Fishing Rod Blank manufacture

Here at Harrisons we start the production process with a roll of flat carbon fibre tape, and turn it into fishing rod blanks. Its a process I still find miraculous, the conversion of a flexible, almost "floppy" raw material into a stiff light precision instrument. There is nothing more rewarding than making things of quality, and here we describe how we do it. (Though we will not be giving all the secrets away!)

We buy in carbon fibre in a flat form called prepreg. That is short for pre-impregnated. Simply, the carbon fibre arrives as a wide tape, on a roll with fibres and resin mixed in metered quantities. This is a very different process to the wet lay up used in some industries. The benefits are accurately measured amounts of resin at all points in the composite and ease of handling. It's expensive stuff, a 50m roll can cost thousands of pound, and we consume kilometres of it each month. The resin, a modified epoxy system, does not cure at room temperature, but needs heat to make it solidify. This means the prepreg will not cure at room temeperature and it has an out life of months and can be refrigerated to keep for very long periods. Going back one step though, carbon fibre alone, is a black floss like material, very vulnerable to abrasion and damage. It is only the combination with a resin system into a composite, that makes it useful as an engineering material. So when we talk loosely about carbon fibre rods we normally mean carbon fibre and epoxy composite, but that is a bit of a mouthful!

Carbon is an interesting substance that has the ability to bond one atom to another in several different stable ways by virtue of it's covalent bonding properties. Diamond is made of carbon and is one of the hardest substances known to man. Carbon fibre has the carbon in long chains to produce excellent tensile properties. By the way, the Americans and much of Asia calls carbon fibre graphite. Graphite is actually a totally different form of carbon with flat sheet like molecules which have lubricating properties.

The prepreg suppliers may specialise in supplying small companies with off the shelf products, or run larger quantities of prepreg to the exact specification required by their bigger customers. Harrsion's are one of the bigger non aerospace users of prepreg in the UK. We have buying power that allows us to make great demands on the input quality of raw materials. We believe that material we currently buy is the best available. It is not the cheapest, but it is the flattest, most consistent, gap free prepreg available, and for that we pay a slight price premium. We also source some very light weight specialised prepregs from Japan. The prepregs can differ in fibre type, orientation and properties, resin content, and weight per square metre. At any one time we have about ten materials in use. We do not mkae a rod with one fibre from tip to butt, but use different prepregs throughout the rod, often combining three or four in one rod.

Carbon Fibres come in a variety of types, and brands. IM6 and IM8 were heavily promoted at one time, but other major products are, M55, M40, M40J, M46J, T300, HR40, a long list. These fibre types have varying properties when used in a composite. They vary in their modulus and strength. Modulus, is in effect "stretchiness". It is different to strength but can easily be confused. When you make a composite using high modulus fibres, you make a stiff tube or rod. When you make a high strength tube, it may bend more, but it will bend further before failing.

Fishing rods across a range of applications need high strength, high modulus and intermediate fibres to perform well. No one fibre is superior. High modulus though often more expensive, is less preferable than a cheaper fibre in some applications.

We tend to be a bit vague about where we use different fibres for two reasons. One, we believe we are ahead of the game, and we do not want to help our competitors. Two, its almost meaningless to the angler. What counts is performance.

Design is the first step. That is the most secret bit here, but one important ingredient is experience. There are a small handful of really knowledgeable quality blank makers in the world. We are one of them, and it was hard work getting there! So sorry, not too much information is public domain here. I can tell you we sometimes start a design with a blank sheet of paper, but more often we take an existing blank, and play around with it. Unlike those companies sourcing their rods from the far east, we have total control. We can go through a cycle of design to prototype in two hours. The importers tell you it took two years to develop a new rod. Most of that was probably spent waiting for samples. We can develop a rod here in hours. But then we test it for months.

A design has to be translated into a pattern. Like a dress design. Three dimensional tube, starts out as two dimensional pattern. The patterns are cut by hand from the prepreg. A rod section may be made from one simple wedge shaped pattern, or more often a complex lay up of irregular shapes and different materials. The subtleties of design make the difference. The little changes in taper, stiffening, the balance of materials. Particularly critical is the joint area where a Harrison blank will have a smoother transition than many cheaper rods.

The other variable besides materials, is the mandrel, the tapered rod around which the tube is formed. We have a large stock of mandrels of various tapers and size. These are made to our specification in America. We have a large number of each type, as it is uneconomic to make rods one at a time, we have to work in batches.

The mandrels are cleaned and prepared with a release agent, then the carbon prepreg pattern is rolled around it using a pneumatic rolling table. Its like rolling a giant tapered cigarette. It is not too clear in the image but blank maker Andy Mantova is preparing the prepreg on the right of the mandrel so it can be rolled by the movemnet of the tow pressurised and heated "plattens". The top platten descends and bottom platten produces the rolling motion.

After rolling the prepreg is wound under controlled tension with a high performance heat shrinkable tape. This binds the prepreg tight to the mandrel and controls the pressure during cure. The pressure is required to control resin flow, exclude air and make a high perform composite.

The wrapped part is then placed in curing oven for a period, during which the resin is activated, gels, and cures. Cure time is dependent on part size temperature and resin system, a controlled cycle is measured in hours rather than minutes.

Faster low temperature cure systems are emerging for boat building, but are yet to be proven in rods. Longer slower cure times are favoured by us to get maximum consolidation and stress free composites.

On finishing the cure cycle, the mandrel is extracted pneumatically, the part unwrapped and forwarded to the finishing department. Blanks may be linished using our taper sensing centreless machine, or they may go straight to trimming and jointing.

The linishing is a process used to give a smooth finish and key for painting. About half our blanks are coated with colour finishes, and about half go out with the natural unground finish.

Linishing is a simple but critical process. We have the best machinery and expert Mike Helliwell supervises this process. The aim is to remove the resin ridges but not affect the action of the blank by removing carbon.

Rod sections are fitted together after precision centreless grinding the male end of one section to fit into the female of the section above. Blanks are then ready for building.

This is a simple account of what we do. The excellence is in the raw materials, the design and finally the subtleties in production. Our staff turnover is virtually nil, our team ambitious and dedicated. It all adds up to a better fishing rod. And all the blanks are made here in Liverpool in sight of my office window.


	Table from Toray http://www.toray.com/