So if you can't tell from other posts, I love TN grips on spinning rods, and would use them on every build if I could convince customers. So many guys don't want anything to do with 2 pc. rods because of sensitivity loss - so I have been asking them why do they insist on 2 pc handle assemblys?

It actually gets their attention!!!!! Give it a shot.

OK - there is my tiny little contribution for the day - I'll call it my $.01 worth, as $.02 may be over priced.

Marc

Tell me more about sensitivity loss in a 2-piece rod. I've not heard that one before.

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Hey Tom, in all the sensitivity testing and analyzing that has been done, has anyone actually tested one pc. vs. two pc. rods. I have read all the articles in Rodmaker regarding sensitivity, did I miss this part? Any info would be great, as I get clobbered all the time by guys that won't look at two pc. rods, even if it may be a better choice for them.

The fact that the rod has two pieces isn't automatically going to decrease sensitivity. Now any changes in material or size at the ferrule can and probably does have some impact on sensitivity but we'd be getting into a realm that is likely going to be far outside what any fisherman could feel with his hands. I'm not saying that vibrations won't be reduced, only that the amount by which they would be reduced isn't likely to ever be noticed by the fisherman. The idea that a 2-piece rod can't be as sensitive is similar to the old myth about how they couldn't be as strong as a 1-piece rod.

Most of these type myths originate not because somebody tried something and found it to be so, but rather because they heard somebody else say it and after a while it just tends to become "fact."


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Marc,
Any two piece rod is going to weigh a little more due to the ferrule and therefore be less sensitive than an equivalent one piece rod that has the same power, action and is constructed from the same materials and has the same basic design.
In my judgment there are a number of disadvantages to multi-piece rods and only one advantage but the advantage is a big advantage for some people. That big advantage is obviously that they can be broken down for convenience when transporting them.
There has been very little in the way of actual measurements made of the variables that affect sensitivity that I am aware of. In fact, the measurements that a couple of the articles in RodMaker are based upon are the only actual measurements that I am aware of that have been made.

Tom,
We must have been typing at the same time.
One piece rods being more sensitive and inherently stronger are not myths. I would agree with you that with modern ferrules the difference is sensitivity and strength is less than was the case in the past with older ferrules but there is a difference. One piece rods are both more sensitive and stronger. The question is how much more sensitive and how much stronger.

If 1-piece rods were necessarily stronger, then the 2-piece models would all be breaking at the ferrules in the deadlift tests. They don't. They break in the butt section just like the 1-piece versions. They're every bit as strong as the 1-piece models save for perhaps some very cheap multi-piece rods that might break at the ferrule. But the decent multi-piece rods don't break at the ferrule so that comes out of the equation insofar as which is stronger. The ferrule isn't a factor.

Above I said that that the 2-piece models wouldn't be as sensitive. The difference, which I think you alluded to as well, may not be enough for fishermen to really be able to detect in the naked hand.

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Tom,
I am afraid that your dead lift test does not prove very much relative to the ferrule because during the dead lift the majority of the load is transfered to the butt section well past the ferrule. With a dead load test the butt is normally parallel with the ground so naturally the break will be near the butt.
Where a rod breaks is a function of the butt angle. If you remember I did some testing of this on old blanks several years ago when we were having this same discussion. I can make a blank break anywhere that I want it to break by changing the angle of the butt relative to the ground, the higher the angle the further toward the tip that the break will be. The area just in front of the ferrule is inherently weak due to a phenomena called stress concentration. Stress tends to be concentrated or focused just in front of the ferrule. As a result many rods break a few inches in front of the ferrule. The ferrule itself does not break, the rod breaks a few inches in front of the ferrule but the break is caused by the ferrule. In other words the break would not occur if there were no ferrule.
With any two piece rod the most common break is going to be 8 or 10 or 12 inches from the tip. This is due to high sticking, again this is a function of the angle. The next most common break is going to be just in front of the ferrule a few inches. This is due to stress concentration caused by the ferrule.

Emory,

Making a blank bread "where you want it to" has no bearing ferrule strength. When we speak about blank strength I'd assume we'd be talking maximum deadlift capacity before failing, between two blanks, one of them a 1-piece model and the other a 2-piece model. You can make a 2-piece blank break a couple inches ahead of the ferrule and I can make the 1-piece counterpart break in exactly the same area. Neither is a test of how strong either blank is, only that we can make them break where we want to and that doesn't have much if anything to do with how strong a blank is. Manufacturers test blanks for strength by deadlifting, not forcing them into angles of abuse. The former tells them something - how strong is the blank. The latter only tells them what they already know - that anybody can break any blank if they try hard enough.

If we're going to talk about breaking strength when blanks are abused and used incorrectly, we can toss all of this out the window because it's no longer a function of how strong a blank is, but how someone is abusing it.

The average fisherman who's afraid of 2-piece blanks has heard that the ferrules are inherently weak and will break. They aren't and won't, at least not any moreso than any blank might, regardless of how many pieces it might have. It is rare that you'll find a decent blank that sports a broken ferrule. I fish mostly 2-piece rods and have never had one break at or near a ferrule. But I don't abuse my rods and if I did, they'd break regardless of whether they were 1 or 2 piece models.

