Detailed Drawings > Working with Drawing Sketches > Sketching in Drawing > To Create a Spline in a Drawing
  
To Create a Spline in a Drawing
1. Click Sketch > Spline. The Snapping References dialog box opens. Use the arrow icon in the dialog box to add any references you want to set up before you sketch.
2. Click to define a start point and then any number of interpolation points to define the spline.
3. To end the spline at the last selected point, press the middle mouse button.