Originally Posted by
PaperPrincess
Wind two bobbins. Put one on the top and the other in the bobbin. The machine should use thread from top and bottom at about the same rate. You can keep an eye on the one on the top. This is only going to work if you use the same thread in the top & bobbin!
Have you actually done this? Asking because I think the top thread is actually used at a faster rate than the bobbin thread. I think the top thread would run out long before the bobbin did. This is based on my observations when unsewing and keeping both thread tails intact to knot and bury (when machine quilting). The top thread tail is always long enough to work with long before the bobbin thread is.