Graphite composite versus fiberglass

[Gandolf]

Hi Ray,

I watched a video that showed a group of folks discuss fly rod breaking. Among them were folks who dealt with quality control complaints from customers of rod companies. They had to deal with broken rods.

The consensus was that the overwhelming number of rods were broken near the tip. As an illustration they put a relatively heavy weight on the line through the rod, and then lifted up the weigh, in fact lifting it until the butt section of the rod was pointing about straight up, and the rod tip was pointing straight down toward the suspended weight. The bend in the rod was primarily in the butt and lower mid section, and by comparison the tip section was pointing straight down toward the weight and was not bent at all, since the weight was such that it had straightened out the tip section of the rod. Thus in this test it showed that under very heavy loading the real stress of the load on the rod was on the butt section and lower mid section, it was not on the tip.

The fellows who had done the testing found that the main source of broken tips was a bunch of small hits to the rod with such things as bead head flies, etc. The cummulative effect of a bunch of small small hits damaging the fibers and resin over a period of time eventually lead to failure of the rod when one spot got to the point that it would fail to handle the strain and break.

It was a very convincing discussion and demonstration.

Regards,

Gandolf

[sagefisher]

Speaking of breaking rods, a friend of mine is a die hard bamboo rod person. He owns a number of boos, several made by the same person who made one for me. Anyway, my friend was at a show last year and someone was selling bamboo rods. He asked if he could cast one of them. He likes to and can cast a lot of line (he cast 90 feet using my rod and did so easily). So, he stripped out a lot of line and started false casting and broke the rod. The seller supplied him with an other rod, (bad mistake) and my friend also broke that rod when he had a lot of line out. Obviously the seller needs to make a better bamboo rod.

Larry ---sagefisher---

[Bobinmich]

An old article on boo vs graphite.

http://www.hatofmichigan.org/uploads...romthepast.pdf

Bob

[Bobinmich]

Oops.

I think I found a mistake in Harry’s paper.

From Wickapedia "Toughness can be determined by measuring the area (i.e., by taking the integral) underneath the stress-strain curve and its energy of mechanical deformation per unit volume prior to fracture. The explicit mathematical description is:

Energy/volume= the integral from 0 to failure of σ dε

Where ε is strain a σ is stress

Another definition is the ability to absorb mechanical (or kinetic) energy up to failure. The area covered under stress strain curve is called toughness.

If the upper limit of integration up to the yield point is restricted, then the energy absorbed per unit volume is known as the modulus of resilience. Mathematically, the modulus of resilience can be expressed by the product of the square of the yield strain times the Young's modulus divided by two."

The curves shown by Harry are wrong because he assumed the failure stress is equal between the different modulus’s. It is not.
E.G. Do the math and the IM6 the Modulus of resiliance is essentially equal to the S glass. So the lower modulus does not have a theoretical advantage as stated.

[tedshuck]

Speaking of breaking rods, a friend of mine is a die hard bamboo rod person. He owns a number of boos, several made by the same person who made one for me. Anyway, my friend was at a show last year and someone was selling bamboo rods. He asked if he could cast one of them. He likes to and can cast a lot of line (he cast 90 feet using my rod and did so easily). So, he stripped out a lot of line and started false casting and broke the rod. The seller supplied him with an other rod, (bad mistake) and my friend also broke that rod when he had a lot of line out. Obviously the seller needs to make a better bamboo rod.

Larry ---sagefisher---

I have only broken two rods. One when I slipped and fell on some rocks. I had not yet learned to sacrifice my body for the rod...
The other one was an Orvis Silver Label 4pc 8wt rod. I was lawn casting it and it broke just above the middle ferrule. The ferrule was tight and the break was about an inch above where the butt section would have reached, so I chalked it up to a manufacturing defect. The rod was replaced without a problem. Defects do happen and it is good to have a good warranty when they do.

Ted

[Bobinmich]

Ted,

I broke a 9 wt. Silver Label in exactly the same way at exactly the same point. I think it is a design flaw in that series rather than a manufacturing defect.

Bob

[tedshuck]

Bob,
Thanks for the info and idea that it was a design flaw in the rod. I was really surprised when the rod broke and have never really felt the same way about Orvis rods since. The new Hydros and Helios rods are getting great reviews though. A friend used the replacement Silver Label rod on a multi-day float in Alaska to catch numerous silver salmon, so the replacement seemed ok.
Regards,
Ted

[Jackster]

Some rods don't take to being bent a certain way. I've seen several rods break when the owners were stringing them up and a knot caught on the tip section, in freeing it they bent the tip back on itself and 'snap'.
High performance rods need to be treated as such IMHO. Loomis once said he could build a rod that wouldn't break but no one would buy it.

[Bobinmich]

The late JC would always remind us that more rods are broken while stringing than any other way. He would tell us to aways set the rod butt down on something forgiving and walk the line out to the end.

Bob