three.js rotate Object3d around Y axis at it center

This answer helped me, but the code isn't quite correct. The axis has to be a unit vector, and object.rotateOnAxis() is incremental.

Here is a working example:

var axis = new THREE.Vector3(4, 0, 7).normalize();
var speed = 0.01;

// set up scene, etc.

function animate () {

    // other code

    if (object) {
        object.rotateOnAxis(axis, speed);
    }
}

Have a look at Object3D's rotateOnAxis(axis, angle) function. It should be something like:

//declared once at the top of your code
var axis = new THREE.Vector3(0.5,0.5,0);//tilted a bit on x and y - feel free to plug your different axis here
//in your update/draw function
rad += radIncrement;
object.rotateOnAxis(axis,rad);

HTH