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Tom,
I would not say that ferrules are weak to the point that rod builders should be afraid of multi piece rods. However, all other things being equal, one piece rods are stronger than rods with ferrules.
It absolutely is not rare to see a rod that is broken because of the ferrule. I see it often. As I said before, the ferrule itself does not break but it is the cause of a break a few inches in front of the ferrule.
Like it or not stress concentration exists. You can minimize it with a good ferrule design but you cannot eliminate it entirely.
You know most of the rod manufacturers. If you know one of the rod manufacturers that is using Finite Element Analysis in their design ask them about it. With Finite Element Analysis it will be very obvious where the stress tends to increase.

I have a degree in mechanical engineering from Duke University. I'm fully up to speed on what causes stress and where it tends to concentrate based on the design of various structures.

Since those rods were obviously not used correctly - they'd have broken in the butt area if they had been, I'd stop short of saying that they're weaker than 1-piece versions. I've seen plenty of 1-piece rods broken in that exact same area - to what do we ascribe their failing? I'd ascribe it to the same thing that broke the 2-piece models - poor fish fighting technique, not weakness. My 2-piece rods will lift just as much as any of their 1-piece counterparts without failing. They're just as strong.

Now if you want to talk about having something in the rod that a fisherman could more easily mis-use then I'll concede that it might be easier for a fisherman to break a 2-piece rod than a 1-piece, maybe.



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If ferrules are not a weak point in the rod, then why do we wrap the ferrule up to as close to the end as possible?

I wrap all the flipping sticks I build at the point were the fore part extends through the handle section for the same reason. Because I have always believed it to be a weak point, if this is not necessary then I will stop to save the weight.

But I'm inclined enough to think it is a weak point and keep wrapping them until I see some evidence to prove other wise.

They're wrapped to avoid splitting the ends. This is where failure of the ferrule itself would most likely start.

I wrap mine to prevent a possible split out, although most manufacturers internally reinforce their ferrules these days and say wrapping isn't really necessary. I wish they'd instruct whether to do it or not on the blank package.

If you deadlift the maximum capacity for any blank, 1 or 2 piece, it should break in the butt area or lower 1/3rd of the rod. It isn't likely to break at the ferrule - at least no more so than a 1-piece counterpart breaking at that same location. Correctly used, fishing rods transfer that kind of load to the butt well before the areas further up the rod are loaded to the point of failure.

Nearly all fly fishermen use multi-piece rods - very few 1-piece fly rods have ever been made. But there has never been a rash of breakage or any sort of inherent problems with these rods. If the ferrule was a weak point and was causing unnaturally high rates of failure, multi-piece rods would never have hung on for very long.

I'm sure some are afraid of multi-piece rods and won't use them based on a fear of breakage at the ferrule. It's their loss - they wouldn't have any more problem with the 2-piece rods than they do with their 1-piece models.


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I'm going to add something here because I think we may simply be on different pages. I'd maintain that 2-piece rods just as strong as their 1-piece counterparts. But I'll concede that a 2-piece rod might be easier to abuse to the point of breakage than a 1-piece model which suffered the same abuse (extreme angle - high sticking) in the same area. Nothing is ever going to be idiot proof, beyond a doorknob, perhaps.


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Edited 1 time(s). Last edit at 11/26/2007 07:03PM by Tom Kirkman.

Interesting thing about wrapping the female ferrule - the only place where you ever really see a split out occuring is on the older, cheaper tip-into-butt models. The ferrule wrap was originated for use on those type rods, which are inherently bad about split-outs due to that terribly awful design. The practice carried over to later spigot and oversleeve ferrules as time went on.

I don't think I've ever seen a tip-over-butt ferrule actually split, although most of the better ones are internally reinforced.

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I have just such a repair that's come in!

Steve,
The ferrule itself is not the weak spot. The weak spot that is the result of the ferrule will be just in front of the ferrule.

Tom,
Are you really suggesting that lifting the butt of the rod to any angle higher than parallel with the ground like dead load testing is done is abuse??? That seems silly to me and certainly is not the way rods are actually used.
I do not think that you are "fully up to speed on what causes stress and where it tends to concentrate based upon the design of various structures" or you would not be arguing the position that you are arguing. Any time there is a stiffening, even a slight stiffening as with a ferrule, in a tubular structure like a rod blank there will be a concentration of stress just in front of the stiffening.

In fishing, Emory, in fishing!!! Line's out an an angle, so your higher but angles are a bit moot. If the line goes down straight below you, or under the boat, what do you do? Hold the rod at an elevated angle?

Tom,
Here are a couple of things that I found on the Internet that might interest you. The first quote came from a sight called Stress Concentration the second quote came from Wikapedia. I studied electrical engineering so I do not have the mechanical engineering texts to refer to.
"Any discontinuity changes the stress distribution in the vicinity of the discontinuity so that the basic stress analysis equations no longer apply. Such "discontinuities" or "stress raisers" cause local increases of stress referred to as "stress concentration".
"A change in cross sectional area is one type of discontinuity. High local stresses can cause the object to fail more quickly than if the change in cross sectional area were not there".

Ted,
That was one of my points. When fishing you do not hold the rod like it is held during dead load testing. The rod is almost always held at a higher angle. This higher angle will tend to make any break occur farther up the rod or nearer the tip, sometimes around the ferrule.