I read the article and understand what it's saying, but I still have my reservations about any of this mattering unless, perhaps, you're building rods to catch huge salt water fish. But, again, I'm new and may soon learn I'm off my rocker. But, on my first build, I put the butt of the blank on our ceramic tile floor, put a bend in the upper third and rolled it. It snapped into a position that felt natural to the rod. I repeated the process probably 8 or 9 times. It actually flipped into two positions, but flipped into one of the positions more than double of the other so I went with that. And, I put the guides (casting rod) on the outside of that bend. So, is that the spine or not? All the videos and such say it is with the exception of Gary Loomis. He doesn't know if it's the spine or not. "I just know that's where the guides go" he said.

Also, I took some pics of my new rod build after I put the reel on it and rigged it with one of my homemade jigs. I had a hard time getting the rod positioned how I wanted it. Why? Because, the reel naturally wants to spin to the inside of the angle between the wall and rod. This begs the question, at least to me, how does the reel effect the spine and straight axis, etc... And, when we fish casting rods, we're forcing the rod/reel combination into a position it would otherwise not do on its own. This be why spinning rods seem to, at least to me, fish easier. I'm not talking about casting or controlling back lash. I mean how the rod feels in the hand. Spinning rods feel more natural to me. And, I'm ambidextrous so it's not a left right handle thing either. They just feel good to me. Baitcasters, not so much. Because, again, let go and see what the thing does.

Anyway, this is a very interesting topic, but I'm still not sure I buy into it mattering all that much. BUT, because I'm new, I'm going along with conventional wisdom when building my rods, despite what the analytical part of me says to do, at least for now.

Daryl Ferguson Wrote:
-------------------------------------------------------
> I read the article and understand what it's
> saying, but I still have my reservations about any
> of this mattering unless, perhaps, you're building
> rods to catch huge salt water fish. But, again,
> I'm new and may soon learn I'm off my rocker. But,
> on my first build, I put the butt of the blank on
> our ceramic tile floor, put a bend in the upper
> third and rolled it. It snapped into a position
> that felt natural to the rod. I repeated the
> process probably 8 or 9 times. It actually flipped
> into two positions, but flipped into one of the
> positions more than double of the other so I went
> with that. And, I put the guides (casting rod) on
> the outside of that bend. So, is that the spine or
> not? All the videos and such say it is with the
> exception of Gary Loomis. He doesn't know if it's
> the spine or not. "I just know that's where the
> guides go" he said.
>
> Also, I took some pics of my new rod build after I
> put the reel on it and rigged it with one of my
> homemade jigs. I had a hard time getting the rod
> positioned how I wanted it. Why? Because, the reel
> naturally wants to spin to the inside of the angle
> between the wall and rod. This begs the question,
> at least to me, how does the reel effect the spine
> and straight axis, etc... And, when we fish
> casting rods, we're forcing the rod/reel
> combination into a position it would otherwise not
> do on its own. This be why spinning rods seem to,
> at least to me, fish easier. I'm not talking about
> casting or controlling back lash. I mean how the
> rod feels in the hand. Spinning rods feel more
> natural to me. And, I'm ambidextrous so it's not a
> left right handle thing either. They just feel
> good to me. Baitcasters, not so much. Because,
> again, let go and see what the thing does.
>
> Anyway, this is a very interesting topic, but I'm
> still not sure I buy into it mattering all that
> much. BUT, because I'm new, I'm going along with
> conventional wisdom when building my rods, despite
> what the analytical part of me says to do, at
> least for now.

Yes the outside of that stressed curve is the spine or weakest axis. But your "test" does not approximate a real world fishing situation. No fish will ever jump from the water, put a fin on your rod tip and pull down on it. The fish will pull on the line, which runs through guides which are lever arms, and easily overcome any spine effect.

As far as the strongest axis not helping you unless you are up against huge saltwater fish.... suppose you are fishing an ultra-light rod? Why would you give up whatever maximum power the rod has? Why would you want the rod to fail at a load that is less than it could have withstood if you put it's strongest axis in play?

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

Golf shafts and fishing rod shafts have what is known as a "spine" due to the way they are produced, and one may think of it as they may.

