I just saw a video, [m.youtube.com] , where a fellow explained rod spine as where the layers of graphite (young fellow, never heard of fiberglass) overlap as the material is rolled on the mandrel. Where the end of the material acts with the beginning of the material to create a stronger side, thus forming the spine. He further explains how the spine must be placed as the rod bends so the rod doesn’t twist under load in the angler’s hands. So far so good, this is how I’ve always placed the spine. However, I’ve recently seen discussions here where rod builders orient the blank according to the straightness of the blank, particularly on multi section fly rods.
I’m now slightly confused, not an unusual state of mind for me, on how to orient spine for what blanks. Does anyone care to try to educate me?

The video you watched is 100% wrong, the material doesn't form a seam like that, it spirals. SO unlearn anything you saw in that video.

Wait...you mean... something I saw on the internet is wrong?!
O, woe is me.

Seriously, you’re right when I slow down and think about it.

I have not seen the video, but as far as spine, the physics of it are a simple comparison of 2 ways of doing it. One can always step out of these 2 ways and go sideways, but why?

If we go with using the spine of a rod, or the one side the rod wants to bend to more easily than any other way...

Then were are left with 2 choices. Soft spot up or down.

I choose to put the soft spot up because when I cast a rod I want the rod to seek its cast loading bend into that soft spot so I can count on it rebounding out of that soft spot during the cast in a straight line motion which I believe gives me the most accurate casting ability.

If I reverse this and put the soft spot down, then when I go into my back swing to load up the rod for the cast, due to the fact the rod does not want to bend straight into my back swing naturally, but is resisting loading up in my back swing, the rod will want to skew off to one side or the other and I believe this lends itself to making accurate casting much more difficult.

Another reason I put the soft spot up is because when the rod is loaded with a fish, the rod has it strongest load carrying ability opposite the soft spot, so I have more rod resistance to the fish which is to my advantage. I am not concerned with the rod wanting to torque over because as with a spinning rod, all guides are underneath and the rod can not overcome the leverage action of those guides and is not a problem.

Now on my baitcast rods, I now use only spiral wrapped rods with short micro guides, and even with those I have never ever had a problem with a rod overcoming the leverage ability of micro guides. So honestly this claim you mention "He further explains how the spine must be placed as the rod bends so the rod doesn’t twist under load in the angler’s hands" does not exist in any measurable form for me to even be of a consideration. But if I were to use rods with guides on top, then maybe when combined with the leveraging effect of the guides on top, the rod position might come into a position of greater consideration, but I as yet have not reached that point yet. Not an issues.

I am more concerned with casting accuracy than with any torquing issues with a fish on the line. And I can not speak on multi section rods because I don't use any. I am of the belief that performance directly relates to single rods. When you start cutting up rods, performance begins to go downhill. I have yet to find any 2 section rod- or more- that can compare with the action of single rods.



Edited 1 time(s). Last edit at 01/09/2021 08:18AM by Kent Griffith.

Guy

There is just enough truth in the video you watched to be wrong. I know that sounds strange but hang with me. Yes, for many if not most blanks or blank sections there is a weak or soft side and a hard or strong side ("the spine"). This is true for bamboo, carbon fiber, composites, etc. and there can be more than one spine. Where things go sideways (so to speak) is assuming the spine has a significant influence on a rod's casting and fish fighting properties. I build very few spinning or bait casting rods so I'll make no claims for them. But for fly rods 1 through 12 weight over more than 20 years I assure you spine is seriously over rated



Edited 1 time(s). Last edit at 01/09/2021 09:57AM by Donald La Mar.

If you want to think of it as an effect created by a number of manufacturing anomalies, rather than a physical thing, you'll have an easier time understanding it. And the stiffest and softest axii are not 180 degrees apart.

Rod twist is caused by the lever arm effect of the guides, not "spine."

If you want the maximum power and deadlift capability of the blank to be in play when fighting a fish, read this: [www.rodbuilding.org]

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

Thank you for the replies, this has been really interesting.
To be sure I know the reference, if I hold a bare blank by the tip, support it with my other hand a ways down the blank, and lift it into the air, the blank will rotate to a certain orientation. Is this the strong side or the soft side that is facing up?

I just had a scary though..i,ve been fishing with an unspined tenkara rod..it could have blown up in my face..whew!...i must take each section and find and mark the location of the spine so that i can assemble it properly or suffer the consequences..not today, maybe tomorrow..lol.

ben belote Wrote:
-------------------------------------------------------
> I just had a scary though..i,ve been fishing with
> an unspined tenkara rod..it could have blown up in
> my face..whew!...i must take each section and
> find and mark the location of the spine so that i
> can assemble it properly or suffer the
> consequences..not today, maybe tomorrow..lol.


