Bamboo part 4
Split cane: In the fourth installment of Harry Boyd's series on bulding bamboo fly rods, he describes the tools and processes of binding strips together and then heat-treating them in some sort of oven.
The Global Fly Fisher Guide to Building Bamboo Fly Rods
Part 4 - Binding and Heat Treating
Strips rough tapered to triangles, ready to be re-ordered, bound, and heat-treated.
The first Garrison style binder I made. The first wind of string is being applied.
As the name implies, a four string binder applies four wraps of thread ot the bundled rod sections in one pass. Most are powered with some sort of electric motor.
A close view of my current Garrison style binder as the second string is being applied.
A close-up of the four string binder at work. The wheels on which the thread spools are mounted turn in opposite directions. Each spool must be individually tensioned.
My Cattanach style oven, heated with a mica strip element. Notice the two well-bound bundles of strips.
An oven built and used by my friend Kyle Druey.
A heat gun based oven made and used by Timothy Troester.
Don Anderson's heat treating oven.
Tonkin bamboo is the common name for arundinaria amabilis, or "the lovely reed." Scientific classification treats bamboo not as a wood, but a grass or reed. For over a hundred years rod makers have debated the best way to enhance the natural characteristics of bamboo in order to best fit it for fishing rods. In our last installment, we progressed to the point of having at least eighteen strips split, straightened, and rough-planed into un-tapered, equilateral triangles. Before those strips are planed to their final tapered form they must be bound in hexagonal bundles of six strips and heat- treated to remove long sweeping bends and add spring and resiliency.
Binding six strips together into the familiar hexagonal shape can be as simple as cross wrapping by hand with cotton twine, or as complicated as using a counter-rotating, electric motor powered, four string binder. I have used a variety of methods and will only describe the general process briefly. Every binding method begins with arranging your strips in the firing order of an old six cylinder, internal combustion engine. Heating in this unusual numbering order places each strip in a different sequence than its final arrangement might dictate. Any unusual stresses will be counteracted by neighboring strips, resulting in a final product which is straighter and easier to work.. First arrange your strips by the numbers 1-6 on your workbench.
Second, re-arrange the strips by number 1-5-3-6-2-4. Carefully arrange the strips into a bundle with the enamel side out. A wrap of masking tape at each end and a couple between the ends will hold things in place.
Cotton thread is used to bind the strips before heat treating. For hand binding, you can use 100% cotton embroidery twine purchased at your local discount store. Though the embroidery thread works quite nicely for binding while heat treating, it is sort of fuzzy. When you later bind the strips during the gluing operation, that fuzz makes a mess. Many rod makers use 100% glace cotton 16/4 and 12/4 thread. "Glace" means that the thread has been polished to remove the fuzz. The numbers 16/4 and 12/4 refer to the particular weave of the thread itself. Still others use cotton upholstery thread, or buttonhole twist cotton thread from local cloth stores. I purchased a huge spool of glace cotton thread from Russ Gooding at http://www.goldenwitch.com/ which should last several lifetimes.
Under no circumstances should polyester or cotton covered polyester threads be used. We will shortly be heating these strips at temperatures up to 375*F, and polyester will burn, leaving strange looking charred stripes around the length of the rod.
Binding by hand requires some method of tensioning the thread. Some makers use a large fly tying bobbin. Others use guide-wrapping tension devices. Still others place the spool of thread in a vice, and keep tension using only hand pressure. Begin by making four or five half-hitches around the butt end of the bundle of strips. Remove the first layer of masking tape, and start turning the section, wrapping the thread in a consistent pattern with about 1/4"-3/8" between turns. Remove each piece of masking tape as you progress from the butt to the tip end of the section. At the tip end, again make a few half-hitches to keep things tight, then cut the thread. Again starting at the butt end, half-hitch the thread and make a second cross wrap of thread in the opposite direction. Wrapping each section twice helps prevent twists.
After cross wrapping each section, spend a few minutes getting things straight and twist free. If you heat crooked and twisted sections, the oven sets those bends and crooks. Locate any twists by sighting down the section against a well-lighted white background. Hold the twisted section firmly just above the twist. With your other hand give it a good firm twist in the opposite direction. Repeat as many times as necessary to get out every little twist. Next roll the twist free sections under the palms of your hands on a flat surface. The binding string adjusts itself well and holds each section perfectly straight.
