# How to use IK spine with correct tilt rotation from the curve?

So I'm trying to make a rig for a minigun's ammunitions destined to be export to game engines.

I want to make a rig with both ends of the ammos parented to the gun and have a few bones hooked to a curve in beetween to animate physics. After a fiew researches, I found the IK spine constraint to be similar to my needs, but it doesn't support the tilt information from the curve.

There's a workaround found on deviantArt I tried to recreate (Here's the post), basically it says to use a plane mesh with as much subdivisions as there are bones in the IK spine, add a curve modifier on it so the mesh deforms accordingly, and add each vertices of the plane to a separate vertex group so our bones can use a locked track constraint and follow the rotation of the vertices.

In theory it works, but in practice it does something weird, the rotation of the plane do have some effect on the rig but it seems the rotation of the mesh don't have an absolute influence on the rig where it should, and the location of the vertices influence the rig rotation even tho it shouldn't??

The rotation works as intended

The location works too but have some effect on the rotation where it shouldn't (notice how the plane isn't tilted)

And with a combination of the two, the rotation has little to no effect, even tho the plane is extremely tilted

to summarize how it all works:

1. Curve points hooked to control bones
2. Drivers to control curve points tilt from control bones x axis
3. Curve Modifier on a guide mesh to get tilt info from the curve at any given point
4. Vertex group for each vertice in the guide mesh
5. each DEF bone has an IK spine constraint to stuck to the curve and a locked track constraint targeting corresponding vertex group

Am I doing something wrong? Is there another way to do this?

I beg for blender masters wiseness as I spent days on this problem :,)

Here is the issue in an isolated file: