Vietnamese Bamboo Analysis

[BigTJ]

Fluted rods compensate for the lack of dams in two ways. First they typically aren’t as aggressively hollowed as scalloped rods they will split otherwise - and the lack of dams is made up for with thicker sections at the edge of the strips. And by the way at least a few Winstons have blown up over the years by cracking on the flats.

I gave you the straight answer there really isn’t anything more to it than that. I guess maybe I could have started by asking you this - if the material at the neutral axis mattered that much why can a rod be hollowed quite a lot and end up with very similar casting properties / stiffness profile to an equivalent solid rod despite losing 20-30% of its weight? Or why are beams in a building shaped like an I? Or bicycle frames made out of tubing? That should hopefully turn the light bulb on.

Cheers,

John

Hello John,

I didn't ask to wind you up, I was really curious. And again, I am not an engineer. So thank you for your comments.

But before I finally let go I'd like to comment, that rodmakers do claim a change in casting properties by hollowing, namely making the rods livelier and a bit faster besides lighter. And yes, I noted that you said "similar casting properties".

Not wound up at all. Trying to give some examples. Your intuition isn’t “there” on the physics so trying to help you understand. Hope the info helped. Of course the casting properties change a little when a rod is hollowed but it’s not like the rod explodes or changes to something radically different. The differences are subtle, and generally good. That wouldn’t be the case if the central fibers were really important. What matters most is the stiffness and other properties of the material in say the outer 1/3 of the fibers - there are differences in bamboo species and some of the rodmakers picked up on that - some more than others.

Like to fish - bamboo rods, both solid and hollow, break when slammed in car doors, or broke over one’s knee. That’s the equivalent situation to the level of required forces to break a bike frame & design considerations to keep them from buckling. So not really relevant to the conversation if fibers on the neutral axis of a fly rod matter much to a rod’s casting properties. The point is that you can make a bike frame out of a tube and it can be quite large diameter with thin walls. That wouldn’t be the case if strength at the neutral bending axis was required.

Cheers,

John

[henkverhaar]

As BigTJ points out, node work can be a nuisance, although I have found ways to make it quite easy. Would nodeless rod sections be better? I don't think so in a functional sense. Convenience for the rod maker is, of course, another story.

Tend to agree - it's primarily about convenience - especially if nodeless doesn't include splices ;-)

[henkverhaar]

I have some of the material, and am in the process of duplicating an existing rod. I intend to bring them both to the Catskill gathering. I am in the very early stages, and have rough planed a bit of it and split up more than I need for the rod. Initial impression is that the material takes some force to split, but is straight grained and seems to have little tendency for the split to wander. Several times I got to a .750 dimension, meaning I had to split in thirds to get the .250 wide strips I like for rough planing. That can be tricky with Tonkin, but went quite nicely with the Lo o material. Another early impression is that the enamel layer seems thicker and tightly adhering. It took more effort to scrape it off using a cabinet scraper, as I have done for years with Tonkin. I hope to get a lot more work into the project in the next couple weeks, and will update this information then.

I tend to agree with your observations.

How are you duplicating the existing rod - just a copy of the existing taper, or are you somehow adjusting for differences in MoE - and if so, what numbers do you use?

[henkverhaar]

From what I understand and maybe someone can verify: the Lo o is only being sold as "internodes" not full or even half culms? So if the builder needs say 48" sections lengths or longer he has to build node less? Sadly I can't use it if that is true.

Peer sells individual internodes for who wants to try some, culm sections with 2 internodes (about 2 m in length) for 'normal builders' (I ordered 10 2-internode sections last year), and 6 internode sections for (I have no idea for whom - shipping would be a bear...)

[Peer]

I realised that my description of the lengths at which Lồ ô can be acquired was not clear. For a better understanding, I will explain how Lồ ô was harvested: The culms were cut by internodes and not by length. An internode is the piece between two nodes. One to two Lồ ô internodes are enough to build a multi-piece rod. Lồ ô can be bought in pieces of 1, 2 or 6 internodes.

A culm is about 66 feet (20 m) long and consists of 30 to 40 internodes. The long internodes (27 inches/70 cm and more) start around the 10th internode. Harvesting was done from the 10th internode upwards, when it was at least 70 cm long, until the 16th internode. Most of the harvested pieces, which consisted of 6 internodes, were then divided into pieces of 1 or 2 internodes. In most cases, each internode after the 10th to 16th internode is longer than the previous one. After that, they gradually become shorter again until the end of the culm.

As overseas shipping costs have risen incredibly, sending DHL parcels with 2, 8 or 18 individual internodes is the only viable option. Within Europe, the option of sending pieces with 2 or 6 internodes remains, however for Great Britain, a VAT registered company and its EORI number are required.

The next dispatch from my warehouse will take place in June.

In April I will give a talk about Lồ ô at the Corbett Lake gathering and in September at the Catskill Gathering. If you are coming there and want to buy Lồ ô, I can bring the required internodes, I just need to know 1.5 months in advance. If you have any questions, I will be happy to answer them.

[PMD18]

Very informative,great article.
Thanks

[RMorrison]

If only somone built hollow rods with a nice light straight grain wood inside as an aid to strength and casting properties…like a Port Orford Cedar or something…

[BigTJ]

Come on Rich let’s be realistic for a second… oh wait!!!

[mjm6]

Peer,

I won't be at either of the gatherings but would be interested in trying some of this bamboo later in the year so I was wondering if you were intending to get a large shipment sent over and then deliver personally at the gathering or would you be able to drop some with a shipper once you have arrived?

I can wait, so no need to ship from Europe but if the shipping from Europe is going to be easier for you to accomplish, then I'll order some through that route once I am ready for some bamboo.

I want to make some very short/small rods for very small stream fishing and these would allow a single rod section with no nodes which is an interesting prospect.

[mduval]

From what I understand and maybe someone can verify: the Lo o is only being sold as "internodes" not full or even half culms? So if the builder needs say 48" sections lengths or longer he has to build node less? Sadly I can't use it if that is true.

Perhaps not in NA yet, but Lo o is available in two internodes with one node segments giving strips roughly 54 to 78 inches, give or take. Plenty long.
I only had internodal segments and I purposely chose a Pezon et Michel taper with offset ferrule for my first Lo o and Tonkin pair of rods. I build mostly nodeless rods and I needed to scarf the Lo o to get my 52.5” tip section and 39.5” butt section. The scarfs on the butt section were mostly to get me that extra length needed during the process of making the blank.