In the process of making this mechanical hand I am trying to add a small piston that pivots on the fingers. The issue I'm having is that the part of the piston that joins to the finger is curved and whenever I rotate the finger the part that is supposed to pivot clips through the mesh.piston pivot point The piston itself functions properly with one side pivoting on a ball joint and two damped track bones that facilitate the function. The problem is where the curve starts and attaches to the second pivot point around the finger. Things I have also tried is rearranging the bones and cutting the mesh into separate pieces where I have gotten this part to pivot properly but either the piston wont line up anymore or some part of the mesh becomes distorted when its supposed to remain solid.pivoting properly but no longer lining up & Mesh distorting after attempting to cut into separate pieces and parenting Normally I don't have issues like this as long as my objects remain straight but adding this curve to my object while considering all the mechanisms confuses me as to how the bones should be placed inside the object and what pieces should be parented to what part of the mesh. Video of my issue & Project file

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1 Answer 1


At first, let me suggest you not to create 100 armatures: it's better to deal with one single armature object with 100 bones in it. If not, when animating you'll have to deal with 100 different actions, while Blender structure is well organized to deal with a single action, applied to a single armature, controlling 100 bones.

So, select the Rotor bone/armature, go to edit mode and add (Shift A) the four bones in the picture (A,B,C,D).

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A is child of Rotor (Keep offset)

B is child of A (connected)

Rotor, C and D will be child of a hand bone (not present yet)

B has an IK constraint, targeting D, chain lenght 2 (in my example the name of D is "Target2").

C has a damped track constraint targeting B.

Select B bone and set its IK properties as rigid joint, limiting its X Y and Z rot from 0 to 0 degrees (you cannot use a limit rot constraint here, because IK is calculated last).

Then animate the Rotor bone.

enter image description here

enter image description here


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