Originally Posted by Watson

There is a 4" platform underneath that is attached to the rest of the long arm. (Look behind at the back and you'll see the whole machine is shaped like a big "C" and goes above and below the fabric). It all moves at the same time. The platform has a hole in it and the needle goes down into the hole and picks up the bobbin thread which is underneath. They use "M" bobbins, which take more thread than a regular bobbin...but never enough.

Watson