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I appended a rigged model from sketchfab. The rigging works great, however the object is too small for the scene and I need to scale it up by quite a bit. However, when I scale the armature the bones rotate and do not keep their original orientation/position (see image, left is before scaling, right is after scaling up).

There is no animation for this object, as of yet.

What is causing the armature to not scale regularly?

original scale on left, increased scale on right

EDIT: I've tried scaling all of the bones at once in both Object mode and Pose mode.

Here is my blend file (blendfile)

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  • $\begingroup$ Did you scale the bones individually? If so, in Object mode select the whole armature and try to scale it. Let's see what happens then $\endgroup$
    – Tsybe
    Feb 20, 2022 at 16:45
  • $\begingroup$ really hard to say without the blend file. So providing your blend file would help... $\endgroup$
    – Chris
    Feb 20, 2022 at 17:34
  • $\begingroup$ I've edited the post to include an example blend file $\endgroup$
    – JMade
    Feb 20, 2022 at 18:06

1 Answer 1

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When armatures don't do what's expected, it's usually because of constraints or drivers. Here, there are no drivers-- it's constraints. If we enable the display of all bones, we can see that this armature has a few constrained bones (colored green or yellow). If we inspect the bone constraints on these bones, we can see that one bone has a pair of limit distance constraints that operate in world space. Scaling our model isn't going to change world distance units, so those limit distance constraints aren't going to work right on a scaled-up model. We can change those to act in pose space instead, after which, the distance will be measured in units appropriate to the armature scale, and the main problem will disappear:

enter image description here

That's the most noticeable problem, but there's another one. Our springs are curve objects, which use hook modifiers to be affected by the armature. They are not parented to anything, so as we scale up, the springs will appear thinner and thinner. These are safe to parent to the armature-- their hooks will still work the same way-- at which point they'll scale up with the armature scale. So reset scale on armature, then parent the springs to the armature with keep transform. Now, they'll scale up with the armature. Here it is after parenting one spring then scaling the armature (and transforming a few bones, to make sure it didn't break anything):

enter image description here

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    $\begingroup$ Thank you for this thoughtful answer, Nathan! How do I enable the display of all bones? I tried unhiding them, and looking in the bone properties to see if they were hidden there but no luck. $\endgroup$
    – JMade
    Feb 21, 2022 at 11:45
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    $\begingroup$ You need to enable the display of all bone layers, in properties/object data/skeleton. $\endgroup$
    – Nathan
    Feb 21, 2022 at 15:52

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