Over the last few years I have seen the production of rod blanks of ever higher modulus, supposedly for the purpose of permitting rods of comparable strength to be made lighter & lighter with less materials in the blank. I have seen some rods advertized with claims of a modulus of 81 million or more. Can anyone identify various sources of blanks for rodbuilders with this high a modulus? Also, does anyone know what modulus is claimed for the lightest of the Gatti blanks, and which model blanks have that material?

To go along with your question who determines what the modulus rating is? They may say it 33 mil. or 55 mil. One companys 33 seems to be diffrent from another companys 33 of the same length, power and action.

The design of the blank - diameter, wall thickness, etc., has as much to do with the performance and characteristics of the blank as does the modulus.

At one time, rod manufacturers were happy to use the modulus of the fiber in any particular rod line as part of their advertising. Many rod builders got the idea that the higher the modulus, the better the rod. Once that notion was dispeled, the advertising value of modulus went a bit downhill.

I have no idea what fiber the Gatti rods are made from. You might check with them and see if they'll fill you in. Some makers will, some won't. But again, modulus is only one part of a puzzle that has many pieces.

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The rod manufacturer does not make the fiber mat that carries the modulus rating. It might be interesting if Sharon Johnson or anyone else that has inside information would simply tell us curious rod builders what ratings of fiber are available from the people that supply the fiber material. I am not interested in higher modulus blanks. I would like a blank weighs absolutely zero, no larger than my little finger and guaranteed to never break no matter what the use. I bet if Tiger Woods needs a higher modulus golf shaft he could buy a company and manufacture the mats with a modulus of two zillion. Until something like this comes along my Rainshadows (41 & 53) will have to suffice. Gon Fishn

Paul,
One manufacturers number will be different than anothers.
There are a number of manufacturers of graphite prepreg, which is what the material including graphite, resin and scrim (every other layer) is called. The blank manufacturers buy the prepreq from these suppliers and can either buy their off the shelf prepreg or if they are large enough can custom order prepreg with any ratio of resin and scrim that they want.
The prepreg comes in big roles that are about 3 feet wide and 50 thousands of an inch thick. Usually what is called Standard Modulus has a modulus of elasticity of 33 million, what is called Intermediate Modulus has a modulus of elasticity of 40 million and what is called High Modulus has a modulus of elasticity of 50 million or higher.
However, this number is only for the graphite fiber and does not tell you what the actual modulus of elasticity of the blank is because it does not include the effects of the scrim, which can be graphite as well but is usually fiberglas, and usually has a lower modulus, the resin which always has a lower modulus and the finish on the rod which also has a lower modulus.
When the effects of resin, scrim and finish are included most blanks will have a modulus of less than half of what the modulus of the fiber alone is advertised to be.
Reputable manufacturers try to keep the resin and scrim content as low as possible but some do not because they buy it by the pound and high resin and scrim content prepreg is cheaper..

Why can't they start giving us a number of the finnal elasticity. In a sense what your saying is that the modulus number given by manufacture has no meaning due to all other variables. Can you explain IM6,7,8 is one company's IM6 rating better than what another company claimes to be IM8?

I doubt the rod manufacturers have any way to measure modulus of a finished rod. So what they give you is the modulus of the material they use to make the rod.

Travis,
There are two definitions of IM6, IM7, etc. that I am familiar with.
1. Because all of the graphites were developed for military and aerospace applications not for fishing rods: IM6 or 7 or 8, the I stands for Improved, the M stands for military and the 6 or 7 or 8 is the first digit in a 9 digit federal stock number.
2. The IM stands for Intermediate Modulus.

IM6 or IM 7 is a designation that the suppliers of prepreq use and it has meaning to them. IM 6 has a modulus of elasticity of 40 million and a tensile strength of 760 thousand psi. IM 7 has a modulus of elasticity of 40 million and a tensile strength of 780 thousnad psi.
However, some manufacturers desided to use this designation as a marketing tool and labeled their blanks as IM6 or IM7 if the modulus of elasticity of the graphite was 40 million even though they had higher resin and scrim content.

