# Helix Curve

Create a helix (or a spiral if the top and bottom radii are different).

1. On the Geometry ribbon, select the Helix tool.

Note: The tool may be hidden in a dropdown menu. To access the dropdown menu, you can do one of the following:
• Click and hold the currently displayed tool (NURBS).
• Select at the lower right corner of the currently displayed tool (NURBS).
The guide panel appears.
2. Create the helix:
• Click and drag to place the axis origin and define the diameter.
• Move the cursor to adjust the height, and then click to complete the helix.
3. Choose a helix Type. Note that modifying the height, pitch, or turn is type dependent.
• Turns and Height (default): You can modify either the number of turns or the height, while keeping the pitch constant.
• Turns and Pitch: You can modify either the number of turns or the pitch, while keeping the height constant.
• Height and Pitch: You can modify either the height or the pitch, while keeping the number of turns constant.
To Do this Note
Change the height
1. In the guide bar, select Method: Height/Pitch or Method: Turns/Height.
2. Do one of the following:
• In the guide bar, enter the Total Height.
• In the modeling view, drag the straight arrow.

Change the pitch
1. In the guide bar, select Method: Height/Pitch or Method: Turns/Pitch.
2. In the guide bar, enter the Pitch.
Change the number of turns
1. In the guide bar, select Method: Turns/Height or Method: Turns/Pitch.
2. In the guide bar, enter the number of Turns.

Change the direction In the Control Panel, select a Reference Direction:
• Global X Axis
• Global Y Axis
• Global Z Axis
• Reference Geometry: In the modeling window, click a reference object.
• Custom: In the modeling window, drag one of the arrows for rotation.
To invert the current direction, click Invert Direction.
Create a spiral You can turn the helix into a spiral by making the top and bottom diameters different.
1. To unlock the diameter ratio, in the modeling view, click the lock icon.

2. Select the top or bottom diameter, and then drag to resize it or enter a value in the Top Diameter or Bottom Diameter text box.

Change the spiral pitch In the Control Panel, enter a Spiral Pitch.
Change the direction of the helix (clockwise or counterclockwise) In the Control Panel, turn on Reverse twist.
Move the helix Drag the Origin. Alternatively, to use the Move tool, exit editing mode first and make sure the helix is selected. When using the Move tool, the center corresponds to the center of the bounding box instead of the axis origin.
4. Right-click and mouse through the check mark to exit, or double-right-click.