Splitcane rods are made from Tonkin bamboo, from a small corner province of China, since, roughly, 1910. It’s currently classified as Pseudosasa amabilis. Tonkin cane wasn’t always the bamboo of choice for making fishing rods. Several other bamboo species had been used before that, most notably Calcutta bamboo - Dendrocalamus strictus - imported by the British from India. Calcutta bamboo has shorter internodes, therefore more, and more pronounced nodes than Tonkin bamboo, has narrower culms and less dense vascular bundles (the so-called ‘power fibers’ of rodmakers’ speak), and is more crooked as well. So when Tonkin cane became available, the rod making community switched over quickly and completely. That’s not to say that no other bamboo species are used for making split bamboo rods - in Japan Madake (Phyllostachys bambusoides) is a popular material for light line rods, and in South America some local species are also used, such as Guadua (Guadua angustifolia), a giant bamboo species that is sometimes touted as the strongest bamboo in the world. A recent development is the use of Lô ô bamboo (Bambusa procera) from Vietnam - but the jury is still somewhat out on that one.
Tonkin culms emerge from their rhizome at their final diameter, grow in length for a few years, then start forming leaves, and die off after flowering, like most bamboos. Culms are usually from 2-4 cm in diameter with the largest ones reaching 5.5 to at most 6 cm - these are the ones that are normally selected for rod making. Bamboo culms do not get wider as they grow older or longer. The widest culms are quite rare, and are usually selected and separated right at the source, for special purposes, such as rod building. Thinner culms, up to, say, 38 mm, are traded as garden poles and used as feedstock for all sorts of bamboo products. Note however that the fiber quality of a 35 mm pole is not lower than that of a 50 mm pole. They only yield fewer strips, of a slightly stronger curvature. But if selected for density, quality and cosmetics, you can build cane rods from ‘garden poles’ that are equal to those made from preselected culms. Tonkin is usually dry enough when it arrives over here to start building rods right away, but it doesn’t hurt to store it in a dry place for a couple of months, to help acclimate it. If you do, you should make a check split, to prevent (further) spontaneous splitting during drying/storage.
Culms selected for rod making are usually 12 ft in length and are often sawn in half for transport and handling. The first step in making rods from culm sections is splitting, or sawing, them into appropriately-sized strips - large rod manufacturers like Hardy and Pezon&Michel would saw their culms, and there is nothing inherently wrong in sawing strips. For small-scale builders however, splitting is the simpler approach, with less waste, and a limited layout in equipment and shop space. With some careful planning, you can split 24 strips from a 50 mm culm - sufficient for 4 single-tip rods.
I use a heavy machete and mallet as splitting froe – note that splitting strips from bamboo culms requires a certain dexterity and experience; my very first pole resulted primarily in waste… For the last split, where you divide a 15 mm strip into 2 7.5 mm strips, I use a simple belt knife with a thin blade, to better control the split. After splitting, I use the machete to remove the nodal dams from the inside of the strips – I prefer doing that with individual strips rather than removing the dams from half a culm. I split ‘in the hand’, since I find that that gives me more control over the running split than other methods, such as splitting over a knife or nail fixed in a bench vice.
In contrast to sawn strips, split strips are never straight: splits find their own way through the bamboo, and oftentimes, your knife will wander as well, running to one side of the strip – this is what you learn to control when you split a lot of culms though. As such, the fairy tale that, in contrast to sawing, splitting carefully and exactly follows the ‘grain’, or fibers of the bamboo is just that, a fairy tale. In a split strip the power fibers do not necessarily follow the split surface. This already suggests that there is no major difference between sawing and splitting strips. Especially if you saw your strips slightly oversized.
After splitting, strips need to be straightened, to remove all the bends and twists, mostly through the nodes. You do this by heating a strip over a flame or paint stripper until the lignin (the ‘resin’ in which the bamboo ‘power fibers’ are embedded) becomes soft and pliable, making it possible to remove bends and shakes. After cooling, the strip will keep its new form. Next the nodes, where the vascular bundles deviate from their up/down orientation and make a bend into the nodal dam, need to be flattened – again by heating, then pressing in a vice. Following this, the nodes are staggered, so that no two adjacent strips have nodes at the same location, and strips are cut to final length, depending on the rod under consideration.
