2D Splines are used to draw shapes with compound radii. Typically, geometry containing compound radii is more expensive to manufacture than geometry drawn with straight lines and tangent arcs, so I recommend that you avoid using them whenever possible.

For those special circumstances when you need to draw complex geometry, this exercise will show you how to draw and reshape a 2D Spline. Subsequent Tips and Tricks will show you how to take control of your splines by mastering all the commands associated with them, and learning how to constrain them.

There are many powerful commands and drawing procedures you can use while you draw 2D Splines. In this short exercise you will draw an arc, move and adjust it, and then convert the arc to an elliptical shape.

Draw a Spline
The first step is to draw a spline. Click the down-arrow next to the Line command, and then select Spline.

Now you’re going to draw an arc by selecting 3 points. Click the first point to start the spline, click the second point about in the middle of the arc, and then double click the third point to finish drawing the arc.

Type the escape key to exit Spline mode.

Adjusting a Spline
To move the spline, place your pointer over the curve and drag it to a new location.

To adjust the shape of the spline, place your pointer over a spline point and drag the point to a new location.

You can drag any spline point to adjust the shape.

You can also adjust several spline points at once by holding the Alt key down and dragging a spline point. When you do this, Inventor will attempt to keep the same general shape of the spline while moving the points.

Creating a Loop
You could have created a looped spline by clicking three points, and then double clicking the first point. Since you’ve already drawn the spline, you can create the same loop by right clicking the spline and selecting Close Spline.

In the next Tips and Tricks called Constraining Splines you will add a Spline Point, and then use Construction Lines to gain more control over the shape of the spline.