Somewhere on the internet there is a tutorial that shows marking a straight line 1/4 across the what will become the bottom of your tube, and stopping at that line when marking your diagonals for cutting. I used that the first time I ever made binding this way, and it worked perfectly. Of course, I apparently forgot to book mark the site and now can't find it again for a more thorough explanation. But, when I last made the continuous binding it was off until I remembered this and marked my fabric tube accordingly. Hope this makes sense