So, I want to rig an “Arm” and a gear that moves counter to the bending of the Arm, i.e. give the illusion that the gear is moving the arm by turning. I managed to get the [Cog] Bone to move as I desired with a Copy Rotation Constraint and a little finaggling (See Bhelp1), but as I move [Upper Arm] the Cog is no longer aligned. I need to use some tracking constraint, but be it locked track or Damped Track I either get it to point and align, but loose the Copy Rotation or it doesnt work at all anymore.
Does anyone with more experience have a solution? Do I need to add another Bone?
I was always terrible with rigging and want to improve and constraints keep breaking my head. I assume the answer is not too complicated, but I cant manage by myself. Any Advice, Help or Recommendation is very much welcome.
This is my first post here, I have asked the question on r/blenderhelp but havent gotten an answer, if anything here breaks the rules of the forum please be kind and I see to fixing/removing it.
Edit: Here is the Blend file in a separate file, though the problem is still happening.
I added some mesh to the bones to illustrate the problem a little better.
You actually need to supply better/more information, and the .blend file too. Since you are new here, you probably can’t attach a file to this post until you have a few more posts. It’s anti-span thingy… So post the file on a file hosting site and post the link to it here.
Your Cog bone can only rotate on the axis I’ve drawn in with a yellow line. Normally, an upper arm-lower arm joint only rotates on 1 axis. The Cog bone doesn’t match any single axis that the elbow joint can rotate on.
So I’m confused as to what you are trying to do. Show me what the entire arm looks like. Better yet, upload the file with the arm in it so someone can see what you have going on.
I am currently not able to post more than a single picture, that is likely why the picture is confusing you.
When the whole armature is pointed towards the z axis, the bone aligns with everything and rotates as I want it to, but when I move the Arm the gear does what it does in the picture.
I will update the post and attach a link to a file, though it is pretty much just about the 3 bones in the picture, as a proof of concept for me.
Well, an animation is going to be tricky, as the whole setup isnt working and I dont have a reference for the motion, just the idea. But I do have uploaded the .blend and hope the link works.
As for what I want to achieve, its an arm I want to pose and I want the gears that are part of the arm to move as I am posing, but the gear jumps out of alignment when I move the upper arm, ergo I amin need of another constraint that I cant get to work with the copy rotation constraint.
have you bee nable to download the .blend file?
The Cog bone (hehe) has a copy rotation constraint and rotates counter to the lower arm, but when you move the upper arm the cog moves out of alignment, even when the arm is completely straight.
I am going to add some extra mesh, have patience with me ^^
Setting it to Add and to work in Local Space I think gives you what you want.
TBH - I think I would have used a driver on this instead of a constraint. It appears to work for a full 360 degree rotation, which is more than an arm can rotate, so it’s probably fine. Used to be, in older versions of blender, drivers were the favored method for rotating gears. Probably just a habit of mine to use driver instead of constraint.
Thank you, I knew the answer was simple.
I havent been looking into drivers so far, but the rigg was supposed to make the animation automatic, as there are about 10 cogs that move independently. Many thanks
PS - I forgot to mention this. In your original file, the Cog bone changed it’s rotation drastically because of the constraint. To see this, tab in and out of edit mode. That type of behavior is a clear sign that something isn’t right. Switching from pose mode to edit mode, constrained bones might change in Loc/Rot/Scale a small amount. Anything more than that, you have a problem.
