Sketch menu: Spline tool

What is the Spline tool?

You can use the Spline tool to create smooth curves for rounded profiles and organic shapes. Choose one of two spline types:

• Fit Point – Creates a curve that passes through the points you define. Moving one point can affect the shape of other parts of the curve.
• Control Point – Creates a curve guided by a control polyline. Move its control points to shape the curve without dragging the curve itself.

How to use the Spline tool

Create a Fit Point spline

1. Define your sketch plane.
2. Go to Sketch > Spline > Fit.
   For other ways to access tools, visit Accessing tools.
3. Create the curve using your input method:
   • Keyboard and mouse/trackpad: Click to place points that the curve should pass through. Continue placing points to shape the spline.
   • Touch and pen: Draw a curve segment, then lift your pen. Start from the previous segment's endpoint to draw connecting curve segments.
4. To finish drawing with a mouse or trackpad, press Escape or Backspace. With a pen, lift your pen to finish the current segment.

Create a Control Point spline

1. Define your sketch plane.
2. Go to Sketch > Spline > Control.
   For other ways to access tools, visit Accessing tools.
3. Place successive control points to create a connected control polyline that guides the curve:
   • Keyboard and mouse/trackpad: Click to place points along the control polyline.
   • Touch and pen: Draw connecting lines to form the control polyline.
4. To finish drawing with a mouse or trackpad, press Escape or Backspace.

Edit a spline

After creating a spline, you can change its shape by editing its points.

• Move points – Select and drag a point to reshape the spline. With a mouse or trackpad, exit the Spline tool first by pressing Escape. For a Control Point spline, move the control points rather than the curve itself.
• Adjust Fit Point curvature – Select a fit point and drag its handles to change the curvature at that point.
• Add points – With a mouse or trackpad, right-click the curve to open the context menu, then select New Spline Point. With a pen, select the curve and long-tap it.
• Remove points – Select a point and choose Delete.
• Break or join splines – Select a point and use the Break/Join badge. For more about sketch relationships, visit Constraints.

Tip: To create a tangent connection between a Control Point spline and a straight line, align the spline's control polyline with the neighboring line at the connection.

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 Spline tool

• Trace a particular path – Use Fit Point splines when the curve needs to pass through specific locations.
• Shape smooth outlines – Use Control Point splines when you want to adjust the overall flow of a curve through its control polyline.
• Create organic profiles – Use either spline type for flowing shapes that are difficult to construct from straight lines and arcs alone.

Best practices and troubleshooting

• Choose the spline type based on how you want to edit. Fit Point splines pass through their points, while Control Point splines are shaped by a guiding polyline.
• Adjust the appropriate points. Move fit points and their handles for a Fit Point spline; move the control points for a Control Point spline.
• Check neighboring geometry. When joining a spline to another sketch item, review the connection and any relevant constraints.