Resin

[VGB]

I just took my dog for a walk, I have a terrier not a springer because springers are associated with an evil cult. It should be possible to get the resin from trees to make Paul's rods.

I understand part of the resins job is to group and solidify the graphite fiber cloth. Now I've learned we have different quality of graphite cloth. That the resin contributes little to the rod's modulus...is that true for the rod's stiffness profile. Read an article that claimed the resin will "limit lateral/overall wobble."

I'm fairly sure that Lasse's rod will have a fair amount of overall wobble

I still think that the answers at Posts 15 and 16 from Steve and Paul provide all of the information that you need. As Steve described, you need a match between the properties of the fibres and resin so that they behave similarly in tension and compression, otherwise the bond between the two will fail and your rod will break. As was mentioned, if the resin is too stiff it will also be susceptible to impact damage. Paul's post majors on the material properties that are required for production which are also major considerations. If you want to understand rod properties without getting too wrapped in science, the Itinerant Angler podcast with Gary Loomis is great:

http://www.itinerantangler.com/blog/pod ... with_gary/

Regards

Vince

[Lasse Karlsson]

I’m surprised they’ve gone down the phoney marketing route. I thought a few of their rods that I tried were rather good (even if they did explode in my hands).

Cheers, Paul

Remember when they got someone from the military working on dampening on nuclear submarines to help make their rods dampen better? Turned out they put a neoprene sleeve under the Cork
Seems like the guy from the submarines is back working for them

https://youtu.be/qJ32sjo3Osw



Cheers
Lasse

[VGB]

Maybe someone should come up with a new strap line such as "It doesn't matter what rod you buy, learn to use it asshole" It would be up there with great advertising campaigns such as "Boxy but good"

https://www.youtube.com/watch?v=gUlfWmdCW-k

[Lasse Karlsson]

Volvo mmmmh

[Graeme H]

"It doesn't matter what rod you buy, learn to use it asshole"

Mind if I steal that for my new forum signature Vince?

[VGB]

Of course you can Graeme but I was going to charge Paul for “Hot Torpedo, get hand jobs from beautiful women you hardly know”

[Torsten]

Can we get back then to the topic please? I think the infinite discussion about the spring energy should be put in a separate thread. Thanks.

Another good information ressource is the book from Don Phillips, "The Technology of Fly Rods", Frank Amato Publications, 2000. There you can find aspects that we also discuss here (E.g. rod building, composites, spring vs. lever).

I'd cite from there about rod damping:

"[..] My damping tests of dozens of fly rods have shown that internal material damping is not very significant. Rods made of synthetic materials such as boron, graphite and fiberglass had damping factors of 0.020 to 0.031, while cane rods had damping factors of from 0.023 to 0.061. Although the difference in damping factors between cane and synthetic rods is indeed significant, all rod materials can be considered to have very low internal material friction or damping; only 2 to 6 percent of fully damped systems. [..]"

--

What I'm missing in most articles are concrete examples and measurements of actual rod materials.

Another question is, if the rod manufacturer actually work with resins; it seems to me rather that they buy prepregs from the carbon fibre manufacturer which contain already the resin.

One mentioned manufacturer is Toray (Japan), I've found another: SK Chemicals (Korea)
https://www.skchemicals.com/download/TD ... ver2.0.pdf

You can sometimes see the packages of used materials in the factory tour videos on Youtube

[Merlin]

That the resin contributes little to the rod's modulus...is that true for the rod's stiffness profile. Read an article that claimed the resin will "limit lateral/overall wobble."

Lou,

I do not know what is meant by “lateral/overall wobble”. Does it refer to rod stability (not a question of material)? Does it refer to damping (small for composites, better if the rod is fast)? Or does it refer to twisting?

I take the simple example of unidirectional composites. The flexural modulus is largely dominated by the fibers characteristics (I gave you a rule of the thumb). There is another modulus (shear modulus) which is important for twisting, and it is largely dominated by the resin characteristics, not the one of fibers: imagine you twist a bundle of spaghettis, if you glue the spaghettis altogether, the structure will better resist to twisting and that will be due to the glue. To resist twisting you can use carbon fibers at 45 degrees from rod axis and that will overtake the resin characteristics.

Beyond material characteristics, rod stiffness profile is all important (as well as rod mass profile), and I would say that it is relatively more important than the material itself. Material can help reducing the overall mass of the rod, especially in the butt sections.

Merlin

[gordonjudd]

What I'm missing in most articles are concrete examples and measurements of actual rod materials.

Torsten,
It is straightforward to get an "effective modulus" value for a blank given its measured dimension and spring constant values. Robert Haun also derived an effective modulus value of a blank based on measurements of its design profile and its measured fundamental frequency value.

Even though the fibers in the graphite sheet material may be rated at some value, when you back into a modulus value based on how much it deflects for a given tip load you find the resulting effective modulus value to be much less than the modulus of the graphite fibers. It is assumed that the effective modulus is isotropic (uniform) throughout the cross-section of the varying radius values of the rod in this simulation.

Many years ago Dr. Spolek sectioned a rod to get its inside and outside diameter value along the blank. Using those values you can calculate how the rod will deflect along its length for a given tip load and then back into an effective modulus value that matched the predicted curve with measured values as shown below.


You can see the Ey modulus value needed to get that match was 99Gpa (14.3Mpsi) even though the IM6 graphite material was rated at around 40 million psi (275 Gpa). Robert Haun did a similar reverse engineering exercise based on the measured frequency measurements of a rod and came up with an effective modulus value of around 10.6e06 psi for an IMX blank that had a rated modulus value of around 47e06 psi for its graphite fibers.

Haun stated the tensile modulus of the epoxy resin matrix in use in 1996 was only .4-.6 million psi.

The effective modulus of a blank is not something you are likely to see in a marketing blurb.

Gordy

[Lou Bruno]

That the resin contributes little to the rod's modulus...is that true for the rod's stiffness profile. Read an article that claimed the resin will "limit lateral/overall wobble."

Lou,

I do not know what is meant by “lateral/overall wobble”. Does it refer to rod stability (not a question of material)? Does it refer to damping (small for composites, better if the rod is fast)? Or does it refer to twisting?

Merlin
I have no idea. I read a review for a Sage rod. The reviewer used that phrase, shows how confusion sets in.

Lou