Here is an excellent video on the subject in regard to golf shafts:

[www.youtube.com]

The golf shaft or fishing blank is not perfectly round and, thus, will have a stable plane, in golf called its FLO, for flat line oscillation, and can be determined by oscillating the shaft with a weighted laser pointer on the end.

It is not practical to to use this technology on rod blanks as the tip section is so narrow and light. Thus people use a device known as a spine finder, which is a tube or cartridge with two encased bearings. One spins the rod and finds the location where it flips and settles, which is the spine. Finding the spine is more difficult on the lower two pieces, especially the butt piece, of 4 piece rods. This can be done also by twisting the rod while holding it on a solid surface, like a counter top. Plenty of videos out there.

We can argue this until the cows come home, just as FLO is argued in golf. Personally I use my $15 DIY spine finder to align the fly rods I build. I have four blanks I am building in the weeks ahead, so I made a spine finder rather than using the table top method.



Edited 3 time(s). Last edit at 01/21/2023 06:31PM by david taylor.

You cannot compare golf shafts to fishing rods in terms of what they do in actual use. Bending or flexing a rod by hand or via a mechanical device and finding the spine effect in no way replicates a real world fishing situation. Fish don't jump out of the water and pull on your rod tip with a fin. They pull on the rod via a line that is running through a series of guides bound to the rod blank. In that instant, any spine effect goes out the window and the lever arm effect of the guides takes over.

All rods with guides on top are inherently unstable. All rods with guides placed along the bottom are inherently stable. And these statements remain true regardless of spine orientation.

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

Peter,
Over the years I have checked the spin on many many many rod blanks.

Some of the blanks have really really pronounced spines.

But the spin, light, medium or strong has never inhibited me from building on any blank because of the spine.

But, as long as the spine is not severely different from any observed natural bend in the rod, I still generally don't worry about the spine and simply build on the straightest axis.

Best wishes

Tom Kirkman Wrote:
-------------------------------------------------------
> Daryl Ferguson Wrote:
> --------------------------------------------------
> -----
> > I read the article and understand what it's
> > saying, but I still have my reservations about
> any
> > of this mattering unless, perhaps, you're
> building
> > rods to catch huge salt water fish. But, again,
> > I'm new and may soon learn I'm off my rocker.
> But,
> > on my first build, I put the butt of the blank
> on
> > our ceramic tile floor, put a bend in the upper
> > third and rolled it. It snapped into a position
> > that felt natural to the rod. I repeated the
> > process probably 8 or 9 times. It actually
> flipped
> > into two positions, but flipped into one of the
> > positions more than double of the other so I
> went
> > with that. And, I put the guides (casting rod)
> on
> > the outside of that bend. So, is that the spine
> or
> > not? All the videos and such say it is with the
> > exception of Gary Loomis. He doesn't know if
> it's
> > the spine or not. "I just know that's where the
> > guides go" he said.
> >
> > Also, I took some pics of my new rod build after
> I
> > put the reel on it and rigged it with one of my
> > homemade jigs. I had a hard time getting the
> rod
> > positioned how I wanted it. Why? Because, the
> reel
> > naturally wants to spin to the inside of the
> angle
> > between the wall and rod. This begs the
> question,
> > at least to me, how does the reel effect the
> spine
> > and straight axis, etc... And, when we fish
> > casting rods, we're forcing the rod/reel
> > combination into a position it would otherwise
> not
> > do on its own. This be why spinning rods seem
> to,
> > at least to me, fish easier. I'm not talking
> about
> > casting or controlling back lash. I mean how
> the
> > rod feels in the hand. Spinning rods feel more
> > natural to me. And, I'm ambidextrous so it's not
> a
> > left right handle thing either. They just feel
> > good to me. Baitcasters, not so much. Because,
> > again, let go and see what the thing does.
> >
> > Anyway, this is a very interesting topic, but
> I'm
> > still not sure I buy into it mattering all that
> > much. BUT, because I'm new, I'm going along
> with
> > conventional wisdom when building my rods,
> despite
> > what the analytical part of me says to do, at
> > least for now.
>
> Yes the outside of that stressed curve is the
> spine or weakest axis. But your "test" does not
> approximate a real world fishing situation. No
> fish will ever jump from the water, put a fin on
> your rod tip and pull down on it. The fish will
> pull on the line, which runs through guides which
> are lever arms, and easily overcome any spine
> effect.
>
> As far as the strongest axis not helping you
> unless you are up against huge saltwater fish....
> suppose you are fishing an ultra-light rod? Why
> would you give up whatever maximum power the rod
> has? Why would you want the rod to fail at a load
> that is less than it could have withstood if you
> put it's strongest axis in play?
>
> ................

