Sewing long edges
I'm working on a quilt for my grandson and want the last border to be mitered. I'm sewing strips together, 1 1/2 inch, 2 1/2 inch, 1 1/2 inch, 2 1/2 inch, 1 1/2 inch, 3 1/2 inch. I want the corners to be mitered.
I did fine sewing the 3 1/2 inch, 1 1/2 inch, 2 1/2 inch. The strips stayed straight when pressed. When I sewed the next 1 1/2 inch strip on the whole piece bowed. I used my walking foot so the bottom moved at the same time. I did sew them all the same direction. When I take the last two pieces off and sew one of them back on I can keep the strip straight.
Did the piece curve because of the difference in width of the strips? Do I need to cut the strips the same length before piecing? Any suggestions how to solve this problem?