Weld Orientation Axis Fusing?

Help and Feedback Scripting Support
#1

I’m using Lerp() to animate a part that’s welded to the character’s torso.

When setting the orientation of C0 or C1, the X and Z axis seem to combine together.

I’ve looked through the developer hub, but haven’t found much. Someone proposed rotating the object using C1 instead of C0, which worked until I needed to set an orientation all three axis.
I’ve also tried different rotation orders, it didn’t make a difference.

This is a reoccuring issue that’s been bugging me for years. Orientation seems to work normally on some objects, yet does this on others.

Media:

Resulting orientation
image

Code:

local function onRenderStepped(deltaTime: number): nil
	sine += deltaTime * speed

	Weld.C0 = Weld.C0:Lerp(new(4.25, 2.5 + 0.25 * sin(sine), 1.75), 0.1)
	Weld.C1 = Weld.C1:Lerp(Angles(rad(90 + 10 * cos(sine)), rad(90), rad(-5)), 0.1)

	return
end

Any help much appreciated!