I have an old Pfaff and didn't have to rethread to wind a bobbin. However, the bobbin winder part quit working recently and I bought a sidewinder rather than have to do without my machine for weeks for the repair. I really like the sidewinder, I can wind many bobbins very fast. My bobbins don't really fit WELL on the thing, I have to force them on there pretty hard. Getting them off is harder. I figure eventually it will wear in. Or I will break the thing, one or the other.