What is a ʼSketch Relationʼ (Coincident

Short Answer

A Sketch Relation in SolidWorks defines how sketch entities behave relative to each other. The Add Relations method is the standard professional way to apply a Coincident relation, making points, endpoints, or lines share the same location. It is essential for fully defining sketches. Limitation: Coincident only works on compatible sketch geometry selections.

What You Need to Know Before

Warning: A Coincident relation can over-define a sketch if dimensions or existing relations already control the same entities. This is especially common when users drag endpoints together first, then add Coincident again manually.

How to Add a Coincident Sketch Relation

• Command: Add Relations

• Shortcut: No default keyboard shortcut

• Quick Steps:

  1. Edit the sketch, then Ctrl-select the two sketch entities in the graphics area or from the FeatureManager design tree.
  2. In the left PropertyManager, open Add Relations and review the Existing Relations section if needed.
  3. Under Add Relations, click Coincident, then confirm with the green checkmark.

• Use the fastest common method: preselect sketch entities, then apply the relation from the PropertyManager.

• Real option: check For construction only if you are converting geometry behavior as part of sketch cleanup, not for the relation itself.

Variables & Settings

• Key Setting: Fully Define Sketch / Display/Delete Relations

• Expert Setting: Use Display/Delete Relations to inspect whether a Coincident relation already exists before adding a new one. This prevents duplicate constraints and over-defined sketch states during production sketching.

Why it Fails

• Cause 1 (Geometry): The selected entities are not valid for a Coincident relation, such as incompatible geometry combinations or entities not sharing a meaningful sketch point.
• Cause 2 (layers/Locks): The sketch entity may be fixed or controlled by imported sketch constraints, blocking the intended relation behavior.
• Cause 3 (Command/Logic): The sketch is already fully defined or over-defined, so adding Coincident creates a conflict with existing dimensions or relations.

Quick Fix & Best Practice

• Quick Fix: Use Display/Delete Relations to remove the conflicting relation, then reapply Add Relations > Coincident only to the required endpoints or point-to-entity selection.
• Manager’s Verdict: Use Coincident early to anchor sketch structure cleanly, but avoid stacking it on already dimension-driven geometry in complex production sketches.

FAQ

What does Coincident do in SolidWorks?

It makes selected sketch points or entities occupy the same location.

Can Coincident be added between a point and a line?

Yes, a sketch point can be made coincident with a line or edge.

Why is my sketch over-defined after adding Coincident?

An existing dimension or relation is likely already controlling that same geometric condition.

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