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Discussion Starter · #1 ·
What is the difference between IM6 and IM7 blanks?

Thanks,
 

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The basic rod is made from either fiberglass or graphite. This material is woven into what looks like sheets of cloth. The finer the weave, the faster the action. The weave is measured in modulus. Fiberglass rods have a modulus of 6 to 13 million and graphite rods are from 33- to 60-million modulus (ie: IM6 has 33,000,000 and IM7 has 42,000,000).

A high modulus rod would be stiffer, faster, lighter and more sensitive, but will also be more brittle, much like the difference between Plexiglas and glass. All rod blanks are not created equal. A quality blank will be lightweight and engineered for a specific action.
Here is a link to a good article that explains the difference too....

Graphite Rods

I hope this helps!!
 

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I'm sure other guys can give a more detailed explanation as I'm no expert, but my understanding is that it has to do with the stiffness of the rod. The higher the modulus (IM7 being higher than IM6, etc.) the stiffer the rod. This supposedly leads to great sensitivity and a lighter rod, but also makes the rod more "brittle" or prone to breakage.

I did a little poking around out of curiosity, and here is a link that explains it in much more detail than you would probably want:

http://www.nybass.com/forums/printthread.php?t=11157&pp=40

(Good info, even if it is in a trashfish forum...)
 

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Discussion Starter · #4 ·
Good info. Thanks guys.
 

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As with anything, don't go just by modulus. I have noticed cheaper and cheaper rods advertising higher and higher modulus (I keep spelling that wrong) ratings. I had been warned that some companies will stick a label on there that isn't legit, all their blanks are not created equal or something. So although it is a large consideration, especially in rods where sensitivity is important, it isn't like that rating is checked by anyone.
 

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modulus of the graphite weave is one thing.... the effective modulus of a rod is something else. a lot of the rod's responsiveness and strain rate is dependent upon the resin composition that they use to lay up the rod, and a lot of rods have fiberglass scrim... so the amount of fiberglass scrim compared to the layers of graphite also change the rod's action. then finally is the geometry of the blank (taper), by changing geometry, you can get a lot different feel.
 
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