Hello
I just bought my first blank to build, and I have an old rod building book that told me to find the spine of the blank and mark it.
I did as the book showed and slowly rolled the blank in my hand while one end was on the floor.

My question does the "spine" bend in two directions or just one.

Second once I find the "Spine" for a casting rod the guides should go on the opposite of the bend correct?

the spine, or bend shows me the way the rod would bend when fishing so, I deduced that, am I correct?

I picked up an old fly rod that only has the tip top guide on. I rolled it and found the tip top was turned 180 out from the bend or "spine"

Lots of blanks will seem to have two spots where they 'kick' Try to find the stronger one.

You can put your guides on either side of the kick. Lots of words have been written about which side to use and why. I don't think it makes too much difference. I've used both, and haven't noticed any effect at all.

Some major rod manufacturers, including Sage, don't even spine their. They look for the cosmetic curve to the blank, and put the guides along the curve. This may or may not be the same as the spine of the rod. Try going to a rod store and spining the tips of various rods. It's pretty amusing.

Some blanks do seem to have two spines. I have noticed that one of the two is deffinetly stonger than the other.
When I tie a casting blank I use the stonger of the two and will tie my guides on the opposite side of the bend. I preffer a "faster" feelling rod for most of my fishing and my experience is that this takes full advantage of the "backbone" that a particullar blank has to offer.

just my two cents