How can I get automatic weight painting to pick up every object intended?

Question

I have a collection of objects for which I want to set up a rig. There are 33 segments in this chain, and I have created, extruded, and renamed bones for each segment. All bones are positioned precisely in each segment object. I selected all 33 segments, then selected the extruded bones, and parented the objects to the bones using automatic weights:

After doing this, I see that when I enter Pose mode and move any segment, the last bone in the chain (#33) moves with it, but the object which should be parented to that last bone doesn't:

How can I correct this? It seems apparent that Segment 33 isn't parenting to bone 33 when the other are parented to their corresponding bones, but I don't know why or how to fix it.

Answer 1

If you didn't forget to select that segment when using automatic weights, then it should at least have all the vertex groups needed for the bones' assignment. Since it's a simple object, we can just assign all its geometry to a singe bone's vertex group in edit mode, that will be quicker than painting weights:

1. Select Segment 33 in Object Mode
2. Switch to Edit Mode with ↹ Tab
3. Select all the geometry with A
4. Go in Properties Editor > Object Data tab > Vertex Groups panel
5. Click the ˅ button and run the operator Remove From All Groups so that we are sure this object isn't influenced by any other bone.
6. Select the vertex group with the name of the bone you want to assign this object to, and click the Assign button.