When i try to rotate the hand bone in the z axis in the rest pose (of the bone itself) it works as usual, but i setup some copy rotation constraints that are attached to each twist bone from the hand to the last twist bone, and each twist bone is parented to the forearm, because if they are parented as a chain to each other, the copy rotation constraints don't work properly and a dependency cycle comes out, which was caused by the parenting, so they cant be parented to each other like a chain, they must be separated from each other but parented to the forearm like i did...

So if i try rotating the y axis of the hand bone to get the arm twist bones to work and then later try to rotate the z axis down or up of that hand bone, the rotation doesn't go right, the z rotation affects the y causing to rotate both axis with no reason, this issue doesn't happen with the x axis, the x axis is working as it as it should, but not the z axis, i checked that the rotation mode is quartenion in all bones, i attempted with euler mode but i get gimbal locks... here is the simple ik arm setup if you want to check the issue...please upvoting this post and giving answers are appreciated, thanks. Michael.

  • 1
    $\begingroup$ hello, it sounds a bit complicated, what are you trying to achieve at the end? At first I thought your forearm was one unique bone that you had segmented, why didn't you do that? $\endgroup$
    – moonboots
    Oct 19, 2020 at 7:04
  • $\begingroup$ hello bud, because without the forearm, it doesnt deform properly like an 3 segment arm should, that why it should be parented to the forearm, and then the hand,forearm and upperarm works as usual, and the twist bone are an additional setup that deforms the mesh, but since you really cant have two or more bones with of 1.000 of weight in the same vertex group that is already parented to another vertex group (i.e the whole forearm and 4 twist bones sharing the same parts of the same vertex group ) like this producing a vertex parenting issue, thus problems to deform properly, so here... $\endgroup$ Oct 20, 2020 at 5:27
  • $\begingroup$ ....what should be done, is to clean the vertex group from that forearm and uncheck the deform option of the bone, thus letting the twist bones to work properly, but at the same time still driven by the forearm parent...imagine this same setup with the the same segmented bones, but with this additional forearm bone, but this twist bones work as the forearm, well you cant if you are using ik, if they were all together as a chain except the hand target, the segmented forearm would bend unexpectedly because that how ik works, but they can be limited in the ik properties of each bone... $\endgroup$ Oct 20, 2020 at 5:27
  • $\begingroup$ ....but it would lose sense to me, to do that because its not meant to be setup in this way...also i did the same with fk mode bones and its the same problem, i am thinking this its a rotation limitation here, but i dont know thats why i need answers.... i am using b3d 2.82a just in case... $\endgroup$ Oct 20, 2020 at 5:28
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    $\begingroup$ hello Michael, your explanations give me headache, ah ah, but I'll try to find time to check, or maybe someone will help, or maybe reformulate what you want to do (your final goal), with some drawings, so that people start from scratch and not from your file? $\endgroup$
    – moonboots
    Oct 20, 2020 at 20:06


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