Question For Rod Builders

[Sam]

Once upon a time we had rod blanks that were IM-7s.

Then the best graphite rods were IM-8s.

Today we have IM-9s.

So what is the highest IM number can the manufacturers go to?

Just wondering how sensitive a rod can be built without injuring its power base.

Should we hold off for IM-100??????

[MarkH024]

The Mars rover is bringing back a batch of indestructible material. It will be the IM-infinity.

No seriously that's a good question. Curious to hear what's to say about it. Always enjoy your posts Sam.

[Tony Monticelli]

there always going to have something new / different and or improved..

i like when things are advertised as better in all directions and your like how is that possible this makes no sense sounds more like it better in half those directions and worse in the other half and usually thats the way it ends up.

[Sam]

Here is the response I received from the G. Loomis people. More to follow once they give me the followup.

"Let me gather some information and I can come back to this for you. IM is the modulus rating. The main factors are density and weight to strength. The IM rating system is not as common once you get out of the lesser expensive rods most of the time. Companies like G. Loomis and others don’t boast an IM rating. It tends to be an inconsistent manner for rating the rods."

[Delaware Valley Tackle]

IM is kinda like number of bearings in a reel. It's not meaningless but by no means tells the whole story. It is also not a scientific standard either. The modulus of the graphite in a given company's IM rating may differ from anothers. A blank consists of the carbon fiber graphite, scrim, resins and sometimes finish. The combination of materials along with mandrel taper and wall thickness all come together to make a quality rod blank with exceptional stiffness and strength at minimum weight.

[BobP]

Here's a fairly simple description of carbon fiber IM numbers: http://www.calfeedesign.com/tech-papers/grades-of-carbon-fiber/

IM is basically a measure of carbon fiber stiffness and rod IM specs are not very meaningful because so many other things go into a rod blank that are as important to its performance, strength,and weight. IM numbers were popular in rod advertising in the 80's and 90's. That has declined as more consumers become more knowledgeable about rod technology.

[Crookedneck]

DT & Bob gave some good info. Currently there is no grading scale that is all inclusive when it comes to this. I think a lot of it is marketing. One companies IM7 or 8 can be totally different than the next. So too can the powers & actions. DT hit the nail on the head when he said taper, material & thickness all affect a blanks construction

[.RM.]

This was posted on the rod builders website http://rodbuilding.org/list.php?2 a few years back, and posted here many times by me..

Here goes again...............

Good evenin' folks,

I may be about to open a SERIOUS can of worms with this thread, but what the heck.....here goes anyway. Being in the blank distribution business, I get asked A LOT about the construction and makeup of the various graphite rod blanks that I sell. And, I have to say that whenever somebody asks me about modulus I just cringe! Here is why; It seems that about 90% of the folks that email me want to know what the modulus is of the blank(s) they are considering buying. When I ask "Why do you want to know that" they can't really give me an answer....they're just convinced that higher the IM rating is better. Here is how the conversation usually evolves:

Mr. Customer: What modulus is that blank made from?

Andy: Well, if you must know, it's about 40million Msi

Mr. Customer: What does that mean?

Andy: Well, it means the blank is made from the material you have come to know and love as IM6

Mr. Customer: Oh, that's too antiquated...I only fish with IM7 and higher.

Andy: Really? Did you know that the difference between IM6 and IM7 is not the modulus it's the tensile strength?

Mr. Customer: Really?

Andy: Yeah REALLY!

Mr. Customer: Eh Hhhmmm....erreer, uh, oh....well uh....well Bass Pro Shops says...

Andy: Forget Bass Pro shops...let's look at the numbers (at this point Andy whips out his trusty data chart that illustrates the differences between the different fibers that actually have IM designations). Here take a look at this. This comes from a chart put together by the folks at Hexcel (http://www.advancedc.../technology.htm)

The number on the far right is the modulus of the fiber, and the number in the middle is the elongation to failure or stretch.

Hexcel IM4 600 40

Hexcel IM6 760 40

Hexcel IM7 780 40

Hexcel IM8 790 44

Hexcel IM9 920 42

Mr. Customer: You Mean all this time I thought I was getting a higher modulus fiber with the higher IM rating, when what I was really getting is a fiber that stretches more?

Andy: Well, in some cases you are, and in some cases you arent. The fact is though that the difference between IM6 and IM7 is nothing in terms of modulus, and compared to IM8 it's only slightly higher. Wow...look at that IM9 actually has a lower modulus than IM8...go figure Now, many companies are using fibers with a much higher modulus, like 57 and even higher, however these fibers don't necessarily use the IM ratings. So, whenever you see a fiber with an IM rating...BUYER BEWARE! THE HIGHER THE IM RATING, DOES NOT NECESSARILY MEAN THE HIGHER THE MODULUS!!!

The point is this folks...just because you have a blank made from a high modulus fiber, doesn't means it's a good rod! And vice versa, just because you have a blank with a low modulus...even the original fiber blanks were made with (33 million) doesn't mean it's a bad or outdated rod. It's all about what the designer does with it.

I know there are some of you that may already know this, but judging from the amount of calls I get on a daily basis from folks who ONLY want IM7 or IM8, but can't really tell you why, I have to believe they don't really know what they are talking about at all. They've just been sucked into the marketing machine that leads people to believe that the higher the IM rating, the lighter and more sensetive the material, which is not always the case.

Be forewarned that there is A LOT more to graphite blank construction, performance, quality, sensetivity, weight etc... than just what modulus the fiber is. There are lots of other variables like flag patterns, and wall thickness, and resin systems, and mandrel design....It's all about the talent of the designer, and what he is able to do in terms of the sum of those variables...not just the friggin modulus!

Whewww...ok I feel better now...

My aforementioned explanation of modulus and IM ratings is by no means meant to be anything more than a brief primer for the folks who didn't realize what the differences with the IM ratings were. I hope this clears things up a bit, and I hope that some of you will chime in on this as well. Oh, here is a link to the Hexcel page for those of you who want to investigate the matter further. Do a search for IM6 and you'll get some interesting info. (if you're into that kind of techie junk).

[www.hexcel.com]

[www.advancedcomposites.com]

Now, this gives you some ammunition...next time you stroll into BassPro, and some yahoo tries to sell you a rod based on it's IM rating, ask him to explain to you why the higher IM ratings are better. When he replies by sayin' that the higher the IM rating means more sensetivity, less weight etc....just tell him that you have a blank at home made from IM2000, and see what he says.

Regards,

Andy Dear

Lamar Manf.

Tight Lines!

[dave]

I've seen that posted by RM several times over the years and it is always good to see.

[21farms]

Once upon a time we had rod blanks that were IM-7s.

Then the best graphite rods were IM-8s.

Today we have IM-9s.

actually, we're already at IM-10 with the shimano cumaras

[MickD]

RM, any comments on the new "nano tech" blanks that are appearing more and more now? Thanks