I just read an old post by Tom Kirkman and some lights went on in my head. "The spline isn't a physical thing, but an effect," he explained. I'm a bit slow about understanding that, and for some reason, re-reading that post I finally made a connection.
But I do have a question: As you hold the rod in your hands in a pronounced curve and roll the blank, it usually jumps to what feels like a flat spot. I then mark the inside of the curved blank with masking tape and place my fly rod guides on that inside of the curve. Am I understanding this correctly?

IMO, Yes. Softer spine
toward the fish gives less
tendency to twist. IMO, -Cliff Hall.
Barring some over-bearing curvature.

If you want to bother with the spine, that would be the way to go. Personally, In the real world, I don't think that spine orientation has enough (if any) effect on a rod to bother with it. Most blanks have a natural curve to it and I always build to the straightest axis with the belly of the curve on the bottom of the rod. I think that a tip pointing off to the left or right would have far more effect that the spine

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!!

Bruce

I think you will get many differing opinions on this...my prediction is the 3 most popular will be..

Guides on inside curve of spine

Guides on outside curve of spine

Don't care about spine...guides aligned to the natural curve of the blank to make the rod as straight as possible

I think all are good options.....

The outside of that curve is the reference point generally referred to as the Effective Spine. Doesn't really matter where you mark it as long as you know what position it references.

But, your guides don't have to go in any particular place relative to the spine. They can go on it, opposite it, or some manner off from it and all will be correct positions.

..........

Putting the guides on the inside of the curve seems natural, and is the way I have always done it. However, there is an article in RM magazine advocating just the opposite (i.e. putting the guides on the outside of the curve) for rods whose principle activity is casting (i.e. a fly rod), presumably using the flex to propel your fly line further on the forward cast. At least theoretically, this makes sense to me. I plan to do it this way on my next several builds and see if it make any noticeable difference...I suspect it does not. As stated above, this is a contentious subject.

This sounds like something Rich Forhan would write. Seriously, you won't see much difference in casting distance or accuracy one way or the other. By all means try it and satisfy your own curiousity.

...........

Tom, you are correct--it was Forhan...I couldn't remember the author's name.

I do things in a stupid way - but I like the way the rod handles when fighting a fish. I mark the inside curve of the bent section which is opposite of some sort of "ghost spine". Then I find the straightest axis of the "drooped down" side of the section. A lot of times these two marks are 180 degrees apart. But then I assemble the sections, aligning the common droop down marks, add a tip top but no glue so it spins freely, stretch a string from the top to an opened paper clip stuck in the butt end, tighten the string until there is a 90 degree bend and let the blank "roll" until it finds a stable position. I may twist a few sections to see if there's any change and once I find a positon the blank likes and seems the most pronounced, I mark the inside of that "new curve" and place my guides on it. I told you it was stupid!

No more stupid than any other way of doing it. If you like the way it works and feels then it's fine. If it was as important as some believe, there'd be one heck of a lot of rods that just don't work or exploded every time they're loaded. As we know, this isn't the case.

You have to remember that spine orientation has little to nothing to do with rod twist and if it's rod twist that damages blanks (and all can certainly withstand some amount of torsion) then spine falls completely out of the picture.

Unfortunately there are a lot of myths concerning rod spine and they die hard. Thankfully the past decade or so has seen many of them disproved.


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

Another thing that people don't stop to think about is that if you place the spine to supposedly aid in casting you have to remember that you cannot possibly cast in a perfect plane each time. Chances are that the spine you so carefully placed never even ends up being in the casting plane under actual use in casting.

I hate to see new builders worry over it so much. IMO there are many things that are much more important in terms of what makes a true difference you can feel in a custom rod. I'd say weight and how much you can limit or reduce it is numero uno. Balance is a close second. Handle size and shape are third with guide position and placement tied there also. Overall attention to detail and neatness is a given. If I were rating the things I thought were important on a rod I was fishing I'd have to put spine way down the list.

You hit it pretty good, Ken!

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!!

You guys that deal with that many blanks which are not straight? I rather worry about buying straight blanks than aligning guides on the straightest plane. I agree that the spine doesn't seem to make that much of a difference...but I LOVe the way a blank feels which was constructed with spines 180 apart and they lock in. Mos to fthe new Lamiglas graphites are made like this, I believe thanks to Don Morton.

Bass fishermen make casts from all sorts of positions and angles. You would never be able to position the spine in the casting "plane" as there isn't any single casting plane that these guys use!

I always thought it odd that we would take a blank and bend and push on it and then put the guides in a certain place. When you go fishing the only thing the rod feels is the weight on the line through the guides. All that hand flexing stuff is out the window. It never happens again.

In surfcasting, fly fishing, boat fishing...seemingly anything except Bass fishing - the rod usually gets casted from the same angle, you set the hook the same way, and reel in the fish the same way. So you would be able to position the guides in the casting plane...it just doesn't make that much of a difference. imo.

A spline is only a mouse click away when using Autocad -

A spine is what I am missing when dealing with my wife of 40 years -

Both are what rodbuilders seem to wonder about -

I really wish I had the only one of the above that was important to me!

I sell custom rods from my retail fishing outlet and we build them on the spine for one reason, I will garentee you that when the customer leaves the store with his new rod and proudly shows it off to his friends, some "EXPERT" will disapoint him by telling him his new rod is no good as it is built off the spine. Cutom rod builders here have been pushing the spine thing here for leverage to sell their product for far too long to change now, so we go with it. Personally I like heavy fly rods built on the spine as I find they have a tendency to twist in your hand on long casts.
Regards Paul.

It is true that no fish is going to jump out of the water, grab your rod with a fin, and flex it. What happens to a rod when it is loaded in an actual fishing situation is something that is not approximated by hand flexing/spining it. Two entirely different things. This is why if your goal is to prevent rod twist, you'd better look into spiral wrapping.

But I can see Paul's point from his position as a businessman. What he is doing is probably wise and it won't hurt the rod one bit. A satisfied customer is certainly important for repeat business.


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

I spined many rods over the years locating the spine where I had been taught that it had to go. Then I saw the light and moved on. I have been building on the straightest axis for several years now and believe the rods just feel better and cast straighter. No breakage problems but I really don't have any twist since nearly all my casting rods are built spiral style. Forget the spine and set yourself free to focus on the things that really make a great performing custom rod.

Ok, let me get this clear guys......

I've been 'spining' for every blank and you are saying that the spines really do not matter at all? Rather one should build it on the straightest axis?

I thought one of the 'advantage' custom makers could offer over factory assembled rods (even the high end GLX) is that the custom builder spins the blanks. Is there pretty good conscensus that this never really mattered?

Mo