Sorry, only just realised that not all my message appeared. I was trying to say that if you don't have a machine that tells you it is going to run out on the bobbin, if you put full bobbins on the top and in the bobbin case, when the top bobbin is getting low on thread, then so with the bottom bobbin. It just means you have to wind extra bobbins all the time, but that isn't too time consuming.