I would imagine it winds bobbins as tight and nice as the pre wound ones. No sewing machine can wind a bobbin as perfectly as a professional bobbin machine. I have two gross of pre wound bobbins so I don't need any more bobbins for a while. And I have a shoe box full of bobbins my DGD wound for me using the Sidewinder. She loved to wind bobbins when she was younger. I kept Walmart sold out of bobbins when she came over. LOL