Animating Crane Arm Rotation Completely Screws Everything Up


I am trying to animate the rotation of an extremely simple crane arm that is lifting something. I put the 3d cursor where I want the arm to rotate from, I put it in Local mode, I select the arm, the wire, and the object it is lifting, I hit i to set initial keyframe for locrotscale, then I step forward through the sequence, then I rotate the arm pivoting from where the 3d cursor is. Everything is in the position I wanted it to be in and when I rotated the arm manually, it moved exactly like I wanted it to. So I hit i to set another locrotscale. Everything looks fine. And then I start stepping backward.

And now the entire scene is break dancing. The whole thing goes crazy!!! The positions at the keyframes are correct, but the path it takes to get there is absolutely ridiculous. And this doesn’t effect just the space in the sequence in between the two keyframes I just made, it completes screws up the path in between the keyframes before it as well. All the objects separate, they take a completely ridiculous path, and then end up where they are supposed to be.

I just need the animation path to follow the same path it followed when I rotated it manually. Is that too much to ask?

I know it has to be something about the local/global/normal thing or something like that, but I experimented with all sorts of combinations of those settings and different types of keyframes (loc, rot, locrotscale, delta, visual, etc.)

I feel like maybe this is a case where you need bones and an armature and all that, but it really is an incredibly simple thing I am trying to do.

Help, anyone?

Try to avoid keyframing rotation about a cursor (or about anything at all that isn’t the rotating object’s origin.) This looks like just rotation, but it’s really a combination of rotation and translation, and it’s not going to interpolate well. Especially if you’re doing it with multiple objects, like it sounds you are. If you can’t rotate about an object’s origin, create an empty at the center of rotation, parent the object(s) to the empty, and rotate the empty.

If you’re still having trouble, you might consider changing the empty to use a quaternion transformation, as Eulers can give some pretty crazy interpolation at times.

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this is a sentence.