Node hammerNode = PhysicsTestHelper.createPhysicsTestNode(assetManager, new SphereCollisionShape(.3f), 1);
hammerNode.getControl(RigidBodyControl.class).setPhysicsLocation(new Vector3f(0f, -1, 0f));
rootNode.attachChild(hammerNode);
getPhysicsSpace().add(hammerNode);
joint = new HingeJoint(holderNode.getControl(RigidBodyControl.class), hammerNode.getControl(RigidBodyControl.class), Vector3f.ZERO, new Vector3f(0f, -1, 0f), Vector3f.UNIT_Z, Vector3f.UNIT_Z);
getPhysicsSpace().add(joint);
}