Re: Easiest way to find the spine?
I am betting Auntie Em is referring to building on the straightest axis. Sight down a section to see the straightest axis. Once you find it add another blank section and sight down. Keeping adding your blank sections by lining up the straightest axis until the blank is assembled. I may be way off, but that is what I read into the post.
I do what Rip Tide does only I have never used the toe of my shoe. I usually keep the end on a hard surface. Going to give the shoe toe a try.
Not every section, especially butt sections, will have a distinguished spine. Or better yet, sometimes you might find two apparent spines on a section.