Wrapping by hand works well, but is tough on the muscles in your hands. If you are planning to make more than a handful of bamboo rods, I strongly suggest a binder. I made a couple of binders based on modifications of Garrison's design, and recently acquired one of the four string binders. Good rod making books will have binder plans, and further information on building your own binder can be found at several internet sites, especially http://www.canerod.com/rodmakers/
One model I really like was developed by Tom Smithwick. Details and pictures of Tom's binder as well as several others can be located through the Rod makers site.
Though binders are not complicated pieces of machinery, no inexpensive models are available commercially. Goldenwitch sells a modified Garrison binder. Dennis Crockett in California has a four-string binder for sale priced at about $850.
Tony Larson from Minnesota produces a nice binder (and beautiful nickel silver rod hardware) for about $300. No lower priced alternatives come to mind, other than making ones own.
Using a binder accomplishes exactly the same thing as binding by hand, only with less hand cramps. Bundle your strips with the enamel side out. Half-hitch the thread (or threads) to the rod section, and either turn the crank
or start the motor. In a few minutes your strips are bundled and ready for the heat treating oven.
Almost all makers agree that some sort of heat treating is necessary, but deciding which regimen works best is not easy. Neither is determining exactly what heat treating accomplishes. Tradition teaches that heat treating makes bamboo stiffer and reduces the tendency of the rod to "take a set" or remain bent. Recent studies by Adam Vigil, Bob Milward, Ron Grantham, and Lloyd Cross have called into question much of the wisdom of bamboo rod making traditions.
To my non-scientific way of thinking, heat-treating bamboo accomplishes three things. First, heat treating removes excess water from between the actual cells of the bamboo. Second, excess water in the cells themselves is removed. Finally, some of the liquids within the cells of the bamboo changes structure, making moisture reabsorption more gradual. When those three things have been accomplished, the bamboo is better suited for building rods.
I am convinced that:
- Heat treating bamboo makes it much stronger in bending.
- The changes that heat-treating produces are permanent.
- Too much heat-treating is as bad or worse than none.
- Every rod maker must work out a heat-treating regiment for himself.
One major hurdle to overcome in building bamboo rods is finding a suitable oven for heating strips of bamboo up to five feet long. Please don't tell the folks in my Church, but I built my first several rods using the commercial convection oven in our Church kitchen for heat treating. Should you choose to do the same thing, please use the Church oven at some time other than when the church ladies are preparing Christmas Dinner.
Perhaps you can find a local pizzeria willing to let you use their oven. Better yet, ask a rod maker in your area to heat treat a few sticks for you. One advertiser in "The Planing Form" (a newsletter "for those who make and appreciate the split bamboo fly rod") used to offer to heat treat your cane for you. I've heat-treated several sticks for friends. Contact me and I will be glad to recommend someone in your area who might be
willing to help you out.
If you decide to build more than one or two rods, you will want your own oven. The most sensible design I have seen utilizes a furnace fan to circulate air, insuring that no "hot spots" exist, and avoiding the need to flip the sections end for end halfway through heat treating. A detailed description off Don Anderson's oven can be found at: http://www.canerod.com/rodmakers/tips/daoven.html.
Wayne Cattanach's book details an oven plan based on a 60" mica strip heating element. The oven I use is based on that design, although I am planning to add a recirculating fan soon. Bret Reiter makes and sells a similar oven. Many rod makers use ovens powered by the same electric heat gun used for straightening nodes. One such commercial unit is available from W.J. Senecal in Monson, Massachusetts. The Rod makers web site mentioned
above has several articles on building your own oven.
What should your heat-treating regimen be? Only you can definitively answer that, but I will gladly share what works for me. Most of my rods are flamed somewhere between light and dark brown. I then soak my strips in water for several days before straightening and pressing nodes. To remove all the excess water between the cells of the bamboo strips, I heat the bound sections in my electric element oven to 180*F - 200*F for three to four hours.
To remove some of the water in the cells and bring about the mysterious transformation of liquids and oils within the bamboo cells, I leave the strips in the oven, and turn the thermostat to 360*F. As soon as the thermometer reaches 360*, I start timing. The bound bundles are then heated at 360* for 12 to 20 minutes. Somewhere between 12 and 20 minutes, a distinct smell begins to emanate from the oven. As soon as things "smell right" I remove the bundled strips from the heat. I wish I could be more specific, but there is a feel for these things that only develops with familiarity and practice. That particular routine might or might not work for you. One good friend tells me that much heat with his setup produces only ash. He heat treats "like baking biscuits, 375* for 7 minutes, turning end for end at 3 1/2 minutes."
Once you remove the strips from the oven, store them in a dry place. Our next article focuses on the heart of building a bamboo fly rod -- planing the taper into the strips.