I agree with you that the blank manufacturers should supply the modulus of elasticity for the blank not for the graphite. I think that they will give Custom Rod Builders what they ask for and no one is asking for additional information. Personally I would also like to see tensile strength, toughness, strain energy and maybe even resonance frequency but I would settle for the real modulus of elasticity of the blank.
You can estimate it though if you are dealing with the reputable blank manufacturers, it is about one half of the number that is advertised.

Travis, Larry, Paul,
I would not get too carried away with higher modulus being the answer to everything. Tom is absolutely correct. The design of the blank is also very important and how high the modulus is should be is a function of the application.
For example, heavy duty boat rods should not be made from a very high modulus blank because it is not as tough. The reputable blank manufacturers know this and if you look closely at their catalogs you will see that boat rods tend to be from standard modulus, while say high performance fly rods are built of high modulus.
Having said that, I think that we as custom rod builders could make more informed decisions about what is appropriate for the application and the customer if we were given more information with which to make the decisions.

Travis,
They can determine it based on the prepreg that they purchase. Plus they can measure it. It's not rocket science.
However, there is presently no reason for them to. And the first one who starts to advertise a modulus that is half of what their competitors are advertising is at a competitive disadvantage.
A disturbing trend to me is that, I think that because some manufacturers are cheating, some of the most reputable manufacturers are not giving any numbers at all. They are only using Standard or Intermediate or High modulus.

I find all this technical material concerning modulus ratings to be quite interesting. Having taken strength of material many many years ago I vididly remember that the modulus of elastacity for steel was 30 times 10 to the sixth power. This number was quite usable to calculate the failure point of steel members when placed in tension. I would thing that the modulus that we are all referring to has also to do with failure of the fiber when placed in tension. Since we do not fail fishing rods in tension I am wondering if all the modulus stuff is applicable at all to the bending moment failure of a rod. Gerald this is my last comment before taking another long nap!! Gon Fishn

Bill,
You have a good memory. You are correct that the modulus of elasticity for steel, depending upon how it was annealed and tempered, is about 30 million psi, about the same as graphite. You are also correct that the modulus of elasticity numbers that are published are for tension modulus which is tension or the outside of the blank being flexed, compression is stress on the inside of the blank being flexed. There is also Bending, Torsion, Shear, Thermal and Bonding stresses to which a rod may be subjected. However, a physics major would tell us that they can all be derived from tension and compression and tension and compression are very close to the same.
You have a good memory but you didn't remember everything. As we apply more and more force to a rod it moves up the stress over strain curve (modulus of elasticity curve) until it reaches the tensile strength beyond which point graphite breaks. Steel, on the other hand, passes from elasticity into plasticity and takes a set.
I don't mean to sound smug, I had forgotten most of what I learned in Strength of Materials as well but I have had a renewed interest in the last couple of years and have been bonning up.
Now I think that I am going to go take a nap.
Also the calculations that you refer to were for a steel beam and were linear equations. A blank requires much nastier calculations as it does not bend or flex linearly.

All this information is great!!! How did you learn all that information. I wish I knew. Thank you for clearing up my mind on the whole IM6,7,8
question. Now I dont have to buy into the advertising hype and pay premium $ nothing.

Bill,

I'm just lurking and reading the words of wisdom that all of ya'll are laying on us. Interesting, but way over my head. Now you mention naps. Finally a subject comes up that this old retired dude is an expert in.

Later,
Gerald Mc

Gerald, Travis, Tom, Paul, Bill,
Tom has said it was OK for me to mention that I have written an article that will be appearing sometime in Volume #6 of RodMaker. The article covers the characteristics, properties and terms of blanks and the materials that they are made of, basically what we have been discussing here. Hopefully the article will help clear much of this up.

I'll be waiting!!