I think the scant 1/4" all stemmed from the featherweight - singer 221. It does make a scant quarter inch seam and has been the only time my pieced top turned out the size the pattern said! (Aurifil thread works great to - does not take up any bulk in the seam allowance) Good to hear all of this discussion though as I'm starting a business venture to make pre-cut quilt kits.