Fortyniner, I am confused by your mention of sizes.
As far as I can figure out, 3 strips of 2-1/4" fabric sewn together with scant 1/4" seam should measure a total of 5-3/4" after sewing two seams.
A more common method is to cut 3 strips 2.5" wide and aim for a measurement of 6.5" exactly after sewing two seams (not 6" because there is an unsewn seam to left and right that add up to .5").
Edit: Regarding your question, you want to *sew* a scant 1/4" seam so that after pressing, the fabric taken up by the seam (including turn-of-cloth) is *exactly* 1/4". If you think about it, we all draw block patterns based on exact *finished* 1/4" seams. In order to achieve the exact finish, we need to sew a "scant" seam to allow for turn-of-cloth and space taken up by the sewing thread.
Last edited by Prism99; 03-17-2013 at 10:28 AM.