A lot of interesting information for sure. I have been constructing my own spiral wrap rods for years and in practice I keep changing with each new rod done in a spiral wrap.
I read all these formula's people use which do work, but not all rods are the same and one formula may not be ideal for every rod.
On my latest spiral wrap I just finished today, I did something a little bit different because the rod told me to make the change on the 90 degree guide. I put the rod under load and watched the spiral transition change because of a slight curve in the rod shifted the angle the line flowed through the guide under load, so to straighten this out I had to readjust the 90 degree guide to closer to 100 degrees.
I have build spiral wraps in several different ways with the first guide at 0 degrees, the next at 90 and third at 180. And I have even used up to 4 guides in the spiral wrap, but today I only use 3. (And for the record as mentioned in this thread, I am not one of those people who would just use two guides and let the line rub on the rod. Not me, but to each their own if they like it.
I prefer 3 guides, and the rod I did today was more like 10 degrees for the first guide, 100 degrees for the second, and 170 for the third with the last 10 degrees between 3 and 4th guide out. I suppose technically it is a 4 guide approach but really seems like 3.
When I approach doing a spiral wrap the first thing I do is a bend test on the rod blank and determine where the rod really begins to bend under load, and I look and see where the rod is within 97% straight under load and I mark this spot on the rod blank usually with a piece of tape.
This boundary tells me that all of the guides north of the mark should be on the under side of the rod, and the guides South of this mark towards the reel can be on top of the rod blank. And usually my spiral wrap around will have this mark about in the middle of the spiral wrap.
As I put the guides on a rod I usually start with the underside guides, the ones I know have a fixed specific location and I work my way back to the marked boundary between the bend under load and the straight part of the rod under load. All but the last guide on the bottom will be epoxied into place. I will then usually put the tip on so the top of the rod is done.
Next I will put the last 3 guides on and not put any epoxy on them at this time. This allows me the opportunity to adjust their angle to the ideal locations so I can visually judge the angle of transition in the line from guide to guide. The ideal "look" would be a straight line spiral, but each guide is actually putting a small degree corner or angle in the line and what I want to do is divide out this angle evenly throughout the spiral so that there is not a larger degree of turn in one section of guides to the next.
You can't do this sort of thing on paper. There is no real formula for it either. Every rod bends differently so the guide placement for each rod will or should be slightly different from one rod to the next.
As I tweak the angle of the guides while under load with line in them as if I had a fish on the hook, I look at how the line transitions from guide to the next and what I want to see is the line under load pulled to the center of the bottom of the guide. I don't want it to ride up the sides of the guide when under load.
If you have the angle of the guide too much to one side under load the line will ride up that side and if at too much of angle in the other direction the line will ride up the other side under load as the line is trying to pull itself straight I want to adjust the angle of the guide to be centered on where the line would pull straightest if that makes any sense.
Ideally when I look at the line under load wrapping around the rod, I want each guide to be in alignment with the line, not the line in alignment with the rod which could be pulled too much to one side or the other as it spiral wraps around- especially under load. Casting is not under load in my opinion, only simulating fish on the hook is bending the rod same as it would with a fish on the hook is how I want to visually watch the line flow through the guides.
On to another subject... should the first guide be 0 degrees or not? I am well aware of how line on a reel can be pulled heavier to one side if not going in and out of the reel straight out the front, but there is a little room for play in this area and I have experimented with it and I have concluded that the first guide can be as much as 10 degrees off center without a line stacking problem in the reel.
I started down this road because the very first spiral wrap rod I ever saw I bought at a garage sale 20 years ago, and even then the rod was and seemed old. It is a custom rod in every sense of the word. There is not one word anywhere on the rod and it has a hodge podge mix of guides used on it, but it is a true spiral wrap, but it did not have a first guide at the 0 degree or even the 10 degree position. It only had the 90 degree guide and went immediately to the 180 guides on the bottom. I have used this rod with every baitcast reel imaginable and none of them had a line stacking problem. Not a one of them.
So I know today that my use of the first guide being no more than 10 degrees off center is no where near as extreme as going from the reel itself straight to the 90 degree guide, so 10 degrees off center should not even be an issue for line stacking up on one side of a reel and it has not been an issue for me.
So I now use the strategy of distributing the 180 degrees out over a wider spiral path and adjust the guide placement angles based on how the line is pulled through them under load because that is when it will matter most. If it is a tad off when casting so be it. Not an issue. The line when casting is far looser and free flowing than tight under load with a bent rod and that is when I want those guides to give me the straightest line in the spiral wrap just like the straight threads wrapping around a screw or bolt. If the line is not straight as it flows through the spiral then every degree it is off and caused to make a sharper and sharper turn is when friction will jump up. I want each guide to experience about the same load when under load and not just go with some formula on paper that may or may not be right for whatever rod I am wrapping in a spiral wrap.
I hope this makes sense...
