Alibre Options: Linking Helix Features for More Accurate Spring Representations3 Feb, 2006 By: Michael Todd Cadalyst
The Project to Sketch tool provides a simple solution to link helix features.
Recently I was asked how to create a spring that transitions from a constant pitch to a varying pitch. The simple, but perhaps not so obvious, solution is not to link two existing helix features, but to create one based on the other using the Project to Sketch tool.
- In Sketch mode sketch a circle and a reference line on the y-axis. The reference line will serve as the axis that the helix will revolve around.
- Click the Helix tool, use the following options; then click OK.
- Select Sketch<1> for the sketch and the reference line for the axis.
- Change the type to Revolution & Pitch.
- Change the pitch type to Variable Ratio.
- Enter 4 for the revolutions, 1.0" for the pitch and 2.5 for the ratio.
- Create an angled plane by going to Insert / Plane. Choose a plane (xy-plane) and an axis (y-axis). Type in small angle (-3.000?) in the Angle text box.
- Click on the plane that you just made and go to Sketch mode.
- Sketch a rectangle that is greater than the profile of the helix.
Figure 1. Use the Extrude Cut tool on the sketch on the new plane.
- Click the Extrude Cut tool and make sure that you cutting off only the end of the helix.
Figure 2. The end of the helix is trimmed at a precise angle.
- Click the Project to Sketch tool, choose the face of the helix that you just cut, and click Maintain Association to Source Entity. This option will maintain the same radius throughout the helix.
- Sketch a reference line and click on the Helix Boss tool.
- Change the following options, and click OK.
- Change the type to Height & Revolution.
- Type in 4.0 for height and 7 for revolutions.
Figure 3. The completed spring has the parameters of both helix operations.
Repeat these steps as needed to create a representation of a spring with any number of variations.
Autodesk Technical Evangelist Lynn Allen guides you through a different AutoCAD feature in every edition of her popular "Circles and Lines" tutorial series. For even more AutoCAD how-to, check out Lynn's quick tips in the Cadalyst Video Gallery. Subscribe to Cadalyst's free Tips & Tools Weekly e-newsletter and we'll notify you every time a new video tip is published. All exclusively from Cadalyst!