Yes, I suppose you're right. I'm thinking through it in terms of how I fish and the type of rods, etc... I use currently, not necessarily what I may or may not do in the future. Like you say, if I'm going to go through the trouble of building it, I may as well take advantage and make it as strong as I can regardless of how I'm fishing it. With that said, I'm hoping you, or someone, can clear up a bit of confusion I have.

1. So that test I do (that I learned from Mudhole, Flex Coat and others does indicate the spine of a blank? If so, how is that not also the "natural bend" since the blank is jumping (lack of a better term) into that position on its own?

2. If I put a rod blank in a stand toward the butt and another about a foot forward toward the tip, roll the blank until I see the tip take a pronounced downward turn, is the top of the blank (with the tip facing down) the straightest axis? I'm just confused on how to find the straightest axis.

Thanks!

The natural curve is visible. The "stressed" curve would be where a pressured blank jumps away from the strongest axis and then settles into the weakest axis. That curve (weakest axis) is usually referred to as the "effective spine." It is not a physical thing, of course, just an effect created by various manufacturing anomalies.

The easiest way to find the straightest axis is to simply sight down the blank. If you have a rod wrapper or lathe, chuck the butt and put a rod support maybe a foot beyond that. Put something out near the tip so you can relate to it as you slowly turn the blank. Once you determine the straightest axis, mark it and then flex the blank against that axis. 99% of the time you'll be flexing against the rod's strongest axis. Remember, this would be butt and tip up, belly down, in a fishing situation.

Do whatever you want. There is no right or wrong way. But if you are attempting to create a stable rod by a particular spine orientation - you can't do it. Guide orientation dictates whether or a not a rod will be stable under load.

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

Tom Kirkman Wrote:
-------------------------------------------------------
> The natural curve is visible. The "stressed" curve
> would be where a pressured blank jumps away from
> the strongest axis and then settles into the
> weakest axis. That curve (weakest axis) is usually
> referred to as the "effective spine." It is not a
> physical thing, of course, just an effect created
> by various manufacturing anomalies.
>
> The easiest way to find the straightest axis is to
> simply sight down the blank. If you have a rod
> wrapper or lathe, chuck the butt and put a rod
> support maybe a foot beyond that. Put something
> out near the tip so you can relate to it as you
> slowly turn the blank. Once you determine the
> straightest axis, mark it and then flex the blank
> against that axis. 99% of the time you'll be
> flexing against the rod's strongest axis.
> Remember, this would be butt and tip up, belly
> down, in a fishing situation.
>
> Do whatever you want. There is no right or wrong
> way. But if you are attempting to create a stable
> rod by a particular spine orientation - you can't
> do it. Guide orientation dictates whether or a not
> a rod will be stable under load.
>
> ............

The goal of using the straightest axis is to have the guides oriented in a way to effectively have the strongest part of the blank take the brunt of the load, right? Or, is just an aesthetics thing?

Both!
Norm

Again, I’m new to all of this. But wouldn’t when rolling the rod to find the spine, and when it actually jumps to the stop point, wouldn’t this in theory be the weakest orientation? Reason my thinking is behind this, is because I can feel the amount of resistance change when the flop occurs. I do agree that position is where the rod would want to bend the most easily.

Jonathan Collins Wrote:
-------------------------------------------------------
> Again, I’m new to all of this. But wouldn’t
> when rolling the rod to find the spine, and when
> it actually jumps to the stop point, wouldn’t
> this in theory be the weakest orientation? Reason
> my thinking is behind this, is because I can feel
> the amount of resistance change when the flop
> occurs. I do agree that position is where the rod
> would want to bend the most easily.


Yes, the inside of that curve is the weakest. From what I'm understanding, however, is that doesn't mean the outside of that curve is the strongest. If I'm understanding correctly, that's rarely the case. More often than not, the strongest is the straightest axis which can be 90 degrees or more away from the weakest. The big argument for finding the spine, or effective spine as they're calling it in here, according to the likes of Mudhole, Gary Loomis and Flex Coat is that finding the spine ensures that the rod doesn't try to spin, or torque, under load. It sounds like some of the guys in here don't find that to be true, however. Hopefully, I explained it correctly. I'm new too.

