Sketch menu: Extend tool

What is the Extend tool?

You can use the Extend tool to lengthen sketch lines and arcs until they meet another curve. Extend follows the existing direction of a line or the curvature of an arc, stopping at the nearest intersecting curve along the extension path.

Extend works with existing sketch items, allowing you to connect geometry and close gaps without redrawing lines or arcs.

How to use the Extend tool

To extend a sketch line or arc:

1. Go to Sketch > Extend.
   For other ways to access tools, visit Accessing tools.
2. Hover over or move toward the line or arc you want to extend. The preview shows where the extension will meet another curve, when a valid intersection is available.
3. Select the line or arc. Extend uses the endpoint closest to your selection and extends it to the nearest intersecting curve.
4. Optional: Select the extended curve again to extend it to the next intersecting curve.
5. Continue selecting sketch items as needed.
6. To finish and exit the tool, select an empty area of the modeling space.

How Extend handles sketch geometry

Extend follows the shape of the selected curve and uses existing sketch geometry to determine where the extension stops.

Extending lines

A line extends in its existing direction until it meets the nearest intersecting curve. Its opposite endpoint remains in place. The extended endpoint stays connected to the curve it reaches, even if that curve is modified later.

Extending arcs

An arc extends along its existing circular path, maintaining the same center and radius. If it does not encounter another curve along its remaining circular path, Extend converts it into a complete circle.

Supported sketch geometry

• Lines – Extend along their existing direction until they meet another curve.
• Arcs – Extend along their circular path while maintaining their center and radius.
• Construction geometry – Construction lines and arcs can be extended and can serve as boundaries.

Splines, circles, and ellipses cannot be extended, but they can serve as boundaries for supported curves.

Constraints and limitations

Extend preserves existing sketch constraints and connections. A constraint that prevents an endpoint from moving can block an extension.

• Nearest intersection – Extend stops at the first curve intersecting the extension path.
• Existing boundaries – The extension stops at an existing curve, not where that curve would intersect if it were longer.
• Collinear lines – When another line lies directly ahead on the same path, Extend stops at its nearest endpoint. The lines remain separate.
• Constrained endpoints – Locked endpoints or constraints that prevent a change in length or shape may block an extension.
• Connected endpoints – Endpoints connected to multiple sketch points cannot be extended.

History settings

Shapr3D records sketch items created on the same plane in a shared Sketch step in History. Find the Sketch step to review or modify these settings:

• Plane – Select Edit… or Select… to change the plane or face containing the sketch, then select Done.
• Projection – If applicable, select Edit… to modify existing projections in the sketch.

When to use the Extend tool

Use Extend to refine existing sketches, including:

• Closing gaps – Lengthen a line or arc to meet another sketch curve and complete a profile.
• Connecting outlines – Bring separate sketch items together without redrawing them.
• Adjusting boundaries – Extend lines to existing edges or construction geometry used as references.
• Refining curved profiles – Continue an arc along its circular path until it reaches another curve.

Best practices and troubleshooting

• Select near the endpoint you want to extend to control the extension direction.
• Check the preview before selecting a curve to see the proposed intersection.
• Review sketch constraints if the geometry cannot be extended.