You will definitely need to move your needle over a couple of threads or guide the fabric to be a "scant" 1/4". Even though we measure our sewn line and it says 1/4", you need to take in account the size of your thread. I have this issue as well. Cotton thread - which I use- takes up space and when you multiply this times four seams, you loos that little 1/16. So take it over a couple more threads. i would take one row out is all and sew it a scant extra out and see how one block responds. If it does well, would repeat x 4. Otherwise you will have to do the stretch to get to the 1/2" mark and it may distort the whole quilt. Just a suggestion. I learned this because I love to to minatures and Sally Collins stresses this when you are sewing minatures. You will see a difference in all your work.