what is the differance between FK and IK bones?

hi everyone!
a while back i saw a video and the guy used an FK bone or something like that but it looked like it did the excact same thing as an IK bone. what’s the differance?

FK Movement involves moving the bones one by one while IK movement is controling a chain of bones by controlling a IK bone.

you can turn on “auto IK” even on FK bones. Not sure of your understanding of IK/FK, but I’ll try…

IK sets a target - say your foot, planted on the ground. As you move your hips, the foot stays in position, the thigh and shin move to make it so.

FK, say for the arms. You move your upper arm, then lower arm and your hand goes where it will. With “auto IK” you can move your hand to position, but if you move the hips, the hand will move too, it’s not anchored to anything, the upper and lower arm will not compensate…

Hope that made sense.

yes. thanks for that!:yes:

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how do you fix a bone in position when it’s in an IK ie I want to stop a character’s hand from moving about when the rest of the body and upper arm is moving, because it’s resting on the characters leg

well, for something like that, Usually I have a bone (hand_IK.L/R) which is positioned on the thigh, if the thigh is not moving, I would have the hand_IK unparented to anything, if the thigh moves, I would paretn the hand_IK to the thigh. Then I have the forearm with an IK constraint pointed to the hand_IK. and the hand itself, a copy rotation constraint to hand_IK.

i had that same problem. thanks!