Now that the strips are straight and the nodes have been pressed, it’s time to turn the roughly rectangular strips into strips with a 60 degree equilateral triangle cross section. Once they are triangular we can then taper them, manually or with a shaper or milling machine to their final dimensions required by the rod’s design parameters and intended action. Rough beveling can be done by hand, but that is a rather tedious and backbreaking job, that doesn’t require high precision anyway, so is much better done with a machine, a rough, or initial beveler. Such a machine is easily made in the home workshop. and therefore quite accessible to a hobby-builder. Many simple rough bevelers are based on horizontally mounted routers with straight cutting bits, that cut the bamboo strip one side at a time. More elaborate machines work with special 60 degree milling cutters that cut both sides at the same time. And then there is the so-called Baginski beveler - popularized by German cane builder Rolf Baginski. This machine is based on a repurposed bench grinder on which one grinding wheel is replaced by a wheel with a 60 degree groove. The two sides of the groove are covered with coarse sanding tape, which will sand the strip into a rough triangular cross-section when a strip is pushed past the sandpaper. Before you feed your strips into a rough beveler, the remaining nodal ridges need to be removed. You can do this with a file, or with a plane. As long as you don’t damage the dense outer layer of vascular bundles, just below the cuticle or dermis (the ‘enamel’), it doesn’t really matter how you do this. Personally I prefer planing over filing.
After beveling, with the strips roughly triangulair, the enamel (or epidermis) of the strips is remover using a schraper – I use a vintage Stanley #80 model cabinet schraper. This transforms the outer surface of the strips from rounded (as it was in the culm) to flat, and reveals the ‘power fibers’. There are other approach to scraping; from single-pass tapering mills to exquisite Lie-Nielsen scraping planes (a copy of a vintage Stanley – originals demand north of $ 1000 these days), to a simple scraping iron or a reground plane iron. Because scraping does not totally flatten the node areas and always leaves marks on the bamboo surface, the strip’s outer flat undergoes a final smoothing step with sandpaper. Following that, the strips are ready for final tapering.
But first we need to temper – or heat treat – the strips. Heat treatment of bamboo strips was introduced some time in the first half of the 20th century. Heat treating makes for stiffer bamboo strips, resulting in faster rods, that are less prone to taking a set. Heat treatment increases the modulus of elasticity of a bamboo strip, by heat-modifying the cellulose fibers and other carbohydrate and other phenolic polymers. In that aspect is is in fact not so different from carbonization of synthetic fibers to make carbon fibre. Problem is that with carbon fibre, you’re carbonizing just the fibers; with bamboo you’re carbonizing everything, fibers, matrix, everything. So you need to make sure you don’t take it too far, destroying the material. Bob Milward (Fact, Fiction and Flyrods) and Wolfgang Schott (Bamboo under the Microscope, and Bamboo in the Laboratory) have done some research in the effect of heat treatment on bamboo, concluding that it does indeed increase modulus, but also weakens (breaking strain) the bamboo – so heat treating is a trade-off. Note also that a slight set in a bamboo rod is unavoidable if you use a rod for what it was intended for, and doesn’t influence its casting or fishing properties.
For tempering, the beveled, untapped strips are bound in bundles of six and put in a tube oven - note that short strips for multi piece rods or for nodeless building can also be tempered in a normal household oven. The strips are then heated to roughly 170°C and kept at that temperature for about half an hour. Since the strips also lose water, they need to acclimatize for a couple of days after treatment, to re-equilibrate with the ambient moisture level. If you don’t, you may run into trouble when final tapering, since the tapered strips may continue to reabsorb moisture after planing, changing in dimension. Or they may present troubles when glueing, especially when using water-based glues like resorcinol or urea-formaldehyde. When the strips are tempered and stable, it’s finally time to plane them to their design taper.
Before I started making my own bamboo rods, I was firmly under the impression that making split cane was all about the tapering step, and that if you had an (expensive) planing form and a block plane you were in business. How wrong I was. Final planing is only a small step in making a bamboo rod, and if done carefully probably not even the most difficult one – even though it is, more than anything else (with the possible exception of cane selection), the step that defines the rod’s action and quality. Of the 40+ hours that making a serviceable bamboo rod takes – from splitting to final varnishing, only 1 to 2 hours are spent taper-planing.
These days, almost all bamboo rod makers – essentially hobby builders, even if they make a living making bamboo rods – use a planing form and block planes for this step. The use of some sort of planing form dates from the beginning of the 20th century, but was popularized by the Garrison/Carmichael book and only became the predominant process with the demise of the large bamboo rod factories when glass fibre took over as a rod building material. A planing form is essentially a large steel bar, consisting of two halves connected together with push and pull bolts and kept in alignment by steel dowels. The inner edges of both sides are beveled with a tapered 30 degree bevel, together forming a 60 degree groove. This groove can be widened at regular intervals with the push and pull bolts, creating an adjustable groove that lets one set it for a specific taper. If you lay a rough-beveled bamboo strip in that groove and carefully plane it down to where the remainder exactly fits in the groove, taking care to regularly flip the strip to preserve the required angles for an equilateral triangle cross section, you end up with 6 identical strips that can be glued into a rod joint with the desired taper and action.
