break my 1st blank performing an static test before building it

[oc1]

The glass or carbon fibers do not stretch or compress much at all, so it is the resin that provides the elasticity.  This allows the fibers to get pulled apart on the outside of the curve, and crammed together on the inside of the curve, as the resin elasticity to allow the rod to bend without breaking and then return to the original shape.

Fiberglass has some elasticity.  Carbon fiber has very little elasticity.

Before the fibers can break, they have to pull free of the bond between fiber and resin.  It's irreversible so once that bond is broken the rod will be softer (have less stiffness/rigidity/modulus).  Old fiberglass rods were notorious for getting softer with age due to failure of the fiber-resin bond.  Carbon fiber rods tend to just break instead of becoming softer.  The difference is the elasticity of the fibers.

-steve

[oc1]

Lower strength carbons mixed with high strength carbons offer more flexibility and less prone to hoop strength failures.

The issue at the end of the day, is that few blank manufacturers will publicise the exact carbon contents of their blanks, for obvious commercial reason. Additionally, the general angling public like to see lots of big numbers in advertising material, thinking they are getting 'better' products.

It's not really strength Jeri, they use carbon fiber materials with different stiffness or modulus.

When rod manufacturers talk about IM6 or IM8 they somewhat describe the type of carbon fiber being used.  The IM number is a shorthand way expressing stiffness/modulus.  Strength is expressed using the number of individual fibers in the bundle.

-steve

[Jeri]

It's not really strength Jeri, they use carbon fiber materials with different stiffness or modulus.

When rod manufacturers talk about IM6 or IM8 they somewhat describe the type of carbon fiber being used.  The IM number is a shorthand way expressing stiffness/modulus.  Strength is expressed using the number of individual fibers in the bundle.

-steve

In the surf world where I do a lot of my work, most blank manufacturers work in strengths, like T24, T30, T36, etc, rather than IM numbers. We also have worked with certain blank manufacturers as to the resin load per particular strengths to get other variables in performance from the end product.

A difference is also noted between European blank manufacturers and those down here, where the Europeans will add more E and S glass in to the mix of their designs to achieve softer tips for some designs, while others opt for full carbon construction. The whole aspect of trying to generalise what, how and why with blanks is a minefield, because there are just too many variables to be considered for any generalisation to hold water.

[steelfish]

wow, nice, lets continue guys, lets get more pages than Benni's Luck thread 



nice to see you over here Jeri, our in-house surf fishing master rod builder.

so, let me ask you, on your long surf rods, whats your method for the static test to find the locations for the guides and how much drag, force or weight do you use?

[jurelometer]

The glass or carbon fibers do not stretch or compress much at all, so it is the resin that provides the elasticity.  This allows the fibers to get pulled apart on the outside of the curve, and crammed together on the inside of the curve, as the resin elasticity to allow the rod to bend without breaking and then return to the original shape.

Fiberglass has some elasticity.  Carbon fiber has very little elasticity.

Before the fibers can break, they have to pull free of the bond between fiber and resin.  It's irreversible so once that bond is broken the rod will be softer (have less stiffness/rigidity/modulus).  Old fiberglass rods were notorious for getting softer with age due to failure of the fiber-resin bond.  Carbon fiber rods tend to just break instead of becoming softer.  The difference is the elasticity of the fibers.

-steve

Oops.  You are right. Somehow I forgot that glass fibers are made of glass  . Glass is an amorphous solid, which means that the atoms don't bond in any repeating pattern. This means that there is no directional difference in stiffness or elasticity for glass fibers. It stretches the same as it bends.  I don't think that it affects  my description of how rods fail, but it does help explain why fiberglass rods are often able to bend more without breaking.

In terms of wearing out,  if the fibers had similar adhesive bonding properties, the more stretchy fiber should stay bonded longer.  Fibers are just half of the equation.  Although the same resins can often be used with the different fibers,  cheaper versions of polyester resin tends to be used with pure fiberglass rods, while carbon fiber tends to be matched with fancier epoxies, often with some additives that promote adhesion.

-J

[oc1]

When the fibers stretch their diameter shrinks, helping them to pull away from the resin.  When cured, polyester has less elasticity than epoxy.
-steve

[Jeri]

wow, nice, lets continue guys, lets get more pages than Benni's Luck thread  

nice to see you over here Jeri, our in-house surf fishing master rod builder.

so, let me ask you, on your long surf rods, whats your method for the static test to find the locations for the guides and how much drag, force or weight do you use?

The quick answer is that we don't!

We get a lot of information from the blank manufacturer about the blanks they produce, and that normally includes the 'test curve' of the blank, a rating load in kilograms, to pull the blank round to full 90 degrees of curvature. They have the rig to test the progressive loading of the blank design, holding the blank horizontally, and progressively loading the tip.
This not only gives a loading at the tip, but a defined curve of the upper portions of the blank, which is recorded, and used for comparisons to other designs.


This sounds at odds with the majority, but as nearly all the rods are being developed of casting to distance, the loading is more representative to the actual final rating of the rod, or the power needed to motivate the rod in a cast. A lot of this comes from the fact that the majority of blanks have a stiff to very stiff bottom end, and the design and length of that near parallel section is more determinate of performance. A rod that bends/flexes between the hands during the cast, is usually as effective as wet spaghetti for pure distance. In some extreme cases, that parallel or very inflexible section might be as much as half the total length, which basically changes the blank design to a combination of lever and spring, rather than just a spring.

