I am having some unexpected results with the curve modifier for a curve in the y-z plane.
I have a blend file attached and two screen captures.
In the first image, I have the object I want to modify and the curve modified selected. I want the curve to bend the left and right sides of the object down. The not_visible.png shows the object with the modifier not visible. The modifier does bend the object along the curve but also appears to rotate the object along the 7 axis by 90 degree. The visible.png shows what the modifier appears to be doing. In the blend file the object is tread_03 and the curve is NurbCurve_large_radius.
I also have a curve named NurbsCurve which is in the x-z plane and it modifies the object along the x axis as I would expect.
I have tried rotating the curve and then applying the rotation. I have tried avoiding the curve rotation and simply move the control points in 3d in edit mode. I’ve looked at the curve tilt but don’t really know if I can make a change that would apply. I looked at local vs global coordinates but I’m assuming that applying rotation would align the two and the experiment of not rotating the curve would mean the local coordinates wouldn’t have changed. I searched articles and the posts on the message boards but am still unable to figure out what’s happening.
Does anyone know why the curve is apparently rotating my object as the curve modifier is being applied?
tread_sample.blend (513 KB)