I know all the arguments re spine and straightest orientation of blank. I happen to spine because , I guess I am lucky, I have never received a crooked blank, and it is so easy to do so. But I am nervous when the spined orientation does not line-up with the orientation that gives me the "cleanest" straight up-and-down oscillation of the two top sections of a fly rod. Does anyone have any thoughts re that - or even better any science concerning oscillation??
Thanks,
Herb

Herb,

I know I'm still a rookie, and for that you can cast my thoughts off with a grain of salt. But, here are some of my thoughts. The blank for my first rod is a bit crooked, to the point that it has an inflection point (where the curve changes direction, kind of an "s" shape), and the spine was not very pronounced, in fact it seemed to have a couple different spines. After playing for a while with guides at various locations, I decided on the straightest axis as the way to go. It is aesthetically pleasing, and leaves me with very good performance.

I really buy into the idea that there is no wrong way to align the guides in regards to the spine. As a bass fisherman, I am usually making side-armed casts, or casts at funny angles to avoid obstructions and what not, so I am rarely casting along the same axis of the rod. So it is virtually impossible to align the guides with casting in mind. Ultimately, the line controls the blank in a fishing situation. The line will want to settle into the curve of least resistance.

Aside from determining the resonant frequency, what do we do with a fishing rod that mimics the small oscillations for the tip of the rod? Do you find the axis of best oscillation with or without the guides attached? Once the guides are on the rod, this axis may move unless the guides are absolutely perfectly aligned, as you are changing the mass distribution along the blank. Locating this ideal axis of oscillation is much the same as finding the spine, as you are finding a curve that the blank relaxes into when put under stress. The fact that this is done dynamically would lead me to apply a slight amount more credence, but not much more, to this method than spining the blank, but in use we don't use a fishing rod in this manner. We put a significant load on the blank when casting, and deeply load the blank on occasion when fighting fish. The tip oscillation test doesn't ultimately reflect what we do with the rod in the end. Not to mention, the axis of best oscillation might "move" as we flex the blank more deeply, just as the spine might "move" as we flex the blank more deeply. These movements can be attributed in some amount to the fact that the blank does not have a linear mass distribution, due to the construction techniques. Ultimately, we arrive at the same place with the line dictating the flex of the rod in a fishing situation.

So, does it really matter? At this point to me, NO. But, I will continue to play with each build until I determine that my way is completely satisfactory to me.

Oh, and some question for Emory if he happens to see and respond. How deeply do you flex a blank to measure the resonant frequency? Also, how quickly does the blanks nonlinear behavior become apparent? I will have to play a little to see for myself, but thought you might have some rules of thumb to compare to.

Joe



Edited 1 time(s). Last edit at 05/02/2008 01:24PM by Joe Vanfossen.

Once you put guides on the rod both the spine and the oscillation thing go out the window. The lever arm effect of the guides easily overcomes any spine effect so I don't bother with that. If you use the oscillation thing, put the tip top and few guides on there and you'll see that the rod will oscillate straight up and down with them due to the weight of them wanting to travel straight up and straight down. So for me both of these techniques have nothing to do with an actual fishing rod, just a naked rod blank and I've never fished with a naked rod blank.

The only actual tests I've read seem to indicate that using the straightest axis is the way to go. I know others use other methods and that's fine but I build on the straightest axis and it seems to work the best for me all the way around.

I have read many times, from people who know way more about rod building than I do, that the spine is an effect and not a physical thing. With that being said, why would it be that important? A blank really only does two things. It stores energy when acted upon by an external force or it releases that energy when the external force is removed. If that is what you are referring to as oscillation then I don't see what difference the spine orientation makes on casting or playing a fish. Guide spacing and size is going to effect the performance of the blank to a more considerable degree than the spine ever could. And, if you are always going to build on the spine then you will eventually have some rods that point in a direction other than straight. I respect other peoples opinions on the importance of the spine, but for me it is "much ado about nothing".
Lynn

Very well said, Joe (and Bill & Lynn)!! I build on the straightest axis.

Mike (Southgate, MI)
If I don't want to, I don't have to and nobody can make me (except my wife) cuz I'm RETIRED!!

