I have been doing tube quilting and having trouble getting my triangles to turn out to the size they should. I've watch the tutorial on you tube. My triangles end up being 5 3/4 inch instead of 5 1/2. I have cut the strips to 2 1/2 inch and my seams are correct. Have I done something wrong or is it a case that a 4 1/2 inch strip does not give a 5 1/2 inch triangle? Any help would be appreciated. :( :(