Rigging tank treads


Seems like bones and vertex weights are causing some issues for quite a few people, and I am no exception.
I am trying to rig five bones to represent the individual road wheels, plus two further bones to represent the static wheels at either end. I have these linked to my track mesh and assigned vertex groups to each one. I just cannot seem to get gradual mesh deformation, it’s either 100% or nothing. I have attached my blend file if you want to take a look and perhaps make it work.

Here are some screen to help illustrate the issue.

This shows one of the vertex groups, with 1 weight assigned to these vertices.

These vertices, in the same vertex group, have 0.5 assigned to them.

When I pose the middle bone, it just moves the first four vertices fully and ignores those in the second shot.
I have read about weighting only working across multiple bones, but despite trying to assign this kind of weighting to all the bones, I still get an ‘all or nothing’ result and not the gradual deformation that I am looking for.

Can some shed some light, or maybe tweak the attached blend file to illustrate how it should be done?

Thanks in advance.



No one has any advice on this? Here’s another image to illustrate issue further.

I would expect the centre section to be affected fully, then the outer vertex group less so, but you can see it is affecting both vertex groups equally despite their weights being different. Surely this can’t be that hard?


Its deforming like you show because the vertex only has 1 weight. If a vertex weight has a value of 0.1 but no other influences it will “normalize” to 1.0. The same happens if a vertex has two weights of 1.0 it will be “Normalized” to 0.5.

Every vertex on your mesh must have a vertex wight that adds up to 1.0, any vertex that has zero weights influencing it will not deform.

Thanks for the reply, but applying that logic doesn’t seem to work. I have simplified the .blend file and now only have three bones.
You can see from the screenshot that the middle bone has a central area of 1 weight, then outer region of 0.5. The right bone is the same and shares vertices at 0.5 weight with the middle bone. I still get all or nothing influence - I would expect to see the deformation shown by the yellow line.

New .blend:

Any ideas?

The three bones in the simplified blend file are all from different armatures. I combined the three bones into a single armature. This was the result:

It actually does work when the bones are in separate armatures, you just don’t see it unless you move both bones. My recommendation: always just use one armature, don’t create a new armature object for each individual bone. Shift+A (add) -> Armature -> Single Bone, then TAB into edit mode and Shift+A add more bones from there.

Use 1 armature object with several bones instead of several armature objects with only 1 single bone. Your mesh object should only have 1 armature modifier on it, naming the 1 single armature object with several bones.

Do this with your file to see what I mean: Select the left bone, in object mode, shift select the right bone, in object mode, shift select the middle bone, in object mode. Now do a ctrl-J to join the three armatures into 1 armature object. Now select the armature and in pose mode, select the middle bone and move it.


Edit: haha… too slow, @xabotage beat me to it… :rolleyes:

Thanks xabotage and Randy… I applied your solution and it works a treat, one armature, several bones within. All the videos and posts about rigging have been based on an IK type armature which has a hierarchy of bones. Since my bones are not connected I didn’t know you could add more bones inside an armature without them being connected.

Finally I can make some progress!

I have some tutorial videos on how to do this… I use objects instead of bones but it’s not much different…

take a look here…



I posted some new Videos here on Rigging Tank Treads bringing my total of videos on this subject up to 11…

check them here…


and my two latest tutorial video’s here…