Strange phenomenon with IK

Hello Blender users,

I’m a very (french) beginner with Blender and I’m trying to apply Inverse Kinematics on legs of my model (something which looks like a cat…)

My problem is that after having created an IK bone (at the lower extremity of the leg, as said in a video tutorial) and after applying an IK, my armature become like this:

After that, when I try to displace the IK bone, the leg does really stranges and uncontrolables moves…

Did somebody ever see something like this or am I just going straight in a wall?

Thank you in advance for your help!


I’ve had some buggy build of Blender that has caused a similar problem. Would you share your .blend file so that we may hunt the problem down?

there it is ! .blend put in attached file.

For information, I use Blender 2.58.


cat_armature.blend (605 KB)

Ok, this is what I think is the problem. When you created your bones you didn’t keep “Inherit Scale” on and if you turn it on on all your bones you can see how crazy you have made everything. I would start over and keep inherit scale on, scaling the children bones in pose mode as needed for your viewing pleasure. Remember you can use custom bone shapes so scaling like you are doing doesn’t have to be.

After I reset all of the bones and turned on “Inherit Scale” for all the bones the IK setup worked fine.

Thank you very much for your help ! It works now I have reseted all the scales.

I just don’t understand what modifying a bone’s scale in Edit mode is for?