Fly Rod Manufacturing
How is my fly rod manufactured?
If you want to get a headache in a hurry, just start researching how fly rods are manufactured. So many terms — scrim, prepreg, resin, modulus of elasticity, high modulus graphite. Not to mention all the special PR spin each fly rod manufacturer puts on their materials. (Graphite II, Graphite III, Graphite IV, IM6, GL3, GL4, High Matrix, Sage fly rods new G5 technology with modulus positioning system (MPS) or St. Croix’s IPC technology to produce rods with one continuous taper. Let’s start with a Glossary of Terms.
Glossary of Fly Rod Terms
- Carbon fiber or Graphite — fibers of carbon processed in one roll with the fibers aligned along the length of the roll. The fibers then are coated with a bonding resin.
- Scrim — The addition of a small amount of fiberglass to the graphite matte. Or by spiral wrapping additional graphite fibers around the rod blank. The last method yields blanks of 94 to 96 per cent graphite and is the more versatile of the two methods.
- Resin — is a type of plastic like adhesive that is added to the blank to strengthen the matte and scrim. The resin is harden by curing in a baking oven. Different resins will give different rod characteristics.
- Pre-preg — the combination of the carbon matte, scrim and resin is called a pre-preg. The pre-preg is then cured in an oven at a set temperature and time. After that, it is ready for cutting a pattern called a "flag"
- Flag — the rod blank pattern cut from the pre-preg. The flag is now ready to be rolled around a mandrel to form the actual rod blank.
- Mandrel — A precisely tapered metal rod used to define the shape of the rod blank. Different mandrel shapes help to determine rods of different actions and tapers. Quality rods are designed on a mandrel for each piece.
The flag or pattern is rolled around the mandrel using pressure or shrink tape. If shrink tape is used, the rod blank will have spiral marks that must be sanded or ground smooth.
The mandrel and wrapped flag is cured in a baking oven at a precise temperature and for a precise time. Then the cured flag is removed from the mandrel. Better blanks have a smoother finish right off the mandrel. Shrink tape wrapped blanks will have small ridges left when cured. These ridges must be ground down to a smooth finish. A matte finish blank is left unvarnished or finished with a matte or satin varnish.
- Modulus of Elasticity — is a fancy term for the amount of stiffness in a rod blank. (It actually stands for Young’s Modulus of Elasticity from Physics.). As typically used, Modulus refers to the stiffness of the dry graphite fibers — before mixed with the resin to become the prepreg.
- Spine — All rod blanks have a "spine" from the manufacturing process. The spine means the blank will favor flexing along a particular plane. Each rod section may not have the same spine so fitting rod guides is finding the "Effective Spine" Best quality rods today may have little or no spine.
Finding the spine. Take each rod section and set the butt section on a table or non-slip surface. Put slight pressure on the rod about in the middle of the section with the finger tips and then roll the rod blank gently in one direction. You will feel a point where the blank "snaps" over a point of stiffness. That is the spine. Sight along the blank and see if if the guides are aligned along the spine.
Do this with each rod section for the rod you are looking at. With the rod assembled, you should be able to tell the spine by the same test. Do this gently unless you want to buy a broken rod.
Why the Spine is important! Under load, the rod will always turn itself so the load is resisted by the spine, the rod’s line of greatest strength. The guides must be aligned along this line of resistance. Failing this, the rod will turn under load to the spine regardless of where the guides are set. You don’t want to be fighting a big fish and have the rod twist under load.
Blank and Rod Properties
- Tapers — Rod tapers come in several flavors.
- Compound or progressive where the blank makes several changes to the taper over the length of the total blank.
- Continuous or smooth where the blank is one smooth taper from butt to tip. (These types of tapers are a newer taper allowed by better ferrule design.)
- Ferrules — The connection points between sections of a rod. The ferrules generally offer a point of increased resistance in the blank which will affect the overall action of the rod. A badly designed ferrule can break a blank from the leverage force applied to the inside of the blank. This applies to two piece and multi-piece rods. Newer ferrules are often thinner walled than older designed ferrules. And so offer a better rod action.
- Tip over Butt — are ferrules where the butt of the section above tapers enough to allow the male end below to be fit into the female ferrule section above. (These were the first effective fiber glass design ferrule to replace metal ferrules.) They are still in common use today. The female section of the ferrule is usually reinforced with a section of cross-wise graphite fibers for lateral strength under load. Each blank section with this type of ferrule must be made on a separate mandrel.
- Internal or Spigot Ferrule — A spigot is glued into the butt section. The spigot is a perfect fit for the ferrule section above. To reinforce the female ferrule section above, graphite is glued perpendicular to the graphite blank. Many rod manufacturers who use this type of ferrule, maintain it provides a consistent transfer of energy and adds very little weight to the blank. There is usually a slight gap in each ferrule when the rod is assembled to allow for wear. (note: I have one 9 ft graphite rod with this type of ferrule system. I much prefer the tip over butt system.)
- Sleeve Ferrule — an external female sleeve is glued over the butt of each rod section. Then the male end is fit into the the female sleeve to assemble the rod. There is a continuous taper inside the ferrule which is an extremely strong design. But some rod designers feel this type adds too much weight and stiffness.
Scott Fly Rods have engineered a sleeve over ferrule to produce a thin walled extremely strong smooth ferrule. Scott claims their ferrule system allows for a smooth transfer of power through out the rod blank.
- Flared Ferrule — Designed and patented by Gary Loomis. This ferrule is based on the tip over butt system. The rod section has a flare at the female end of the ferrule. The butt section is inserted into the female end. This type of ferrule produces a small tip over butt ferrule with excellent energy transfer through the short ferrule length. (Editor Note: I have a G.Loomis rod which I very much enjoy using.)
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