Sketch relations SolidWorks – Part IV – Summary Written by: johnsinit • Edited by: Lamar Stonecypher Published Jan 30, 2009 After you have – hopefully – studied and mastered the sketch relations of Solid Works, this article concludes the feature overview, summarizing all the relations available in SW2008. IntroductionIn addition to dimensions, defining sketch entities relations is very important. It can later save you time in dimensioning (for instance if you have equal line you would only need to define a length once) and also help you to “completely define” your sketch – preventing unexpected problems when changing dimensions and rebuilding the part.Relations overviewThe relations are of several types: Single line relations Line to point Point to Arc Line to line Line to arc or circle (here and further, circles are considered as arcs.) Arc to arc Other useful relationsSingle Line relationsHorizontal – line is parallel to construction plane X axis Vertical – line is parallel to construction plane Y axisPoint-to-Line relationsCoincident – the point lies on the line or its continuation Mid-point – the point lies exactly in the middle of the linePoint-to-Arc relationsCoincident – the point lies on the arc/circle Concentric – the point lies in the center of the arc/circle Mid-point – the point lies on the line that passes through line center and middle point.Line-to-Line relationsEqual – two lines are of equal length Parallel - two lines are parallel Perpendicular – two lines are perpendicular Colinear – two lines lie on the same “virtual line”Line-to-Arc relationsTangent – the line (or its continuation are tangent to the arc/circleArc-to-Arc relationsEqual – the arcs (or circles) are of equal radius – but not length Concentric – the center point of the arcs (or circles) are coincident Tangent – the arc is tangent to another line or circle Coradial – the arcs lie on the same “virtual” circle.Other useful options Fix – at any time you can decide that certain sketch entity would not change when you are moving/changing other entities. To do that – select the entity and press “Fix. The selected line/arc will become black – as it cannot change and is now “completely defined”. For construction – you can define sketch entity to sere only for sketch definition purposes. The Cut/Extrude feature will ignore it – but it can be helpful to completely defining your sketch. Infinite Length – sometimes you would like to set the line as infinite length – and define certain sketch entities relative to it (for instance – angles)– this would of course be the construction line. You actually have 2 unlimited lines present on every sketch – the X and Y axis of the construction plane.
