Sometimes you may want to freely rotate a part in an assembly without having to use the Triad tool. To do this:
1) Be in an assembly workspace
2) Hold down SHIFT
3) Click and hold the LMB down over your part
4) Drag the mouse around. The part rotates freely with your mouse.
If your part is fully unconstrained, it will rotate in a truly free manner. If it has constraints on it, it will behave in adherence with the constraints. If it appears to be behaving in an unexpected manner while constrained, try rotating the view a bit and rotating from a different angle.
1) Be in an assembly workspace
2) Hold down SHIFT
3) Click and hold the LMB down over your part
4) Drag the mouse around. The part rotates freely with your mouse.
If your part is fully unconstrained, it will rotate in a truly free manner. If it has constraints on it, it will behave in adherence with the constraints. If it appears to be behaving in an unexpected manner while constrained, try rotating the view a bit and rotating from a different angle.