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A problem I always have with my characters are their wrists. I can't figure out a way on how to rotate the hands withouth breaking the wrists and the arms. Here is what I mean:

Here is the Arm on it's normal pose:

Normal Pose

And this is what happens when I rotate the hand:

enter image description here

See what happens? Everytime I try to rotate the hand a bit too much that happens, and I got no idea on how to fix that. Why does it even happen? And how can I fix it?

Here is the blend file:

https://mega.nz/#!wB9BjZSZ!1VC-AZtuYLzuZLBQXDR71iGe5-ccKG8MpKoFyxTJbXw

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  • $\begingroup$ You should consider rotating the arm and not the wrist. If you look at your hand and try to rotate it, you will discover that it's not so much the wrist but the entire forearm that rotates. $\endgroup$ – Shady Puck May 31 '16 at 21:00
  • $\begingroup$ It doesnt really work because of how I IK the arms of my characters. Is there a way of doing that while keeping the IK? $\endgroup$ – Pherion May 31 '16 at 21:02
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Rotate your own hand and you should see the answer ;-)

When the "wrist" rotates, the wrist joint itself doesn't actually do any rotation. When you turn your hand over, it's your forearm that does all the twisting, mostly at the elbow. The solution is usually to have a wrist bone that also influences a great deal of the forearm, as well as the hand. Depending on how detailed you want to be, you might even consider multiple forearm bones that each rotate only a little so that the whole arm can twist.

Think about the movement of the two bones in your forearm, and it's really quite a complex motion you're trying to recreate.

I'm really surprised that I couldn't find a tutorial on this topic. I may have to create some more detailed instructions when I get home.

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  • $\begingroup$ I know. I first tried looking around for a tutorial, but there is nothing about it. I would really appreciate if you could make a tutorial. And yes I have looked at my own Arm, and what really rotates is the Arm not really the hand. But I'm not sure how to apply that along with the IK. :\ $\endgroup$ – Pherion May 31 '16 at 21:35
  • $\begingroup$ You should add a copy rotation constraint on the hand and and make the target the ik handle. The hand will twist some, but then you can rotate the hand and move the arm with the ik handle. $\endgroup$ – Nolan May 31 '16 at 21:59
  • $\begingroup$ +1 to counteract the -1. The answer given is in good faith, does potentially help and also promises more at a later point. Even if it isn't the answer you wanted, it didn't deserve a -1. Also, for future reference, downvoting answers that don't help makes people far less likely to answer your questions. $\endgroup$ – IchabodE May 31 '16 at 22:36
  • $\begingroup$ I've already done that. And it's still the same. :\ $\endgroup$ – Pherion May 31 '16 at 22:42
  • $\begingroup$ I didn't gave it a -1 :\ $\endgroup$ – Pherion May 31 '16 at 22:43
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I think the simplest solution would be to give the "ForeArm.R" bone a "copy rotation" constraint, make it follow the rotation of the wrist, but reduce the influence to maybe 50%

https://gfycat.com/TastyDampAlpineroadguidetigerbeetle

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Another possible solution is to create a shape key that model the perfect shape you want when the hand is rotated 180 deg. Then you can add a driver so that when the hand bone rotates the shape key enters in action.

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