On tip I learned in a class how to have straight seams at the end of a seam is to put your left index finger on the left side of the foot as you reach the end of the seam. Works every time. Classes with excellent quilt makers are so worth the time so take as many as you can. I have learned so many tips and solutions to my sewing problems in classes. If your machine has zig zag function the stitches will always be at a slant. Over 5 mm machine is not easy to get a 1/4 seam without a lot of fussiness.