This explanation of the rod blank 'Spining Concept' will help you find the proper side of the rod to place your rod guides when building your custom rod.

Spining the blank; this simple process has caused much confusion and debate within the rod building community. Understanding why there is such a thing in the first place may help eliminate a lot of the confusion. The act of 'spining' is finding the differences in the wall thickness of the rod blank after the flat graphite (carbon fiber) cloth is wrapped around a tapered steel mandrel and then oven cured. The tapered mandrel has the rod designer's line and length taper specifications center-ground to within thousands of an inch. The designer dictates the amount of graphite cloth (typically combined with a resin scrim) that the finished rod blank will have and how much overlap there will be. The graphite material is cut into a tapered pattern, which will be wider at the butt end and narrower at the tip end. Because of these 'ends', each blank will have end spots, which will feel like 'high points'. These high points, which typically run the entire length of the blank, are what we call a 'spine' or 'spines'. Just like the spine in your body, it is stiff area in your back but different in rod blanks in that you may encounter several spines depending on how the graphite cloth is applied, or 'laid-up' on the mandrel. We usually will have just two spines to deal with, the beginning edge of the cloth and the ending edge of the graphite.

When the graphite is wrapped with the heat shrink tape and oven cured, a 'natural curve' will appear along the rod shaft. This natural curve will be apparent when you sight along the axis of your blank and it has a definitive curve to it, if not, you're lucky and accidentally got a straight one. There are two things that the custom rod builder must accept as fact; first, no rod blank is perfectly straight and second, no rod blank is perfectly round. The curve of the blank will be more visible when you rotate the blank shaft when sighting down the length of it. This natural curve is also called the 'weak side', where the thickness of the graphite material is less than the other side, or the strong side.

So far we have a weak side and a strong side as determined by the amount of graphite material wrapped around the steel mandrel. You can check this weak side by holding the blank at a 45 degree angle with your one hand near the tip and then by pressing down and rotating at the same time with fingers from your other hand. The resistances you feel on both sides are the high points or spines. You can also set the blank section butt on the floor and press down on the tip with your finger. The blank will flex or bend showing you the concave and convex sides of the blank. The concave side is the weak side or the 'guide side' (this is what happens when you flex the rod during the cast). This works mostly with the thinner tip sections whereas you will have to do the sighting and 45 degree flexing for the butt sections. Remember the opposite side of the weak side is the thicker part of the blank and will result in more power for lifting and fighting big fish as the graphite resists compression as a result of more material in that side.

For the average trout rod we put the guides on the weak side or the natural curve side. This will prevent the rod from twisting in your hand. If the guides were put off to the side, this would cause the rod to twist during the cast resulting in inaccuracy, this is why the rod guides are typically put '90 degrees to the spine' as one manufacturer states but this will result in the same thing as putting your guides on the weak side. Finding the curve also insures a better fit for all of your sections, whether you have a 2 piece, 4 piece or six piece. Because the sections are all made the same way there will be a 'fittiong factor' to deal with also. Since all the sections are 'out-of-round' you have to make sure all the curves line up correctly along the rod length. If you have ever had a rod section fly off during fishing or casting, it may be due to the fact that the rod sections were not properly spined and aligned.

Maintaining casting accuracy in trout fishing is more important than lifting power as in big game fishing. By properly placing your guide, your rod will track properly through the casting plane. Whether you decide to place your guides on the weak side or the strong side is a matter of individual decision but the awareness of a spine or spines and what they are will give you a better understanding of rod design and will help you create a finely tuned fishing rod.