I personally build on the straightest axis for two reasons:

1. I agree with the school of thought that straighter is better, and that "spine" makes no difference. I determine which way the rod is bending, and align my guides on the opposite side to counteract the bend with the guide weight.
(I build fly rods, so the guides hang down).

2. I believe MOST customers don't really know or care, but if they look down their new rod and see it bending any way but in line with the guides, they'll question the quality of my work.


Walt

In my case of building UL blanks, some spine are quite stiff and I like to use the spine on and off axis to change the power of the blank a bit. It's small but its there. A bent blank won't allow me to do that as I need to build on the straightest axis. So, I do prefer a straight blank so that I can build on whatever axis I prefer.

Mo

My initial oscillation test was, in fact, done on a naked blank. I deflected the blank upward untill I felt enough resistance to stop the blank from flexing any more - about 13". To test some of the above theories, I just did the same test with guides attached - However, they are light guides -REC s/f recoils and a REC recoil tip-top.
When I "snapped" the rod with the tip-top and guides oriented in the perfect ocsillation position determined before, the tip described a perfect up & down motion.
When I rotated the blank to the spined position - about 20 degrees difference - the oscillations were in a circle.
I do a lot of fly casting with 9' rods as well as bait casting with short fast GLoomis GLX or IMX (6') rods. The residual oscillations of a short casting rod is prob meaningless. But, I think, any residual motion left in a fly rod - especially in circles can only be detrimental to a cast. I know that some blanks will dampen much faster than others. You do not want a fly rod 's tip to continue bouncing all over the place after the line is uncoiling on delivery.
Herb

Well, here we go again.

We use effective spine. I'm not going to get into all the stuff above, nor the stuff that has been posted on many other threads on this BBS about this subject. I'll just say that's what we do, and it works for us.

Uncle Russ
Calico Creek Rods

Not everyone is on the same page here - spine is never stiff; spine is the axis that offers the least resistance. What Mo is talking about is the straightest axis - that's where you generally find the most powerful axis.

We know that spine has nothing to do with rod stability - that's not in question. I've done enough work with a mechanical casting machine to know that spine has nothing to do with casting accuracy. Thus, I build on the straightest axis, concave position, belly down, tip and butt up.

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It works for us too Uncle Russ...............

The spine doesn't matter, that's why it works no matter whether you bother with it or not.


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What Tom Said.....lol...............straightest axis

Laying your guides on the effective spine is equivalent to laying your guides on the weakest part of the blank. Why would you do that?

Anthony Lee

Anthony,
ASSUMING that the spine is relevant, and as you see here it may not be, but assuming it is - If you attach the guides to the concave side of a fly blank, the stronger (stiffer) side of the blank will be in use to deliver the fly line on the forward cast. If you attach the guides to the convex side then the stronger side will provide the more effective backcast. Some casters will tell you that the backcast is the most important part of the cast because it sets you up for a better forward cast.
Herb

There's a problem with even that, Herb. In most cases, the strongest and stiffest axis of a blank are not opposite each other (okay, rarely they are, but only rarely). So if you put the guides on the spine, or opposite it, the strongest axis is most likely still going to be somewhere off to the side, usually about 70 to 110 degrees off from the axis the guides are on.

It is a common misconseption that in one position you have the softest axis and in the other you have the stiffest axis. But in reality, these two are rarely 180 degrees apart.

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Tom,
I noticed that with a new blank I just received from Andy Dear. It had a really strong spine in one orientation and fell off a cliff in about 40 degrees. My prior comment was meant to be in general terms.

My original thread was really initiated to find out if oscillation was a valid method to determine guide placement assuming all other variables like spine and straightness were inconsequential and therefore were ignored.
Herb

I wish I could tell you. Frankly, I don't see what difference it makes though because once you mount the guides, the direction of oscillation will change.

Try the oscillation test with the naked blank. Then mount the guides somewhere other than on the same plane that the naked blank oscillates in. Now try it again. This time, the blank will oscillate in the plane you mounted the guides on.

Just not sure that it makes any difference, but it certainly won't hurt anything if you do things that way.

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Some manufactures have blanks more along the lines of 180 degrees aparts, and others don't. Depending on how they are built apparently.

Mo

I'd wager that far less than 5% have the softest and stiffest axis directly opposite each other.

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