I was wondering if anyone could help me out with figuring out how to use Shape Key Drivers for the model that I've been working on for quite a while.

Basically, I need my model's head to be able to tilt upwards, going from this...

enter image description here

...to this...

enter image description here

...without any problematic mesh deformations, like in the picture below, or the head losing it's general shape, which has been quite a bit of problem for me while trying to setup the head.

enter image description here

The only option I've found thus far in getting the head to bend in the way that I want it to has been to use Shape Keys to iron out the deformation problem near the neck. The problem now, however, is that I still need to somehow get the Shape Key to work when the "muzzle" bone is rotated upwards. I've been trying to apply a Shape Key Driver to see if that would work, but unfortunately, I can't seem get the driver to work properly and looking up tutorials on Shape Key Drivers hasn't exactly provided much help either.

I greatly need help in how to properly setup a Shape Key Driver, and any help on this matter would be greatly appreciated.


After failing to properly implement the Shape Key Driver, I've noticed that I am no longer able to manipulate the Shape Key Value. Every time I try to move the slider I get an error message at the top of the screen reading "Can't edit driven number value, see graph editor for the driver setup". I'm not sure what the error message is referring to or whether or not it helps in identifying why I'm unable to implement the Shape Key Driver but I thought it would worth mentioning anyway.

Also, I'd appreciate it if people would stay focused on the subject of how to implement Shape Key Drivers. I'm well aware that the way the armature for the head is set up is unconventional to say the least, but unless there is something seriously wrong that would cause a major problem with setting up the Drivers, I would much prefer to keep the focus on the main subject at hand.

  • 1
    $\begingroup$ Are you sure about your rigging (what is the purpose of the head if the muzzle does everything?), about your rest pose (why does your head lean forward?) and about your mesh topology (why did you apply the modifier?)? Maybe you should rethink all of these before shapekeys and drivers, I guess they are last ressort... $\endgroup$
    – moonboots
    Aug 22, 2018 at 10:20
  • $\begingroup$ The reason that I have the head setup the way that is currently is because it was only way I could find that worked for my model. Every other method I tried so far would result in grotesque distortions that caused the head to lose its shape as it tilted upward. The current setup maintains the basic shape of the head with the only problem being the way that the geometry at the back of the neck is squashed, which is why I need to use a Shape Key to straighten out the problematic geometry. $\endgroup$ Aug 23, 2018 at 6:29
  • $\begingroup$ As for why for the head looks the way it does in it's resting pose, that's just simply how the character I'm making looks. The Moomins from the classic children's series of the same name is the closest parallel that l can think of to character I'm making is supposed to look like. As far as I can tell, no matter what I do, I'm going have to a Shape Key at some point. Even if I were to radically alter the topology, I just don't think that there's anyway of getting the model to look the way I want to without the use of a Shape Key, so I figure I may as well learn how to use them. $\endgroup$ Aug 23, 2018 at 6:50
  • $\begingroup$ The Subdivision Division Modifier was applied by mistake, but I don't think it matters because this model isn't the final version I intend to port into Unreal Engine, I've just been using it as a test bed for figuring out how to get the head to move up and down without any problematic deformations before I make any serious alterations to the final model. $\endgroup$ Aug 23, 2018 at 6:57
  • $\begingroup$ The issues you're having are all due to weights and bone placement, and you're getting ahead of yourself by running to corrective shapekeys this early. Even so, I'd tell you what your drivers are doing wrong, but there aren't any drivers in the file you provided, so I can't. $\endgroup$
    – Nathan
    May 16, 2021 at 1:17

1 Answer 1


You need to know, that weight are not describe how bone influence on mesh. Instead, weight describes how the effect on the mesh is distributed between the bones. So if you have setup only one bone, 100% affects is from this bone even if you set 0.0001 weight.

Also, you can get nicer and smother results if you set armature modifier before subsurf.

  • $\begingroup$ I already know about positioning the Armature modifier above the Subdivision Modifier, I just forgot to make that change on this particular version of this model. As for the rest, I don't really have a good reading comprehension of technical issues but does that affect the way that the Shape Key is suppose to work in conjunction with the muzzle bone? I mean the bone is suppose to manipulate the Shape Key, so that it can allow for the transition from the default pose to the head tilting upwards with the alterations to the mesh area around the neck. $\endgroup$ Aug 22, 2018 at 7:42

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