The tip of a rod doesn't rotate around in any manner that would affect the cast. It would require some pretty major manipulation with the rod to change the cast at that point.

............

Would building on the spine or straightest axis affect the CCS data?

Jonathan,

A lot depends on the type of build, number of sections in the blank, the material, and how straight the pieces are. For a 4-piece fly rod, spining the pieces has very little benefit, it is more important to use the straightest axis. Each each piece may have a spine that does not align with any of the other sections. The reason the spine is not as important is that the fly line follows the tip of the rod along the direction of the stroke so there is very little opportunity for the spine to affect the cast.

For a trolling rod or other heavy boat rod, the spine represents the strongest orientation so it is a good idea to spine the rod.

For surf-casting or distance competition rods, the building on the spine can improve the casting distance, albeit the difference may be marginal.

For casting and spinning rods (either one piece or multiple piece), you can use the straightest axis for aesthetic reasons, but I spine mine as I believe the spine affects the casting accuracy and have tested this theory extensively, but not scientifically. For example, I have found with my spinning builds, building with the spine on the right side of the blank, my casts drift left as the rod tries to release to the left. When I build with the spine on the top of the blank (opposite of the reel/guide side) my casts go where I aim as the blank tries to release in alignment with the casting stroke. When I have built a spinning rod with the spine on the bottom of the blank, my casts are shorter and erratic as the spine is resisting the cast.

For a bamboo rod, it is possible to use heat and some pressure (VERRRRY CAREFULLY!) to straighten the blank. Here, spining the rod could have some benefit, but the spine may not be in sync with one of the blank sections so may be a bit off center in each section. Aligning the sections so the spine is on the top of the blank can provide a marginal amount of added strength in the casting and fighting ability of the finished rod.

The bottom line is the rod typically looks better when built on the straightest axis, but may perform better when built based on the spine.

Rich

Richard Bowers Wrote:
-------------------------------------------------------
> Jonathan,
>
> A lot depends on the type of build, number of
> sections in the blank, the material, and how
> straight the pieces are. For a 4-piece fly rod,
> spining the pieces has very little benefit, it is
> more important to use the straightest axis. Each
> each piece may have a spine that does not align
> with any of the other sections. The reason the
> spine is not as important is that the fly line
> follows the tip of the rod along the direction of
> the stroke so there is very little opportunity for
> the spine to affect the cast.
>
> For a trolling rod or other heavy boat rod, the
> spine represents the strongest orientation so it
> is a good idea to spine the rod.
>
> For surf-casting or distance competition rods, the
> building on the spine can improve the casting
> distance, albeit the difference may be marginal.
>
> For casting and spinning rods (either one piece or
> multiple piece), you can use the straightest axis
> for aesthetic reasons, but I spine mine as I
> believe the spine affects the casting accuracy and
> have tested this theory extensively, but not
> scientifically. For example, I have found with my
> spinning builds, building with the spine on the
> right side of the blank, my casts drift left as
> the rod tries to release to the left. When I
> build with the spine on the top of the blank
> (opposite of the reel/guide side) my casts go
> where I aim as the blank tries to release in
> alignment with the casting stroke. When I have
> built a spinning rod with the spine on the bottom
> of the blank, my casts are shorter and erratic as
> the spine is resisting the cast.
>
> For a bamboo rod, it is possible to use heat and
> some pressure (VERRRRY CAREFULLY!) to straighten
> the blank. Here, spining the rod could have some
> benefit, but the spine may not be in sync with one
> of the blank sections so may be a bit off center
> in each section. Aligning the sections so the
> spine is on the top of the blank can provide a
> marginal amount of added strength in the casting
> and fighting ability of the finished rod.
>
> The bottom line is the rod typically looks better
> when built on the straightest axis, but may
> perform better when built based on the spine.
>
> Rich

Thanks Rich, I’ve got 2 going right now. Same blanks and going to be identical builds. One is spined, other is straightest axis. Gonna give them both a try and see if I can tell a difference. If I can, then the wife will probably end up with a new rod.

Well I have two questions one for each camp-----

If you build on the spine how do you manage to always cast on the same plane, inline with the spine on every cast? Do you never cast sidearm, pitch or flip?

If you build on the straightest axis do you find that you cannot hit the target you are casting to?

Mike Ballard Wrote:
-------------------------------------------------------
> Well I have two questions one for each camp-----
>
> If you build on the spine how do you manage to
> always cast on the same plane, inline with the
> spine on every cast? Do you never cast sidearm,
> pitch or flip?
>
> If you build on the straightest axis do you find
> that you cannot hit the target you are casting to?


