How would you model this? (surfaces)

This is something which represents a real wave washer (compressed and uncompressed), it's a surface loft and thicken.

Thanks for the model.. its interesting that none of the curves in your sketch are used as guide curves.

I'm wondering if that model would still work if the radial lines weren't in the same plane as your base sketch (the ID/OD circles) -- if, say, there were angled away from the origin -- like a cone. (Belleville washer)

I've some playing to do. Thanks again.. very informative.

Model 1/2 of a wave, mirror, then circular array.

How to model 1/2 wave??? Tough question. Make a spline to trace outer edge. Under that, an arc to trace the clock position of your sweep in 2D. Sweep w. guide curve--sweep path is arc, spline is guide curve.

For good measure, make it oversize and then cut the ID and OD with a revolve or extrude. That way you can use OD and ID for mates. Maybe put a tiny flat at the crest of the wave.

Attempt to make flats at wave crests would not resolve in sweep. Otherwise, as advertised. Linked values in equations folder for easy adjusting.

Well,.. not quite sure what you going after but here's something for now on creating a angled wave washer?

Having a guide curve in this case is not going to gain you much or get it much closer to the od/id but if it's needed you can create a cone surface and sketch a spline on surface (guide curve) on the cones surface (od/id), connect at each section corner to maintain your cone/ diameter intent?