Why does my mesh kink when I bend my bones

Question

I'm new to blender and trying to make a corner joint that I can set the angle of in Unity. Ideally if I set an angle like 45 or 90 degrees the bend would look uniform like this:

So I set up a rectangle in blender and gave it some bones. And I can move them in pose mode and even in Unity when I import it.

If I bend it too far though, the mesh kinks like this. The inside bend looks more like I tried to crush a can than a smooth bend. I tried adding new bones but had the same problem.

And for some reason the end bones don't deform the mesh when I move them. Almost like they aren't attached or something.

This is how it's setup:

So how do I make my mesh deform nice and smoothly like I'm bending a pipe?

Answer 1

So how do I make my mesh deform nice and smoothly like I'm bending a pipe?

By spreading your rotation out over more bones:

A bone can only ever represent a single rotation, not a continuous set of rotations, and vertices interpolate linearly from the orientation given by one bone to the next. To make smoother deformations, sometimes we just need to use more deform bones. (We also sometimes just need more vertices. I wouldn't add more bones than the most shown here without adding additional vertices to my mesh.)

I don't know if Unity supports "quaternion skinning", but if it does, you can try enabling volume preservation, which will improve this kind of deformation at shallow angles, although at the risk of making it worse at sharper angles: