Rigging a spring?

Since we are using Verge3D, there is another way to do this. Rigging and shape keys take a lot of runtime computation. Why not use puzzles? Use the “Animate parameter from” puzzle to drive the z-scale of the spring.

@ballard, I can’t think of a solution to the cross-section issue. I think that all of the techniques listed in the thread above will cause the cross-section of the spring to ovalize (since they are all a way of z-scaling). There are two techniques that I can think of that may partially hide this issue.
1. Use small displacements. I used +/-25%. Using smaller displacements requires less scaling and causes less distortion.
2. Hide the cut ends of the wire. The cut ends are where the issue is most obvious. If this was a coil for a car, this wouldn’t be too difficult. The spring would be held captive by an upper and a lower spring seat. The spring seat would partially obscure the cut ends

The trick of the shape key method using splines/curves…is once you have your two shape keys created with your curves…is to then convert the curves to meshes. You will have two messhes…squashed and stretched. You then select both and join them when inserting them into their own shape keys. You can then animate the parameters of the shape keys..like a regular animation and use the playanimation or you can set it up to use morph targets..your choice.

Attached are two blend files…the original showing the curves and target and then 1 that has the final shape key used to create the Spring application. Also attached is the spring application.

due to size upload limits, I will post them separately.

spring file with splines converted to curves…with shape keys set and animated.

Good luck