Quite often when using flannel for raggy quilts we use a 1/2" seam, (12" blocks with 11" batting squares, X across the squares of top, batting back) join squares w/ 1/2" seams then clip, clip, clip ( the closer the better for good full * chenille like,* ragging) you clip down to almost the seam line, being careful to not clip the seam. ( minky doesn't work well, it does not fray/ rag just gets stringy.... Cottons, cotton flannel, and homespun s work great for raggy quilts. After finishing construction and clipping give it a good shake outside before washing, then again between the washer & dryer. When you put it in the dryer check every 10-15 minutes to empty the lint trap, it will fill up fast & often. I usually take it out & shake it 2 or 3 times while drying too.