hopefully I don't ask the same thing the thousands time, but here is my problem:

Start of Animation with Keyframe 0


Middle without Keyframe


End of Animation with Keyframe 400


In the middle I get this Gap:


I would like to rig it so that I can grab Arm_1 or Arm_2_Lever and it does the mechanical correct movement. You can see the parenting on the Left of the pictures. I already tried parenting Arm_2 to Arm_2_Lever and stretch Arm_1 to Arm_2_Lever.control. But with that the base of Arm_1(left side in the start of the animation) stays at its position.

Thanks M


1 Answer 1


The real reason that bone has pulled away has to do with set-up. this rigging is based on 'pythagorean theorem' or more in the case of 'Parallelogram law'. So, as far as your issue is concerned, that needs to be addressed first. Using a 'stretch to' constraint will leave your part 'stretching', which is un-real in mechanical rigging. I would use a 'Damped Track' constraint instead or even an IK. As far as getting the whole thing to move just using one control bone, that would be the job of an IK constraint. You could extrude a bone off of 'Arm_3', un-parent it and parent it to the 'Root' bone, give 'Arm_3' the IK targeting the new bone, chain length = 3. Lock the IK locks (Y & Z) of all 3 bones in that chain, transform lock 'Rot','Scale' & 'Z Loc' of the 'IK target' bone. Set all bones rotation mode to 'XYZ', no need to use 'Quaternions' here. If you need more help, PM me (AJCDFIN) over at BAHere is a pic illustrating your rigs real issue. Euler's quadrilateral

  • $\begingroup$ Hi, Thanks for the answer. Unfortunately does the Dampend track constraint has the same effect, only that I don't need to switch of the mesh deformation like in the stretch to constraint. The Arm_2_Lever Bone points to "arm_2_lever.control" but is not "connected". The same happens when I insert an IK-Bone. If I extrude an IK Bone from the tip of Arm_2 and make it rotate around the tip of arm_2_lever, that would help! But Pivot does not work somehow. I tried to extrode a little bone out of arm_2_lever and make the IK-Bone at the tip of Arm_2 rotate around it. $\endgroup$
    – M.Hoppe
    Mar 4, 2020 at 22:31

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