Introduction

Sketching using existing edges in SolidWorks is a powerful technique to create complex and precise models efficiently. It allows designers to leverage geometry already present in their models, saving time and improving accuracy. Whether you want to develop features from existing edges or create dependent sketches that follow the contours of your part, understanding how to sketch using existing edges is essential for advanced CAD modeling. In this guide, we’ll explore how to sketch using existing edges in SolidWorks through detailed, step-by-step instructions, tips, and real-world examples.

Understanding the Concept of Sketching on Existing Geometry

Before diving into the process, it’s crucial to recognize why and when to utilize existing edges for sketching. Unlike starting from scratch, sketching using existing edges can:

• Enable precise alignment with current geometry
• Fast-track the design process
• Ensure design intent and dimensional accuracy
• Facilitate complex feature creation without reconstructing geometry

In SolidWorks, these techniques often involve referencing edges, edges’ projections, or using the “Convert Entities” tool to project existing geometry into a new sketch.

Step-by-Step Guide: How to Sketch Using Existing Edges in SolidWorks

1. Prepare Your Model for Sketching

• Open your SolidWorks part or assembly.
• Make sure the geometry you want to reference is fully defined or visible.
• It’s advisable to rotate or orient your model to get a clear view of the edges you plan to use.

2. Begin a New Sketch

• Select the planar face or flat surface where you want to create your sketch.
• Click on “Sketch” in the Command Manager and choose “Sketch.”
• You can also right-click on a face and select “Sketch” from the context menu.

3. Use the Convert Entities Tool

One of the most common ways to sketch using existing edges is by converting them into sketch geometry.

• After starting the sketch, select the “Convert Entities” tool from the Sketch toolbar.
• Click on the edges, faces, or curves you want to project onto your sketch plane.
• This action creates new sketch entities that are references of the original geometry, maintaining parametric links.

4. Project Edges via the Convert Entities Tool

• Select multiple edges to project complex curves as needed.
• Confirm your selection.
• Click the green checkmark to complete the conversion.
• These projected entities can be used as references for further sketching or dimensioning.

5. Use the Intersection Curve Tool for 3D Edge References

For edges that are in 3D space or on multiple planes:

• Use “Intersection Curve” to create 3D curves from intersections of faces or sketches.
• Access this via “Insert” > “Curve” > “Intersection Curve.”
• Select the faces or sketches whose intersection you want to convert into a curve or edge.
• Use this curve as a reference for your sketching.

6. Create Sketch Entities on the Projected Edges

• Use the converted entities to start your sketch features.
• For example, draw lines, arcs, or points that snap to the projected edges.
• Use “Smart Dimension” to define precise distances from the projected geometry.

7. Add Constraints for Accurate Alignment

• Use constraints such as coincidence, tangent, or parallel to lock sketch entities to the projected edges.
• This enhances the design intent and maintains relationship during model updates.

8. Complete Your Sketch and Use It for Features

• Once your sketch accurately references existing edges, you can proceed with features like extrudes, cuts, or revolves.
• The dependency on existing geometry ensures perfect alignment and precision.

Practical Example: Creating a Cut Along an Existing Edge

Suppose you need to cut into a surface along an existing edge:

1. Select the face where you want to perform the cut.
2. Start a new sketch on that face.
3. Use the “Convert Entities” tool to project the edge you want to follow.
4. Draw a perpendicular or parallel line from the projected edge.
5. Use these references to define your cut profile.
6. Finish sketch and select the “Cut-Extrude” feature.

This method guarantees your cut follows the existing edge precisely, avoiding manual measurements.

Common Mistakes and How to Avoid Them

• Not selecting the correct plane or face: Always ensure your sketch is on the right reference plane aligned with the edges you’re projecting.
• Overusing projected geometry without constraints: Always add constraints to maintain relations as the model updates.
• Ignoring the projective geometry’s dependencies: Remember that projected entities are dependent; modifying the original edge affects all dependent sketches.
• Forgetting to rebuild or regenerate models: After sketching with existing edges, rebuild to verify geometric relationships are maintained.

Pro Tips for Sketching Like a Pro

• Use the “Convert Entities” tool frequently for quick referencing.
• Combine “Convert Entities” with “Entities” from other sketches or features for complex designs.
• Use “Mirror” and “Pattern” features to replicate projected geometry.
• Maintain a clean sketch by removing unnecessary references once final geometry is created.
• Always check your dependencies and relation tree for clarity.

Comparing Different Methods of Sketching Using Existing Geometry

Choosing the right method depends on your specific modeling requirements, surface geometry, and design intent.

Conclusion

Mastering how to sketch using existing edges in SolidWorks significantly enhances your modeling efficiency and precision. By leveraging tools like Convert Entities, Intersection Curves, and strategic constraints, you can create highly accurate features that follow existing geometric references. This skill not only saves time but also ensures your designs are consistent and easily adjustable. Whether you’re creating complex assemblies, detailing features, or doing iterative design work, understanding these techniques will make you a more proficient SolidWorks user.

FAQ

1. How do I convert multiple edges into a single sketch in SolidWorks?

Ans : Use the “Convert Entities” tool and select all desired edges; they will be projected into your active sketch as individual or connected entities.

2. Can I create 3D sketches based on existing edges?

Ans : Yes, using the “Intersection Curve” feature, you can generate 3D curves from face or edge intersections to base your 3D sketches on.

3. How do I maintain references when sketching on existing edges?

Ans : By using “Convert Entities” and applying dimensional or geometric constraints, you keep the sketch linked to the original geometry, ensuring it updates accordingly.

4. What are common mistakes when referencing edges in sketches?

Ans : Common mistakes include selecting the wrong face, neglecting constraints, and forgetting that projected geometry is dependent on the source edges.

5. How can I improve accuracy when sketching on curved surfaces?

Ans : Use “Convert Entities” for the closest approximation plus constraints; for complex curves, consider using spline fittings or intersection curves.

6. Is it possible to create a reference geometry from non-edges, like points or vertices?

Ans : Yes, to create references from vertices or points, you can project them into sketches or use “Pierce” and “Coincident” constraints.

---

By regularly practicing these techniques and understanding their applications, you’ll improve your proficiency in leveraging existing edges effectively in SolidWorks, leading to smarter, more efficient CAD designs.