I have the book with DVD called Serge and Merge Quilts. Ido use my serger to piece large simple blocks. The last one I did was a quilt for my son to hug him. I used a contrasting thread with the flatlock stitch to join pieces together. After it was pieced and sandwiched I stitched inthe ditch down the center of the flatlock with another contrasting thread. I didnt find that it added too much bulk for quilting.