The only interesting thing about spine is that it creates a lot of drama, if you like drama..and it seems that many rod builders do..

The spine of a blank and life in general have always confused me. So...if someone who has built on a glass, 4 piece fly blank can tell me...does fiberglass have a spine and is there any tips on placing guides other than in a straight line? I have read (i believe it was on here) that glass has no spine. Thanks.

Because the material is spiral wrapped the wall thickness at any location may not be homogeneous compared to a point 180 degrees away, this non-uniformity is the reason the blank responds stiffer or softer depending on which axis it is flexed.

If you look up back posts there are endless discussions about the spine and where the guides should go There are valid pro and cons but the final decision ultimately rests with the builder.

Each blank is different so I check the spine and the position of the straight axis and decide the best location for the guides Most of the time I wind up placing the guides along the straightest axis.

To set your mind at ease, you can before you set the reel seat, set up the guides with masking tape, one along the soft spine, one along the stiff spine and one along the straight axis.and decide which is the best look and feel for that blank. It is extra work but the results will be worth the effort.

Have fun

All blanks have a spine. It is just part of the manufacturing process. Most here pay no attention to it at all. Not sure why you wouldn't want your guides in a straight line. Other than a spiral wrap that is.

Russ in Hollywood, FL.

Todd,
A Glass blank certainly has a spine.

And - since CTS blanks are remarkedly straight - I always build according to the spine - as do all my customers.
CTS offers to mark blanks with spine/alignment marks - and most avail themselves of these marks.
Herb
U.S.CTS Rep



Edited 1 time(s). Last edit at 01/09/2021 12:25PM by Herb Ladenheim.

In the words of Gary Loomis... "I don't know where the spine but what I do know is where to put the guides"

[www.youtube.com]

What I do is find the "spine" using the rotational method. Typically I fine that there are 2 directions the rod gravitates towards. Then I put the blank on the lathe and rotate it until the tip is curving upwards at its highest point for casting or downward at the lowest point for spinning. The guides placed on the 0 axis. Almost alway it is in line with the two "spines" I marked earlier and this is the straightest axis to build on.

Gary makes the point that the most important part is that the guides placed in this way help dampen the oscillation after a cast. Now I wonder if he actually took a high speed camera to see if it works and if so, how much it helps.

Build the way you wish. I always build on the straightest axis with the tip pointing up. I dislike having the tip pointing off to one side or the other. Never had problems with accuracy, which depends on me. Reel torque is dependent on guide placement, top (yes) vs bottom (no). Absolutely your choice.
Norm

I always build with the straightest axis with the tip pointing down.

The reason that I build with the tip pointing down is for myself - it looks better.

Take care

I find it easier to build rods on the anti-spine rather than the spine, even though the anti-spine is more than twice as hard to find than the spine.



Edited 1 time(s). Last edit at 01/09/2021 04:51PM by Phil Ewanicki.

Phil, is the antispine anything like antimatter which is also hard to find..lol.

I posted something a few weeks ago that got this very same discussion started. I now know that "get out the popcorn and enjoy the fun" is a very appropriate response on the subject.. I have read everything I can find on the subject. I am also a psychologist by trade. I have come to the conclusion that most of the opinions are based on more emotion than science. I have decided that it probably is not going to be noticeable to me how I decide to build it, but it doesn't seem like it could hurt to build on the spine Of course I am really a novice at this, so I may not even be correct on where I think the spine is!

Well let old Gary Loomis himself explain it! Here is a short youtube video where he explains it- and for the record, what I said above about where the soft side should be is exactly how Gary Loomis says it should be. So I guess I got it from him! Or, maybe, nah, I got it from him and I'll leave it there...

[youtu.be]

Gary makes it clear, soft side up, baitcast rod guides go on top of the spined bend, and if spinning they go on the bottom. Could not be more clear from the legend himself. Now if we could all agree on it is another story!

I also enjoyed hearing the man himself talk about how this spine is key to a straight loading rod for casting and how it releases straight based on the spine translating into greater casting accuracy. I have also noticed this same thing and today include it in every rod I make. Whether or not I learned it this way from Gary Loomis is beside the point, I am just glad to hear and learn what I do today is Loomis approved. I've been collecting his rods for many years now going back to LCI. Some of my favorites. Just picked up another Loomis this past week to add to the collection.



Edited 2 time(s). Last edit at 01/09/2021 06:39PM by Kent Griffith.