I used a bobbin winding machine for my embroidery machine. Yes - the embroidery machine will wind bobbins, but when you do machine embroidery you use a lot of bobbins and it felt like I was always having to wind bobbins. I now just use the prewound bobbins for machine embroidery, and sometimes for piecing, too. They hold a lot more thread than regular bobbins so they are a timesaver.