I suggest you read the article Tom posted earlier in the thread. It explains it better than I probably am and they give test results after putting the rods under load.

Spine orientation will not stop a rod from twisting or torquing. This is the great fallacy of using spine finders, rolling a blank by hand, etc. - None of them approximate what happens in actual use where you have a fish pulling on the rod via a line which is passing through guides bound to the rod shaft. Once you do that, the lever arm effect of the guides takes over and easily overcomes any spine effect.

This is the main reason that the spiral wrap came into being - it created an inherently stable casting rod, something that cannot not be accomplished by spine orientation.


...........

Tom, I know I'm probably driving you nuts by now, but one last question just so I am 100% clear on this. You stated:

Once you determine the straightest axis, mark it and then flex the blank against that axis. 99% of the time you'll be flexing against the rod's strongest axis. Remember, this would be butt and tip up, belly down, in a fishing situation."

In reading that I'm visualizing a smiley face when I flex it. So, if I chose to orient my guides via this method, I would put my guides on the side that has the belly down (smiley face), or the belly up (as in a frown). Belly down seems like that would be the stronger of the two. Again, my apologies for all the "NOOB" questions.

Convex side down. If you're building a conventionally wrapped casting rod ....... guides on the concave side of the blank.

If a spinning rod ....... guides on the convex side of the blank.

Use the weight of the guides to help the blank appear straight when sighting down it

Re: Spine or straightest axis?
Posted by: Tom Kirkman (Moderator)
Date: January 21, 2023 07:41AM

"You cannot compare golf shafts to fishing rods in terms of what they do in actual use. Bending or flexing a rod by hand or via a mechanical device and finding the spine effect in no way replicates a real world fishing situation."

I am not comparing them in use, but in how as tubes, they are produced, and that in that production process there are certain stronger or weaker points of orientation of the blank, which is not a perfectly circular tube. Both a rod and golf shaft are used as a lever to perform a certain task. In casting, or in hitting a golf ball, many folks believe there is an advantage to aligning the rod/shaft on a particular plane or axis relative to what has been called its spine, and that the casting of a rod or striking of a golf ball will be more precise or consistent due to such alignment.

I am in no way stating, implying or contending such orientation is of any benefit in fighting a fish. Further, the torque of a graphite rod or shaft is an entirely different matter, as that is the measure of how much a tube will twist under a certain amount of force. I am not familiar with the torque of a typical fly rod, but in golf a graphite shaft will typically have a torque of 2 - 4.5 degrees, a steel shaft less.

Daryl Ferguson Wrote:
-------------------------------------------------------
> Tom, I know I'm probably driving you nuts by now,
> but one last question just so I am 100% clear on
> this. You stated:
>
> Once you determine the straightest axis, mark it
> and then flex the blank against that axis. 99% of
> the time you'll be flexing against the rod's
> strongest axis. Remember, this would be butt and
> tip up, belly down, in a fishing situation."
>
> In reading that I'm visualizing a smiley face when
> I flex it. So, if I chose to orient my guides via
> this method, I would put my guides on the side
> that has the belly down (smiley face), or the
> belly up (as in a frown). Belly down seems like
> that would be the stronger of the two. Again, my
> apologies for all the "NOOB" questions.


Visualize the rod, either spinning or casting, insofar as how it is oriented to the water. Butt and tip up, belly down. Put the guides where they would go for spinning or casting as they need to be. Either way, the blank orientation is the main thing to visualize. Yes, like a smile. And this is the same for either spinning or casting.

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

David,

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

..........

Got it! Thank you Tom, and David Baylor.

Picture is showing the slight offset of stripper to minimize rubbing

Not sure you can compare any torque caused by the spine of a fishing rod and the torque caused by the spine of a golf club shaft. The accuracy of a cast not only depends on the position of the rod tip at the time the line is released, but it also depends on the position the rod tip stays during the entire duration of the cast.

The same is not true of a golf club striking a ball, Once the ball has left the face of the club, it can't be directed by which way the club is pointing afterward.