compressed spring

You have to make the spring dynamic by constraining it, Probably equations tied to it's height. And create it using rev count. I beleive Mike Wilson has an example

There is an example of using a spring in an animation in the download area of the Colorado SolidWorks User Group website, cosug.com

Thanks to both of you for your help and the websites. Hopefully, I can figure it out.

I have a couple of springs that can be easily used for animations.

The links below will allow you to download the compression spring, and an extension and torsion spring I had laying around. The models are for education on modeling strategy only - I did not look up any springs for

real, nor did I take a ton of time to clean up the models the way I would if I was doing them for a customer/delivering to a customer.

By the way, the compression spring is kind of cool because it shows a trick for getting equations to evalaute betwen frames in an animation. I needed the spring to be equation driven so anyone could use it to add coils, change diameter, etc without doing a lot of reconstruction. The spring I did a few years ago used equal sketch relations to flex the spring, so it would be a lot of work to make any change. I figured I ought to beat the limitation if I was going to share it.