If I did the standard 0 degree, 90 degree, and 180 degree and pulled the line tight under load through that, I would see some serious angles in each turn as the line goes through the 0 and makes a hard turn down to the 90 degree and so on. By doing a wider spiral path programmed in the straight portion of the rod under load so it transitions to the underside after the bend begins, the line on my rods follows the absolute straightest path through the guides I can possible give it. So if you were to put a ruler on the tight line under load from the first guide to the 3rd guide it would be darn near ruler straight through the transition.
For my way of thinking this is the most ideal I can strive for.
So in all honesty, my latest rod finished today I said was close to 10 degrees, 100 degrees, and 170 degrees, in reality it could be more like 8 degrees, 97 degrees, and 167 degrees. It is not a specific science of degrees. It is more of a science of how straight can you make the flow of the line through the spiral wrap portion when under load and rod is bending. It has nothing to do with a straight rod with no load and some formula on paper everyone says works. For me, that is just a guide for a starting point. I let the rod and straightest line flow under load show me where the guides should be. Then I epoxy them in place and go fishing with it.
Some of the first rods I did with a spiral wrap were according to the standard 0, 90, and 180 and even some with 4 guides, and today I don't like them as much as the way I do it now. I really like the spiral wrap around to center up on the bend in the rod under load. I don't want the spiral wrap around to be too close to the reel. I want it as far out onto the rod as I can push it and finding that magic spot between the bending rod and straight portion under load is where I want the spiral wrap to do its thing so by the time the line is reaching the bend in the rod under load, it is all suspended under the rod with no twisting to the rod blank at all. It is a smooth straight line transition all the way through the spiral wrap.
I found some images on line to illustrate what I am trying to describe...
This is a good image of a rod under load with a spiral wrap, and in my opinion this is a nicely done spiral wrap, but I wonder if they tested it under load when they epoxied the guides in place???
Take a look at how the line flows from the first guide on the left, the 0 degree guide, look at how it flows through the 2nd guide and to the 3rd guide. Do you see how the 2nd guide is actually now lifting up the line under load?
That 2nd guide could actually be moved to the right just a couple of degrees and it would straighten that line out through this transition under load. You won't find this out with a straight rod under no load and some degrees from a standard formula off some paper somewhere.
If I had built this rod, I would have caught this slight misalignment before those first three guides were epoxied in place. I would have seen this situation and adjusted that 2nd guide to be in line with the tight line and not lifting it under load causing more friction in that guide under load. On my rods I want to be able to put a ruler across 3 guides under load and see a straight tight line no matter how bent the rod is. I want those guides coming into alignment under load, not going out of alignment.
What is happening here is that now that the top end of this rod is being bent and pulled down under heavy loading, it is bending and pulling that 3rd guide down now causing that 2nd guide to carry more weight of the load in the line and making the line make a sharp turn in that one guide. Take the load off this rod that line will straighten back up between the 2nd and 3rd guide. I am saying I want it straight under load. This rod is slightly out of adjustment, but close. Close enough to work, but is it ideal?
In the photo above, ideal would be a straight line, ruler straight tight line under load from the reel to the 3rd guide. End of story. Make that happen. And to do so with what this rod is showing me under load, the first and second guide now under load should be slightly shifted to the right. Both of them- in order to straighten that line out under load through the transition spiral.
This is why I carefully choose the location of where on the rod blank the spiral transition takes place. You can not simply pick a spot at random. You don't do the wrap around in the bend under load and doing all of the wrap around on the straight part of the rod is not ideal either. Use the bend under load in your favor and adjust the guide spacing and angles to take full advantage of the beginning of the bend and use it in helping you create a smooth spiral wrap transition sort of like how a masted sailing ship sails under an arched bridge. Use the arch (bend) in the rod under load as a way of improving line flow around the rod shaft under load. I hope this makes sense!
This is a perfect example of why following degrees off some chart in some book may not be ideal for every rod!
In this image the rod is not under load, but it almost looks like the line is going straight through the first guide and resting on the 2nd guide out from the reel making its spiral wrap from the 2nd, 3rd, and 4th guide out. It may be an optical illusion, but if the line is resting on the guide insert in that first guide, it appears to be riding up on the left side. If so, that guide could have been tilted over to the left a few more degrees so the line would flow down the center of the guide which is ideal to me and what I strive for.
From this view it almost looks like that first guide is not doing much at all and if removed it does not look like it would have much of an effect on this rod's spiral wrap design. In other words, the 180 degree transition is not evenly spread out from what I see here.
On my rods I want the line under load pulling the guide straight into the rod blank down through the guide stems, not riding up high one side or the other of a guide putting an off-center pull to that guide- a twist pressuring the wrap threads and epoxy sideways under load.
In other words, the guide is preventing the line from pulling straight and rather than that guide be glued in the wrong place, it should be able to adjust to move to where the line pulls straightest and puts the least amount of pressure and friction on each guide. There is an optimal position and it can only be found under load.
This is why I do not epoxy the spiral wrap guides in place until I do a line flow check under load and carefully adjust each guide to its optimum position whatever the degree is- and spacing. Let the rod and line under load show where the truest placement of each guide should be! I know of no better way- not yet anyways...
My .03 cents on it anyways.