My Bernina 440QE uses a separate motor to wind a bobbin, so you can actually wind a bobbin while you are sewing or embroidering, but from a second spool or cone of thread, of course. I have never tried to wind a bobbin using the same thread that is going through the needle - not sure I would want to. Usually I wind bobbins from a different spool than the one I'm using for the top thread anyway. But the machine is so easy to thread - and the needle threader works so well - I don't feel a need to avoid re-threading.