To answer your first question, the line is going to follow the guides which are aligned on the spine. By definition, it doesn't matter how your arm is oriented when you cast, the line is going to be in line with the spine on a casting rod and the concave side of the spine on a spinning rod. The real question is does orienting the guides one way or the other add strength, or keep the rod from torque twisting, etc... That's the big debate I see between the two camps. I'm not a structural engineer and didn't sleep at a Holiday Inn Express so I'll leave that to others to answer/debate.

My answer to your second question is just my thoughts after a cursory pondering. If you build on the straightest axis, and that is indeed the strongest axis as some argue, then I would think, if anything, it *might* be a bit more accurate since you would arguably have less flex in the rod during the casting motion. That said, I think there are too many variables in the process of a cast to reasonably think that changing one variable is going to make that much difference.



Edited 1 time(s). Last edit at 01/22/2023 01:52PM by Daryl Ferguson.

I didn't interpret Mike's most recent post as questions he actually wanted answered. I may be wrong, and if I am, my apologies, but I see his asking of those questions, as a way of saying, think about it.

Daryl, you're right when you say that the line is always going to be in line with the guides on the rod, while casting. But the load on the rod isn't necessarily going to be in line with the spine, and therefore, the guides. Which I believe is what Mike was trying to get people to think about.

The lever arm effect of guides is present any time the blank is loaded. It's not only when retrieving a bait, or fighting a fish. It's there during a cast as well. So if you believe that the lever arm effect of guides will over power the spine, and you should, because it does, then the lever arm effect of guides is going to over power the spine during a cast as well. The lever arm effect will be greater and more easily felt with taller guides, but even with low framed micro running guides, the effect will still be present.

If you think about it .... if the spine actually made a difference in casting accuracy, then the only way you could make an accurate cast, is if the load on the blank was directly in line with the spine of the blank. And that is just not the case.

And as Tom has said many times ... the lever arm of the guides is what makes a rod torque in your hand. Not the spine. Build a spinning rod with the guides oriented 90 degrees to the spine of the rod and put that rod under load. The spine is not going to keep the guides from trying to go to to the bottom of the blank. It's the line trying to go in a straight line from point A to point B that is making the rod twist. As far as a difference in lifting power of the straightest axis versus that of the spine goes. From what I have read here on this site, the difference is minimal,

Personally, I'd be more concerned with guide placement affecting the lifting power to the point of breaking on a rod, than I would be with the orientation of the guides to the spine, or the blank's straightest axis.

It doesn't matter which camp you align with, any rod that is built will have some perceived unfavorable characteristic. Over time the user overcomes these deficiencies by observing how the rod behaves and adjusting for these deficiencies.

Accuracy is a function of the angler. The truth of this statement comes from real live events. I have been to many ICAST shows and there is always an area set aside for casting and rod handling. An area is set up with a rectangular pool 3 to 4 inches deep and there are a number of fishing rods provided for demo, testing and occasional contests.

It is amazing to watch the folks try their hand at casting different styles and builds. Mind you these folks have never seen or handled these rods before, but after some practice casts and adjustments, they handle them with remarkable precision. The obvious conclusion is that these folks have handled fishing rods before and learned to adapt to the rods characteristics and wound up working them accurately with little effort.

Even if the rod is built perfectly, anglers have to adjust their handling of the rod depending on the lure and line used, worms require a different effort than a crank bait or top water, etc. plus a whole host of other variables some of which are wind,rain, temperature and on and on.
There are hundreds of lures out there and I don't plan to build the perfect rod to handle each type of lure. I fish mostly from a canoe and bring two rods, one rod is strictly set up for worms and the other rod is used for any other lure imaginable and I use them both effectively.

Any rod that is a pleasure to fish with, it's a winner.

Posted by: Tom Kirkman (Moderator)
Date: January 21, 2023 07:26PM

David,

If you have the guides on the bottom of the rod the blank won't twist or torque, regardless of the spine.

Hi, Tom:

I only build and fish with fly rods so, per your point, the guides are always located on the bottom of the rod, so when fighting a fish the blank is bending via the pressure or force of the line exerted upon the guides. Given the nature of torque in a quality modern graphite tube is quite low, I am not too worried about torque in my fishing rod or my golf shaft.

