Create a Helix or Spiral in FreeCAD Part Design

This guide explains how to model helical and spiral features in FreeCAD Part Design, covering both the native Additive Helix tool for generating solid objects like springs and threads, as well as the workflow for creating standalone wire curves to use as sweep paths.

Method 1: Using the Native Additive Helix Tool (Solids & Features)

The most direct way to create a helical solid inside the Part Design workbench is by sweeping a sketch profile directly along an internal helix engine:

  1. Create an Active Body and Sketch: Open the Part Design workbench, click Create body, and then Create sketch. Select a plane perpendicular to your intended path (such as the XZ or YZ plane).
  2. Draw the Cross-Section: Draw the 2D profile of the object (for example, a circle for a coil spring or a trapezoid/triangle for screw threads). Constrain the distance between the profile and the central axis, as this distance defines the radius of the helix. Close the sketch.
  3. Apply the Additive Helix: With the sketch selected, click the Additive Helix icon (or go to Part Design > Create an additive feature > Additive Helix). For cutouts like internal threads, use the Subtractive Helix tool instead.
  4. Configure Helix Parameters: In the Tasks panel, adjust the following properties:
    • Axis: Choose the axis of revolution (e.g., Base Z axis, a datum line, or a sketch axis).
    • Mode: Select how dimensions are calculated (Pitch-Height-Angle, Pitch-Turns-Angle, Height-Turns-Angle, or Height-Turns-Growth).
    • Pitch and Height: Set the distance per revolution and the total length.
    • Angle (Cone Angle): Set an angle greater than zero to create a tapered, conical helix.
    • Growth (Spiral): Use positive growth values to expand the radius per turn, creating a planar or volumetric spiral.
  5. Confirm: Click OK to generate the solid.

Method 2: Creating a Standalone Helix or Spiral Curve (Sweep Path)

If you need a 3D helix or flat spiral curve to serve as a custom path for the Additive Pipe tool, you must generate the primitive curve and bind it into your Part Design body:

  1. Create the Primitive Curve:
    • Switch to the Part Workbench.
    • Click the Create primitives tool (yellow geometric shapes icon).
    • In the dropdown, select Helix or Spiral.
    • Enter your parameters (Radius, Pitch, Height, or Growth for flat spirals) and click Create, then Close.
  2. Bring the Curve into Part Design:
    • Switch back to the Part Design Workbench.
    • Ensure your Body is active (double-click it in the tree if it is not bold).
    • Select the helix or spiral curve from the tree view.
    • Click Create a sub-shape binder (green outline icon). This imports an active reference of the curve into your Part Design Body.
  3. Sweep Along the Curve:
    • Create a new sketch for your cross-section profile on a plane located at the start of the curve.
    • Select the profile sketch and click Additive Pipe.
    • In the Tasks panel, click Path, then select the sub-shape binder curve in the 3D view.
    • Click OK to sweep the profile along the spiral path.