (cont.) Select multiple entities by holding the Ctrl key while making selections. Relations between the entities can be viewed,added, or deleted from the PropertyManager: INTRODUCTION TO SOLID MODELING USING SOLIDWORKS 2009

Viewing Relations Select View: Sketch Relations from the main menu INTRODUCTION TO SOLID MODELING USING SOLIDWORKS 2009

Automatically Created Relations Snaps create relations automatically When drawing sketch entities, pay close attention to the relation icons by the cursor: Examples: New line will begin at a point on the existing line New line will begin at a specific point (in this case, the midpoint of an existing line) INTRODUCTION TO SOLID MODELING USING SOLIDWORKS 2009

Automatically Created Relations (cont.) More examples: New line will be perpendicular to an existing line New line will be collinear with an existing line New line will end on an existing circle and be tangent to the circle INTRODUCTION TO SOLID MODELING USING SOLIDWORKS 2009

Relation Icons INTRODUCTION TO SOLID MODELING USING SOLIDWORKS 2009 Tangent Symmetric Pierce Along x (3D Sketch) Horizontal Vertical Parallel Perpendicular Coincident Midpoint Intersection Equal Concentric Coradial Fixed Collinear

Fully Defined Sketches A sketch is fully defined if: – The size and shape of every sketch entity is defined and – The position of the sketch in 3-D space is defined Fully defined sketches are not required, but represent good design practice INTRODUCTION TO SOLID MODELING USING SOLIDWORKS 2009

Example Consider this T-section: INTRODUCTION TO SOLID MODELING USING SOLIDWORKS 2009

Example (cont.) These dimensions are sufficient to define the part if we assume that the section is symmetric: INTRODUCTION TO SOLID MODELING USING SOLIDWORKS 2009

Example (cont.) However, these dimensions are necessary to apply the symmetry condition: INTRODUCTION TO SOLID MODELING USING SOLIDWORKS 2009

Example (cont.) However, the sketch is still under defined until its position is 3-D space is defined The sketch plane, along with the location of the sketch relative to the origin or an existing point on the part defines position Midpoint of line coincident with origin INTRODUCTION TO SOLID MODELING USING SOLIDWORKS 2009

Example (cont.) The sketch is not fully defined unless the lines are horizontal and vertical – show Sketch Relations: Horizontal Vertical INTRODUCTION TO SOLID MODELING USING SOLIDWORKS 2009

Example (cont.) Two dimensions can be replaced with relations: EQUAL INTRODUCTION TO SOLID MODELING USING SOLIDWORKS 2009

Example (cont.) Advantages of using relations: A minimum number of dimensions is required, and symmetry is maintained when dimensions change INTRODUCTION TO SOLID MODELING USING SOLIDWORKS 2009