I would have to say that the blanks I have purchased in recent years have all been pretty darned straight, a testament to today's carbon fiber and production technology. And the fly rod blanks I have purchased and have been building are all 4-piece, which I believe in some instances are rolled and baked in 4 different sections, rather than just a one piece mandrel rolled, baked and the blank cut into sections. If that is the case I would think the orientation of the sections, spine or bend in the rod will be even less significant, if significant at all.

I built a spine finding device more out of fun and DIY investigation than anything else. And will also give it a try on some golf driver shafts. I doubt I will perceive any difference. The data I have seen on golf shaft FLO (flat line oscillation) and its effects of shot consistency is mixed at best. Many will swear by it, others scoff.

We in fishing love to debate things like spine, swing-weight, carbon fiber modulus, guide tapering or not, nano-resins, guide types, single foot vs snake guides, size of stripping guides, etc, all which makes for good and fun discussion. At the end of the day I seem to catch a lot of fish regardless of how I build my fly rods, and I am more concerned about the quality and action of the blank, the components I put on it, and the rod's aesthetics than anything else.

Is spine location a concern in the way carbon fiber arrows are assembled? I know, not an archery forum.

No idea about arrows, but I saw this on an archery web site:

MAKING SENSE OF ARROW SPINE
One of the cool things about archery are the processes around it. On one hand, it’s science. You are dealing with physics, aerodynamics and energy transfers. On the other hand, it’s an art; a human working with machines. Your form, mental state and decision-making all factors into the equation of a perfect shot. Bowhunting and archery terms can get technical. Arrow spine is one of those terms that can seem technical on the surface, but can be easily explained. Here is what arrow spine means and how it affects the flight of your hunting arrow.

Arrow Spine

The spine rating of an arrow is simply a measurement of its stiffness. The same Easton arrow comes in a variety of stiffness: the lower the number, the stiffer the arrow. For example, a 330 arrow is stiffer than a 500 spine arrow. There are two kinds of spine (stick with us, we promise not to get too technical). There’s static spine, which is how an arrow reacts when an 880-gram (1.94 lbs.) weight is suspended from the center of the arrow. The arrow must be 29” in length and supported by two points, which are 28” apart. The number of inches the arrow deflects or bends X 1000 due to the weight is the spine size or measurement of an arrow. So, a 500 arrow bends .5-inches when the weight is applied.

Then there is dynamic spine, which describes the way an arrow reacts from the stored energy of a bow as it is shot. Too many factors determine the way an arrow is going to react when shot out of the bow, and because of the nearly unlimited variables in determining dynamic spine, Easton hunting arrows are measured using static spine. You can manipulate the dynamic spine of an arrow and make it act stiffer when shot from a compound bow by decreasing peak bow weight, point weight or the point/insert combination, using heavier bow string material or adding more strands to the string, heavier vanes, heavier serving material and/or nocking point and shortening the length of the arrow.

Ok, now that we’ve determined what the spine of a hunting arrow is, why is it important? If you do not have the correct arrow spine for your bow set up, you are going to get erratic arrow flight and poor shooting groups. Having the proper arrow spine is key to optimizing the grouping of your arrows and for the best possible accuracy. Shooting an arrow that is not stiff enough, or a group of arrows that vary in stiffness, will cause you to be less accurate. An under-spined arrow will veer right, while an arrow that is too stiff will favor slightly left.

All this said, how do you choose the proper spine of your hunting arrow? Well we have crunched the numbers for you. On nearly every wall of archery shops around the world is the famous Easton arrow selection chart. It’s the gold standard when it comes to picking the best hunting arrow. Follow the “variables” portion of the chart carefully, and most of all, provide accurate bow weight (measured!) and accurate draw length data. The main reason a hunter chooses the wrong arrow with the chart is because people often guess at these instead of measuring.

