Multi-legged robot rigging problem

I took an available model of a robot arm and turned it upside down to make a leg with a wheel instead of a foot. I have it rigged and it seems to be working. I even have a driver working to spin the wheel when the main bone moves in x.
I want to make a robot with 4 of these legs, so I selected all parts of the leg, including the armature. I duplicated it 4 times and moved each into position at offsets of xy +/- 0.125 (near the corners of the cube)
Finally, I wanted to join all the armatures into one, so I selected all 4 and hit ctrl-J. They joined, but most of my robot parts flew off the screen.

Am I missing something? I’ve attached the blend if anyone wants to take a look.


stair_climber3.blend (1.66 MB)

You have an object “Cube.002” that is kilometers away from the origin. When you select all, that is included and Blender gets confused trying to move a selection that spans such a great distance.

Even if you don’t duplicate the leg… if you just select all and try to move, it will go crazy too.

I got rid of the cube.002 but when I duplicate the legs and join the armatures parts of the mess still move around. It’s strange, some times the duplicates move, some times the originals move. I don’t know what I’m doing differently. I’ve tried to apply loc/scale/rot to each mesh, but that doesn’t fix it.

I finally figured it out. When you duplicate the armature, only the armature name is changed. The names of the bones inside remain the same. So when you join the two, the mesh is apparently linked by name and it randomly jumps to one of the two with matching names.
If I change the names to be unique before I do the join, it works as expected.

Right on. I was just getting ready to post that.

Glad you were able to figure it out.