Spin the Fan Using SU Animate

SU Animate enhances the power of building animations in SketchUp. We can create Path Animations in SU Animate, as well as the built-in functions for Scene Animation in SketchUp. To play the animation in SketchUp, we simply use the command Animation>Play.
But of course, we can also output the scenes as a collection of .skp files, render them, and string them up, to create a high quality movie clip.

A Spinning Fan

To make a fan spin, we don't even need the new features from SU Animate 2.0 -- the current version is capable of doing that. It's not a difficult task, so here I will take the fan model from my previous assembly animation tutorial as an example.
First, I group up the fan blades and give it a name, say "FAN".
Then I draw a circle in front of the fan body, to be the movement path of the blades. Note that the center of this circle has to be align with the center of the blades, and also mind its direction, as a fan always spins clockwise.
Next, I divide the circle into 6 segments, use the command from SU Animate to create a path from them, and assign it to the group FAN.
Last, I use the command from SU Animate to build up 7 scenes, and it is done.
To play this animation, we first go into View > Animation > Setting, to set both Scene Delay and Scene Transition as 0, and then click on Animation > Play.
I am attaching the complete .skp file at the bottom, so you can download it give it a try by yourself.

How Fan Blades Really Spin

However, that was a bit naive. Anyone ever used a fan knows that when we turn on a fan, rather than moving in a sudden, it will smoothly accelerate from stop. In fact, this phenomenon applies to most mechanical devices, for examples, vehicles.
Since SU Animate does not provide a way to set varying frame rates within an animation, I have to tune the blade spinning speed by building the frames manually.
Since this fan has 3 blades, this time I create a path with 24 segments, and use the "Make Batch Files" command from SU Animate to output the .skp files.
Due to symmetry, the last 16 files are actually redundant, so I use Podium 1.5 to render the first 8 .skp files into 800x600 JPEGs, to be the frames of my animation.
Since the blades are the only moving parts of the fan, these frame are enough to create the entire animation. The logic of spinning speed is simple: the greater angular difference of blade positions in adjacent frames, the faster they spin in the animation; and vice versa.
Hence I create this 9 second long animation using the 8 rendered JPEG images. Thanks to the rendering work, which removed the borderlines of objects (edges) in SketchUp, the image looks actually pretty refined.
This piece of animation has demonstrated a fan spinning at a varying speed, which accelerates from stop, decelerates, and then finally stop.

This animation was shown upper, by bianhai
He is so kindness.