Back in the 1880,s, Sir Isaac Singer offered anyone, one million dollars if they could develop a lockstitch machine(needle and bobbin), also known as a 301 stitch, where the bobbin would be as large as the spool of thread. 130 years later, it still hasn't been done. The machine would have to be 10 times the size as it is now, virtually making it not feasable. If anyone would like to try and invent one, be sure to invest in a few bottles of headache pills, or a few bottles of Jack Daniels. Either one of these remedies will kill the pain that you will inflict upon yourself by trying. I know this, because as most sewing machine mechanics/expert's, have, at least on a few occasions, tried. Thought I had it once, but in reality.......wasn't even close! Steve