Modeling a Garter Spring (Simmerring) in Inventor

Stan Wile

While reading the forums at GrabCAD over lunch, I happened upon a question on how to model this type of spring.
Spring 10

There is a method where points are created around a revolved surface torus. Planes are placed about the axis and points on the sectioned quadrants are placed for each rotation. However, for this example that would take hours. Because a spline is then creating by selecting each point. Every rotation is 4 points. That got me thinking of how I would do this if I had to. I started playing around with a better way and settled on this one. My final model is posted here https://grabcad.com/library/ring-spring-1  You can download the model and see how it was created in Inventor.

For those of you without 2020 I will try to explain.

Create a surface torus around an axis. In this example I will use the Y.
Spring 01

Draw a 90 deg arc on the XY plane that runs through the center of the torus.
Spring 08

On the XY plane, project the turus circle and then draw a line from its center to the outside of the circle. This sketch needs to be on one of the end points of the arc created above.
Spring 08

Sweep the line along the arc using a twist of 360 X the number of rotations for 90 degs. (be sure to use 360 X # so that it always ends at the top/bottom so the circular pattern works out.
Spring 08

Start a 3D sketch and use Intersection curve and select the two surfaces. This should give you a single continuous spiral running around the curve.
Spring 08

Turn off the viability of the two surfaces.
Put a plane on the start spline using Normal to a curve at point plane.
Spring 08

On that plane sketch a circle around the start point of the spline.
Spring 08

Sweep the circle along the spline.
Spring 08

Circular pattern around the Y axis 4 times and you should have a continuous spring.
Spring 08

To often we get set in doing something one way, because it works. Quite often there is a better way but we don't take, or have, the time to look for it. If you are interested in digging deeper into Inventor, look over the classes we offer at https://www.imaginit.com/training/find-a-course-and-enroll/find-a-course. Complete outlines are available for each of them. Just click on the Detailed Course Description link when viewing a topic.

With software we typically have the tools in hand, but are unaware of of them or don't know how to use them. Best of luck in your future models and drawings. 

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