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im6,im8,im10 rods

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Well which are you, 6, 8, or 10? ;D

I suppose the difference between im6 and im8 is im2. The same would also be true between im8 and i10.

Actually, I THINK it represents the modules in each blank.

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what is the difference?

I've always related it to the strength of the graphite. It takes less IM8 graphite to build the exact same rod in IM6, and even less graphite in IM10. Less graphite means a lighter more sensitive rod.

Of course, the extremely thin walls in the highest grade graphite rods like IM10 or Sic VI and others can make them more vulnerable to breakage. 

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Really good question.

I would like to know that too. Is there a standard out there for measuring stiffness to weight ratio? There's IM-? and ?-million modulus and SC-? (St Croix), ... ad finitum, most that basically amounts to jargon.

The fishing industry needs some standards. Or maybe anglers need them and the industry would rather not have to answer to a number that might control buyer decisions, to the exclusion of other important factors. Like what's happened with the number of bearings in reels -that one's become almost meaningless.

I'm an adult, I can handle it: How about a standard for rods? And then how about line!

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As I understand it there is no standard in Rods as it relates to the "IM" numbers.  One companys IM8 could be the same as another companys IM6.  I however am not an expert on this, I just read it somewhere.

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As I understand it there is no standard in Rods as it relates to the "IM" numbers. One companys IM8 could be the same as another companys IM6. I however am not an expert on this, I just read it somewhere.

You've read it here.  It's been covered before. 

It's also covered in the Bass Articles in the menu drop down above.

http://www.bassresource.com/beginner/bass_fishing_rods.html

Essentially the IM rating is meaningless since all rod manufacturers build their rods different.  A cheaply made IM6 rod can easily weigh more than a more expensive IM6 rod made by another manufacturer and also be much less sensitive. 

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they are absolutely meaningless, unless you are comparying one company's rods, example the clarus to compre. There is no industry standard for the amount of graphite that must be present in the blank to garner the rating. My BPS Crankin sticks are glass/graphite composite yet they carry the im6 rating. Are they IM6? Not purely. Stick with a reputable manufacturer and do your comparisons within their line, a IM7 rod of one company may be a IM6 in another, or even worse IM10, or 80 million modulus in another. Some companies take an average strength of the graphite to make their ratings, others find the strongest fiber and rate the whole rod from it. Again there is no standard and they are pretty meaningless.

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Good articles. Thanks for those. They help.

Here's the take-home message I heard:

They tell me I'd like to see the modulus and strain ratings for the material used for rod line/model. After this is out of the way, then we can talk power, action, and cosmetics.

What am I missing?

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I have posted this many times here. For those that can't find it in the search here ya go....

It was posted on the rodbuilding site a few years back, by a top notch rod builder,

Andy Dear

Lamar Manf.

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.advancedcomposites.com/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 All!!   

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And another thing being overlooked here. If one was better than another, how do you go about telling if someone hasn't just stamped IM6 or IM7 on the rod and it's really an IM2?  ;)

You certainly can't prove it, right!

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The epoxy matrix that holds the rod fibers together and the scrim quality that improves the rods hoop strength is where the rubber meets the road. The actual fibers haven't been improved since the 90's when the need for improved aerospace fibers dropped off. Virtually all rods are built on the same fibers, how well it's put together into a blank is where the true quality/cost is.

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Well, after reading this most informative thread, I don't feel so inadequate because I REALLY like a couple of my antiquated IM6 rods.

Tom

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I agree totally. people have been catching fish since the beginning of bass fishing on equipment that is so far behind even the least expensive rod's technology today. I logged over 500 fish last spring through this summer on some $49 allstar classics from academy. don't get me wrong, i love technology and the direction it's trending, its just that i think people tend to over analyze this area of our sport. maybe i have this outlook because i don't have an obscene amount of money to dedicate.  but if i did, i'd have a rod box full of cumaras

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I have owned and still own some of the original standard (not even IM6) graphite rods from Castaway. (and some HG40's) They are some of the best feeling rods that I own.

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