John DeMartini Wrote:
-------------------------------------------------------
> It doesn't matter which camp you align with, any
> rod that is built will have some perceived
> unfavorable characteristic. Over time the user
> overcomes these deficiencies by observing how the
> rod behaves and adjusting for these deficiencies.
>
> Accuracy is a function of the angler. The truth of
> this statement comes from real live events. I have
> been to many ICAST shows and there is always an
> area set aside for casting and rod handling. An
> area is set up with a rectangular pool 3 to 4
> inches deep and there are a number of fishing rods
> provided for demo, testing and occasional
> contests.
>
> It is amazing to watch the folks try their hand at
> casting different styles and builds. Mind you
> these folks have never seen or handled these rods
> before, but after some practice casts and
> adjustments, they handle them with remarkable
> precision. The obvious conclusion is that these
> folks have handled fishing rods before and learned
> to adapt to the rods characteristics and wound up
> working them accurately with little effort.
>
> Even if the rod is built perfectly, anglers have
> to adjust their handling of the rod depending on
> the lure and line used, worms require a different
> effort than a crank bait or top water, etc. plus a
> whole host of other variables some of which are
> wind,rain, temperature and on and on.
> There are hundreds of lures out there and I don't
> plan to build the perfect rod to handle each type
> of lure. I fish mostly from a canoe and bring two
> rods, one rod is strictly set up for worms and the
> other rod is used for any other lure imaginable
> and I use them both effectively.
>
> Any rod that is a pleasure to fish with, it's a
> winner.

"Accuracy is a function of the angler" was my point in answering the second question. In a scientific experiment setting where one could control all other variables, maybe a certain orientation might make a difference. But, in the real world there are simply too many variables.

Bottom line essentially is having an arsenal of combos that will all behave more similarly than not when put to use. All on axis or all on spine - but regardless we humans will adapt and modify our cast as we learn the rods behavior (as mentioned above).

Gary Loomis believes that building on the spine is the way to build a rod, and seems to have advocated for this for about 40 years. He claims it leads to more accurate casts with greater distance. I posted 2 video links on the first page of this thread.

But essentially, if the physics Gary claims truly applies, then the only thing that would seem to be remaining after a person compensates for either spine or straightest axis is potential increase in casting distance.

Gary explains it well in the shorter video, a 3 minute watch well worth it.

Building rods in MA, Building the community around the world

The spine is irrelevant to anything having do with casting, deadlifting, etc.

Casting distance has to do with the amount of weight being cast plus the input from the person casting. It is a two-pronged thing and has nothing to do with the spine effect.

The spine only has an effect in a spine finder or in your rod shop. On the water it goes out the window. 50 years of this mythical nonsense and nobody can provide any actual research, data or results to prove building on the spine creates a superior fishing rod. The only thing any research or data does show is that building on the spine results in a weaker rod that will fail under less load that if the rod had been built on the straightest/stiffest axis.

............



Edited 1 time(s). Last edit at 01/22/2023 09:18PM by Tom Kirkman.

Hey hey hey now....... an insurance salesman discovered rod spine and said it was so..... so it must be so!

Re: Spine or straightest axis?
Posted by: Tom Kirkman (Moderator)
Date: January 22, 2023 09:09PM

The spine is irrelevant to anything having do with casting, deadlifting, etc.

Casting distance has to do with the amount of weight being cast plus the input from the person casting. It is a two-pronged thing and has nothing to do with the spine effect.

The spine only has an effect in a spine finder or in your rod shop. On the water it goes out the window. 50 years of this mythical nonsense and nobody can provide any actual research, data or results to prove building on the spine creates a superior fishing rod. The only thing any research or data does show is that building on the spine results in a weaker rod that will fail under less load that if the rod had been built on the straightest/stiffest axis.


Both a bearing based spine finder and your preferred, or rather it seems insisted upon, method of finding the straightest or strongest axis are both simple, non-technical, inexact methods to approximate finding the "stable plane" of a graphite tube such as a fishing rod blank or golf shaft. To accurately determine that plane requires one to measure the oscillation of the shaft, typically by laser, and find what is commonly referred to as the "Flat Line Oscillation" or "Vertical Oscillation Plane, the strongest axis of an asymmetrical graphite tube. This measurement is quite simple in golf shafts and only takes seconds to undertake. More detailed versions of it have been patented under the name "SST Pure."

Bearing based spine finders or your preferred straightest axis measurement essentially determine the bow of a shaft, which typically will not correlate with the true Flat Line Oscillation or strongest axis, though sometimes it will, or will be close. Both these rod measuring methods are simple mechanical approximations with lots of margins for error.

Even with the exactitude of Flat Line Oscillation in finding the exact, irrefutable stable plane of a tube, there is continued debate as to its true benefit in terms of increased accuracy or performance in golf, though many golf shaft engineers will swear by it, and a vast number of PGA tour players have their shafts SST Pured, and have won nearly $2 billion in prize money with those pured shafts. SST Pure and other shaft designers contend they have data to prove the benefits.

The same technology could easily be applied to fishing rods, but there is not the audience or financial reward that exists in the golf domain. So we debate and rely on much more crude methods, neither of which we have sufficient data to point to a performance advantage.

