Spiral Motion Path

Since I want to have a ball roll down spiral rails in my animation, I did a short test using a motion path to see how it would work. First I made two spirals using the same method as before, then scaled the second one down so it fit inside the first to create the tracks for the ball to roll down. The ball is a simple nurbs sphere that I attached to the motion path and assigned the blinn material to make it appear metal. I made the path itself by selecting one of the spirals, changing it to Isoparm, then duplicating a surface curve. I scaled the curve so it fit between the two 'tracks' correctly and positioned it and the ball slightly above the spirals so the ball appears to roll along them.

Despite how simple the process sounds, I actually found it quite difficult to get everything looking right, especially since the ball always rolled down far too fast and at a constant speed, which didn't look very realistic. I added more frames to the timeline to slow the ball down, then used the graph editor to level out the speed of the ball at the top of the spirals. This made the ball start off rolling slower, then appear to gather speed on its way down. Its still not perfect, but so far I'm quite pleased with the result. I think perhaps the ball still needs to roll a little slower...