Testing to determine the guide position is a little more towards an educated first guess, then trial and error to make small changes to overcome any problems that might be encountered during new rod test casting. Though this is not as random as it might sound, as we have found that guides on the first half of a rod for spinning reels are basically redundant, so concentrate from mid-point upwards. Taping guides in place and then test casting, chalking the line side of the blank to find any spots where line is hitting the blank during casting. Typically for a current 14' design we would be using 9 guides + a tip, though we are using a scheme which is a hybrid between Low Riders and KR. With multipliers (conventional) reels, again the stiff butt section negates the need for many guides close to the reel, as again distance achieved is more the focus than some form of static test. Pulling a curve with line threaded through taped guides only serves to avoid points where the line might be touching the blank, but doesn't necessarily point towards casting performance. Though again with our older designs of multiplier surf rods, a 14' rod might well have either 8 or 9 guides + tip.

Personally, we have found that the distance between reel and the first guide for spinning reel rods is critical, and usually at odds with the guidelines published by Fuji, but then our blanks with stiff lower sections are the main factor there, we don't have to accommodate the flexible lower half of the blank. Typically, Fuji suggest 120cm between the reel and the first guide, where we operate at somewhere between 180cms and 210cms, with experiments currently being done with a couple of rods set at 235cms, all set on rods that are 430cms long. This kind of tallies with the test curves of the blanks, where 8kgs would be typical of a medium strength level blank, were anything up to 18kgs would be the test curve for a very high skill powerful casting blank. The old adage of surf cast, that 'if you can't bend it, you can't send it', is still very applicable.

Not perhaps what you were hoping to hear Steelfish ...............

[oc1]

chalking the line side of the blank to find any spots where line is hitting the blank during casting.

Thank you Jeri.  Good stuff there.  And thank you for the tip about chalking the rod. 
-steve

[Jeri]

I think that one of the elements that make surf rods different in behaviour to say normal spinning rods, is the element of line speed. A few years back looking at the spool speeds of multipliers, we determined that line leaving a reel on a reasonably powerful surf rod, is at times approaching 100 mph, or 180km per hour. Pretty fast, and this makes some problems go away, but uncovers others, that might not normally be present in a shorter spinning rod situation.

|This again is where I feel generalisations are not a fruitful source of guidance.

[steelfish]

Not perhaps what you were hoping to hear Steelfish ...............

actually thats what I wanted to hear, what the real pro on rod building are doing when building a quality rod, so, now I have your input and its pretty interesting if I ever build a long surf rod.

before getting into rod building I bought a used 13' custom surf rod, its a rainshadow SUR1505, material is graphite rx7 (their code I think) and its as you said, pretty stiff on the lower half and all the 7 guides on the top half.
Im not using it pretty much because in this zone of the Sea of Cortez you will catch the same small fish if you cast 130yds with a great surf rod or 60yds with a light 7ft surf rod or heavy salmon rod.
in the lower part of the Baja Peninsula (la paz, Cabos, etc)  is where the good quality long surf rods shine catching big roosterfish, dorados and big Pargos from the surf.

[gstours]

Alex buddy I can relate to your tears and kapows!   I broke one jig rod that was 30-50 rated and was supprised test it in the yard.  I remember the sound and feeling that followed.  It toowas a bargain compared to the hi end compared ones that I,d love to have.   Building my own rod is more satisfying and that's what we do.   Butt....
   After reading this article several times my feelings are the rod blank even with the line taped to the tip should have not broken until the butt to tip angle exceeded 90 degrees.   A bargain maybe?
  Probably a defect in the blank that showed up.   But you are much better off with your bend test first ...
      I always test my blanks and sometimes adjust the guides before finishing.     Best of luck. 💫

[philaroman]

if you position rod/blank horizontally & suspend weight from tip (line or no line)

YOU CAN NEVER EXCEDE 90 DEGREES -- that's just how gravity works

I thought you start w/ an empty bucket;
gradually add weight 'til you get to 90*;
AND STOP -- that's your TC rating

[JasonGotaProblem]

Im reading thia thread wondering if I'm doing something wrong. I see my fast taper rods clear 120 degrees or more on a regular basis. Knock on wood really hard, but I've never had any trouble.

[gstours]

Alex, this year I was a witness to 3 rod explosions, and okuma, a penn, and a China no name.
  This saying,  why did it happen .?   We will never know.   This is an interesting place and I,m learning as we go.    Alex you are a very talented man,  I envy your patience and work.    Gst

[Jeri]

I think that it is often overlooked, just how potentially fragile carbon composites can be, sure immense strengths for such thin wall construction and light weight. However, even the slightest knock of the wrong sort can compromise a blank, and then cause a catastrophic failure when loaded.

We often get folks coming into the shop with rods that have broken and tales of "I was only jerking to pull for a break" or some such similar occurrence, but on close inspection often it is a clean break symptomatic of a knock to the side of the blank, and then the subsequent failure. In the case of brand new blanks, we just don't know how it has been treated prior to arrival on our work bench, or in the case of factory built rods, how was it handled during all the stages until it arrived in your hands.

All that without it having been a manufacturing fault.