One man's mythical nonsense is another's religion.

I have spined rods, built them based on their straightness, and just put them together with no regard to either. They all seem to cast fine and catch fish.

No axis of a rod blank is "stable" under load. Only guide placement can make a rod stable. This was the impetus for the spiral wrap all the way back in the early 1900's. It, and such contraptions as the "Bass Handler" handle in the 70's, were designed to combat the inherent instability of all casting rods, yes, even those built on the spine.

Over the years I have had many rod builders tell me that if you don't build a spinning rod on the spine, it will twist and torque until the guides have spun to the top. I'm still waiting to see that.

We have sufficient data to prove that rods built on the straightest (strongest) axis offer a performance advantage in terms of offering greater deadlift capability than rods built on the spine. We have data to prove that only guide orientation can eliminate rod twist under load. There is no data whatsoever to prove or even suggest that building a rod on the spine eliminates twisting under load or increases casting accuracy.


............

Tom: you state "Generally the spine and the straightest axis will be somewhere from about 90 to 179 degrees opposite each other."

Assuming you have a straight blank, the "straightest axis" is essentially eliminated from the equation, at least visually. That is, as you're looking down the barrel, rotating the blank along its long axis fails to highlight any deviation of the blank along that axis visually because it is straight. Let's make believe that we have one of those.

When put through one or more of the various techniques that one may prefer, the "spine" of the blank can be discovered which I agree wholeheartedly is in fact the weakest section along the long axis of the blank. As I have mentioned in another discussion, I very much misunderstood how to "properly use the spine" of a blank way back when, and once I did find it, I promptly rotated the blank ninety degrees to what was what I considered to be the strongest aspect of the blank. This is where I would apply my guides. I just logically (in my mind anyway) never thought that guides would preferably be aligned along the weakest aspect of a blank.

I just purchased what turns out to be one of those "make believe" blanks that happens to be pretty darn straight. With that, since there is no real cosmetic effect to deal with, does it make any sense to apply a set of guides along the weakest aspect of the blank as opposed to applying them on the strongest aspect of the blank?

I am not disagreeing, Tom. We are essentially talking about the same desired theoretical outcome. What you are calling the strongest axis is what some engineers call the stable plane, which really means the most stable or strongest plane (or axis) of a graphite tube. As we know, a graphite tube of course looks round but is actually asymmetrical, thus the rub.

BUT to truly and accurately determine that axis requires a better and more precise methodology than spining with sealed bearings or employing your straightest axis method. In reality these are noble but inaccurate mechanical attempts. Granted, with a little luck, either can fall within a few degrees of accuracy on a particular blank, but they are not precise, and often are far from it. And they are prone to user error.

The plane we both seek is best determined through the measurement most often called flat line oscillation. Flat line oscillation employs a simple laser depiction of the rod oscillating on its most stable or strongest axis. Attach a laser to the end of the tube, oscillate the tube, and orient the tube until the laser is moving up and down in a straight -- or flat -- line. If the laser is not moving in a straight line, but rather in an oblong or non-linear pattern, the rod or shaft is not oriented on its strongest plane or axis.

From theory to reality: orienting on the strongest or most stable plane is still not fully accepted in terms of its ability to deliver true performance or accuracy benefits, though it certainly seems to make total sense from a physics standpoint, and surely cannot detract from performance, whereas a theoretical case can be made against the opposite.

I may endeavor to create a laser device to measure a rod blank's oscillation and compare those results to both spining and straightest axis measurements and see the differences. This has been done with golf shafts for some time, and flat line oscillation is irrefutably more accurate and precise than spining. Sometimes the delta is quite significant.

To the benefit of us all, rod blanks and golf shafts are produced so much better today than in the past and to such tighter specs, that what we debate may be of no real practical use to the typical angler when building on a well made blank. But it is fun to experiment, try to find out, discuss and debate.

I have never had a rod break under load, which is not a concern of mine, nor is torque. I do not believe a rod would break or flip from torque under fishing conditions. It could break due to a design flaw, nick or an applied force greater than the rod's capacity.

Again, my focus is only on fly rods, and all are two and mostly four piece.

Thanks for all you do for rod building. I build and obsess over fly rods and golf clubs, but only for the fun and learnings of it. My fly fishing and fly casting handicap would be quite low. My golf handicap not so much.



Edited 1 time(s). Last edit at 01/23/2023 04:39PM by david taylor.

Just an example of how many threads there are on this topic.


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