I have a 10' 4 pc Sage blank that I'm having a problem understanding the spine in the 30" tip section. I have a traditional double bearing spine finder that I use to locate spines rather easily, however it seems my tip section has two spines 180 degrees apart. I've attached my tip top inline with what I feel is the most predominate spine. I usually start with the equal angle/increasing angle process to get an idea of how many guides I need and use this info in conjuction with the static test.

In the past when I've assembled the blank sections and stretched a string between the tip and butt to bring the upper section to a 90 degree bend, the blank always bends with the spine situated on the outside of the curve - and my tip top position stays square and inline to that spine position. However, on this blank the tip top wants to rotate or relax to a position in between the two spines! I can rotate the tip top and it will jump to either of the 2 soft spots in between the 2 spines.

I assume I should ignore this phenomenom and keep the tip top inline with what I think is the most predominate spine . . . ? Thanks.

Tim, your problem is quite common. Keep in mind that most of the multi piece rods are built as three or four rods. As a result each section may have a different kind or spine. The pattern, layup, tacking technique and rolling procedure all effect the way the spine will feel and act. The technique you used will give a good place to start. The difference in the types of spines in the sections may result in some odd types of bends when the rod is loaded,as in casting.

A good way to check your spining results is to flex the rod in a spining position and then tape the guides on the out side of the curve. Next clamp two boards, broom handles or similar objects about 18 inches apart on a door or any object that will allow you to place the butt of the rod between them and flex it. Place the butt on the side toward the flex and use the top board as a fulcurm. This will hold the rod when you load it in a casting position. Now tie a line to the butt of the rod and run it through the guides extending it about 10 feet if possible. Have some one place the rod between the supports with the guides facing to the front or top of the rod and hold it as you pull on the line. If every thing is aligned the guides will lock on the top or the rod and it will be difficult to turn the rod. Flex the rod through the full bend that would occur during a cast. If the guides turn or torque to one side or the other, adjust the sections, retape the guides and repeat the flexing test. It may take several adjustments to achieve the lock-in you are looking for. If the rod will lock-in and remain in one plane during the entire flex, it will track perfectly straight during the cast. Even though we spine a rod and then place the guides where we think they should be, many of them will twist or torque during the flex of the cast.

I've heard this discussed a lot but I don't think twisting on the cast affects anything, certainly not casting accuracy. The rod is twisting around the same center axis so moving the line to the top, bottom, or one side or the other makes no difference. You'd never be moving it more than about 1/8th of an inch.

I have come to believe that having the blanks natural bend off to one side tends to make the lure or line 'sweep' during the cast and can affect accuracy. As much as I hate to say it, but I believe that the factories have been doing this right all along. Put the guides on the straightest axis you can find and disregard the spine.

What got me to thinking on this was the interview with Press Powell in a past issue of Rodmaker. His comments on rod spine and casting accuracy just seemed to make a lot of sense.

Interesting point. When I was testing things on a casting machine I was not able to get a blank to throw off center no matter where I oriented the effective spine. I'm also convinced spine has nothing to do with casting accuracy.

Badly warped or curved or crooked blanks are altogether different, however. If you put the crook or warp so that it is 90 degrees to the casting plane, you will find your lure or line to go off target. The greater the crook or warp, the farther off the intended target you'll be.

Now add to that the fact that if you position the spine on most blanks either straight up or straight down, any such crook or warp will almost always end up off to one side or the other (90 degrees to effective spine). Such is life.

In a perfect world, blanks would have no spine effect whatsoever. In a not so perfect world, the best you can really hope for is a spine effect that creates the situation you have where they are exactly 180 degrees apart.

Now let me throw in one other thing - when you attempt to find the spine of a multi-piece rod in a spine finder of the sort you mention, you will not get the true effective spine location. A large percentage of the short blank section will be inside the spine finder and somewhat prevented from factoring into the end result. Spine finders of this type are great on one piece or longer multi-piece sections, but they leave a bit to be desired on short rod sections.

I would perform the task the way Don has mentioned, or trust your string-flex on the first go around. Assemble the sections and test over the whole length. If the rod's overall spine falls close to what you have marked on the tip, you're okay. If it goes way off, then you'll need to back up and try again.

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You see this on many blanks. On some blanks the two spines may not be 180* apart but something less, ie. 160*. I have found blanks that don't have a spine too, but they are rare. Most often rods will have a prominent spine and one a less prominent.

Select the most prominent of the spines and build using that reference.

Lou

William,
I thought that I was the only heretic when it came to the conventional beliefs about the spine. I think that I have found a fellow heretic. Actually Tom may be as well.
I wish that the blank manufacturers would look closely at what a couple of the golf club manufacturers are doing. They are building graphite golf club shafts with no detectable spines.

Being shorter and larger in diameter, golf club shafts are somewhat easier to construct. One of the contributing factors to the spine effect is any inherent warp or curve to the shaft. The longer lengths and smaller diameters of most rod blanks make it almost impossible to have a perfectly straight shaft, so building a "spine-less" rod blank is pretty tough to do.

One rod builder took a different, "if you can't beat them join them," approach. About 15 years ago a fellow named Nicholas Whipp created mandrels with two opposing flats milled on the surface. The flats were hand filled with graphite strips and then the assembly was rolled as usual. This created a blank that while round on the outside, had two slightly thicker areas, 180 degrees apart, on the inside. The result was a blank that had a very pronounced spine effect, but always on the same plane and the same whether you were working with the entire blank length or just a portion.


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Tom,
Yes, that would make sense if you thought that the spine was a desirerable characteristic of a blank. I do not. I do agree that it is probably a good deal more difficult to eliminate a spine completely in a rod blank but I think that should be the goal. In my judgement the spine is an inherent flaw in a blank and less would be better. This may not be practical or achieveable with todays technology or manufacturing processes but I think a perfect blank would be perfectly straight and have no detectable spine.

I certainly agree. I think Nicholas just decided that if you couldn't eliminate the spine effect then you might as well create a very strong one and be able to control where it would be.

It's a shame that rod blanks can't extruded - this would allow for perfect taper and wall thickness around the entire circumference of the structure. But, those materials that are extrudeable have a far lower modulus of elasticity than even the lowest modulus graphite. Even the stiffest plastics and composites would make very poor fishing rods compared to what we've become accustomed to.

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Edited 1 time(s). Last edit at 12/20/2004 03:21PM by Tom Kirkman.