# Constructing Splines

A Spline is a smooth curve that is fit to a set of points. You can create a non-uniform rational B-spline or NURBS curve for any number of fit points. You can also fit the Spline to the specified points within a specified tolerance value.

To construct Splines:

- Click
**Draw > Spline**(or type**Spline**). - In the graphics area, click to define the:
- Start point of the Spline or enter a value.
- Next fit point of the Spline or enter a value.
- Do one:
- In the graphics area, click to enter successive points to continue the Spline.
- Specify the
**Fit tolerance**option to define a fit tolerance and click or enter other spline points. - To conclude the Spline, do one:
- Press
**Enter**and click in the graphics area to define the tangents at the start and end points of the curve. - Specify the
**Close**option to close the Spline curve and click in the graphics area to define the tangent to the curve at the closing point.

After you specify a fit tolerance, the fit tolerance applies to all fit points until you change it. Setting the fit tolerance to zero forces the Spline to pass through the fit points.

**Note**: You can use EditPolyLine to convert a PolyLine to a Spline.

Access

**Command: Spline**

**Menu: Draw > Spline**