SOLIDWORKS: SKETCH RELATIONS

Transcription

1 Sketch Feature: The shape or topology of the initial sketch or model is important, but exact geometry and dimensions of the initial sketched shapes are NOT. It recommended to work in the following order: 1) Select the plane or flat surface on which to sketch. 2) Sketch characteristic shape or profile of part or feature to be created. 3) Fully define or completely constrain the geometries BY ADDING RELATIONS. 4) Add dimensional constraints (locations and sizes).

2 Sketch Status: SW indicates constrained status of entities ( lines, arcs, circles, etc.) in a sketch using a color code. The code is: Blue: Under defined (needs geometrical or dimensional constraints). Black: fully defined Red: Over defined (e.g., redundant relations or dimensions) Yellow: Invalid (e.g., self-intersecting curve) Brown: dangling (not part of a closed loop)

3 Do not extrude until your sketch is black: -If your sketch turns red: - Do not proceed. - There are unwanted relations or double dimensions in the sketch. - Correct the over-definition right then. -If sketch entity turns yellow: - Do not proceed. - There are ambiguous or impossible relations. For example two parallel lines are required to also be perpendicular or collinear or something like that. - Resolve the problem before proceeding.

4 Sketch relations are used to force a behavior on a sketch element thereby capturing design intent. - Some sketch are added automatically as geometry is sketched. - Tools also exist to create those relations that cannot be created automatically. These relations are based on selected geometry and add dimensions. - Display Relations shows and optionally allows you to remove (delete) geometric relationships between sketch element.

5 Add relations is used to create geometric relationship such as parallel, collinear, concentric or coradial between sketch elements. -Where to find it Select the sketch entity or entities and select the appropriate relation from Add Relations section of the Property Manager. Or, Click Tools, Relations, add.. Or, on the sketch toolbar click Add Relation

6 There are several common constraints utilized in fixing features. Relation Sketch Entities Changes Undergone Coincident A point and a line or arc/circle Point lies on the arc or line Collinear Two or more lines Lines line on the same theoretical infinite line Concentric Two or more arcs/circles Arcs/circles share the same center-point Co-radial Two or more arcs/circles Items share the same center-point and have equal radii.

7 There are several common constraints utilized in fixing features. Relation Sketch Entities Changes Undergone Equal Horizontal Vertical Two or more lines or two or more arcs/circles One or more lines or two or more points. One or more lines or two or more points Line lengths and arc/circle radii stay equal Lines become horizontal; points are aligned horizontally Lines become vertical; points are aligned vertically Parallel Two or more lines Lines become parallel

8 There are several common constraints utilized in fixing features. Relation Sketch Entities Changes Undergone Perpendicular Two lines Lines become perpendicular Tangent Symmetric An arc/circle or spline and a line, arc, or spline A centerline and two points. Lines, arcs or splines Items remain tangent. Items remain symmetrical about the centerline

9 There are several common constraints utilized in fixing features. Relation Sketch Entities Changes Undergone Midpoint A point and a line Point remains at the midpoint of the line. Intersection Pierce Two lines and one point A sketch point and an axis, edge, line, arc or spline Point remains at the intersection of the lines. This can be a projected intersection Sketch point becomes coincident to where the axis et. al. pierces the plane of the sketch.

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