Animation newb question...

I am animating a rotating propeller. I addded a keyframe at frame 1 then another at frame 10 and rotated the propeller 45 degrees then chose extrapolation in extend mode to have the propeller continously spin for the whole 10 second animation. I need the propeller to slow down to a stop in the last 2 seconds of the animation but I am having trouble when it comes to adding another keyframe in the IPO editor, I can make it come to a dead stop but not ramp down slowly.

try manually adding a Speed IPO curve along with your extrapolated Rot curve. Use the speed IPO to control the overall speed of the animation down to 0 at the end.

@ DM : How do you add a Speed curve on an object that isn’t a curve/path? …

You can’t use the extrapolation extend mode to do this … You have to manually key the rotations/slow down/stop along a single curve … but you can’t do that directly with say the Z axis on your propeller since trying simply add a slow down/stop key(s) will reverse the rotation of your propeller … which is not what you want …

Instead what you can do is to use a proxy (like an empty), add an extrapolation extend mode rotation to it, and add a copy rotation constraint on the propeller and key the constraint influence with start/rotate/slow down/stop keys …

Here’s a simple blend example (you can add more keys to make the start/slow down smoother) :


proxy_rotation.blend (147 KB)

My bad, I meant to add a time IPO not speed. Shouldn’t a Time IPO be able to slow down the extrapolated IPO?

It’s only 10 seconds, just keyframe the entire animation. Forget the extrapolation mode. Sounds like you only need 3 keyframes to make this animation.

What you can do is look at your existing curve in the IPO and scrub out to 8 seconds. The extrapolation curve should show you what the aproximate ROT value is for your prop at 8 seconds. Just turn off extrapolation and add a keyframe there at 8 seconds. Then you just need another final key frame to slow it down.

Thanks for all the responses. My mistake, the animation is 35 seconds long with the slow down and stop happening in the last 8 seconds. I am attaching the blend so you can see what is actually taking place.

I am kind of new to Blender and learning what I can from tutorials and web docs but I am kind of lost when it comes to the IPO editor.