As you may have seen elsewhere on this site, these days I predominantly build rods with integrated bamboo ferrules - more specifically along the line suggested by Davide Fiorani, the Tapered Bamboo Ferrule. To make these – as well as to make follow-built bamboo sections – sections of the strips have to be thinned, from the inside. I’ve made four different contraptions for this process, and haven’t been happy with three of them (among these a dremel-router based machine and a thickness sanding table setup – see the blog pages). My current setup uses a planing table with rectangular grooves of different depth (reflecting the desired wall thickness) and a spokeshave with most of the plane blade ground away, so that only the section directly over the groove still cuts, and the rest of the sole of the plane rides over the surface of the table, once the bamboo has been reduced to the required thickness. This works both for hollowing the female ferrule section of a TBF, where the required wall thickness is 0.9 mm and for scallop hollowing of an entire section, where the intended wall thickness usually is around 2 mm. Because a female ferrule built like this has very narrow glue surfaces, these glue joints don’t have sufficient strength to withstand pressure from inside – when a male ferrule end is inserted. Therefore a TBF female ferrule has to be reinforced with a thread scrim over its entire length. Note that there are other alternatives to the classical metal ferrules, such as a separate sleeve made from glass fibre or carbon fibre, or a spigot joint made from carbon fibre.
Now that the strips are finally ready, we can glue them together into rod joints. These days, most rod makers use industrial epoxy resins for this, although in fact most wood glues, including so-called ‘white glues’ are suitable for rod building. A water resistant PVA glue would work well enough, even though it is not the best choice from practical considerations. The synthetic glues that have been developed for boatbuilding and airplane construction, such as resorcinol-formaldehyde and urea-formaldehyde resins are excellent glues for bamboo rod making, but are more demanding in use – especially in the area of working accuracy and glueing procedures. Good industrial epoxies, especially those that will improve upon heat curing, are much more forgiving. Classical hide glue is structurally strong enough but has too many drawbacks, such as sensitivity to heat and moisture, to still be viable.
To start the glueing process, the 6 strips are first bound into a rod joint with masking tape, which is then slit along one seam, so that the strips can be laid flat on the table while still being linked together. Next the strips are covered with glue, usually with a toothbrush, rolled together, the tape removed, and then bound under pressure with strong thread, either by hand or with a glue binding machine. The most common binding machine is the so-called Garrison binder, but I prefer a simultaneous 4-string binder modelled on the binders used by makers as Winston or Powell. After binding, strips are straightened and hung to cure. Modern resin glues can be cured at elevated temperatures, and with epoxies that actually results in stronger glue bonds. After curing the binding thread and any glue residue on the surface of the blanks is sanded away, resulting in a final blank. After final straightening this blank is ready to be turned into a fishing rod.
Traditionally bamboo rods are lacquered, with something resembling spar varnish. An alternative approach to finishing is impregnation, first developed by Wes Jordan at Orvis. who soaked his glued up blanks for multiple weeks in aqueous solutions of phenolic resins (sometimes identified as ‘bakelite’, although that is not strictly correct) followed by curing of the resin absorbed by the bamboo. I also impregnate my blanks, but in a vacuum process, using a methylmetacrylate resin, which is much more convenient in use than phenolic resins. Advantages of impregnation are a better protection of bamboo against moisture (although for water-shedding ability it’s best to regularly treat a fishing rod with a paste wax), an inherently matte finish, and no application or drying mishaps so often encountered with lacquers and varnishes - plus faster curing – once impregnated, the resin can be cured in a couple of hours in a heat-treating oven at ca. 100°C.
Another interesting alternative finish is using PU glue (‘Gorilla glue’) as a friction polish.
After coating the blank, the female bamboo ferrule is reinforced with thread wraps, usually undyed silk or polyester for most of the length of the wrap, with a final 5 mm wrapped in nylon thread. These ferrule wraps are varnished for integrity, which, if done correctly, renders the silk or polyester part of the wrap invisible. With the female ferrule securely wrapped, the male ferrule can be sized to fit. This completes the actual blank.
Following this, the blank is turned into a rod, by installing a reel seat, cork (or wood) grip, and guides, including stripper and tiptop. Guides are made in-house, from hardened steel. Strippers and tiptops are sourced commercially. At special request rods can also be wrapped with SiC (or even better: torzite) guides, for much increased wear resistance. Next is a signature inscription which will be varnished also, together with the guide wraps. All of these steps are identical to the steps required to turn a plastic blank into a fishing rod… Cork gries are shaped on the rod, while wood grips are preformed on a wood lathe. I also make the reel seat inserts myself, and some styles of sliding band reel seats are made in-house completely. Wood grips (mainly from Abachi, which is not much heavier than cork) are stiffer than cork so transmit vibrations during fishing better than cork does. Interestingly, wood grips are historically more correct than cork. Rods are then equipped with in-house produced rod socks, and can, if necessary, be delivered in a simple but sturdy PVC rod tube, or a nice hexagonal wood tube – at extra cost.
Henk Verhaar - Schroedinger rods
For inquiries: henk@buroverhaar.nl