Sorry, I can't research ten thousand messages which may have covered my questions. But, all I have read so far does not answer my questions, just creates more. I just don't understand all I know.........? I have read that there is a soft spine AND a hard spine AND separate from boaf of them, there is just a stiffer plane of the blank! uh.....I have so many questions I don't know where to start. BTW I have subscribed to the rod maker magazine but it will take weeks to get my first issue. I think this board is the only place I may find precise answers. I am in the process of building my first rod, friend marked spine on both sections, and mounted the reel seat and cork while I was busy on a phone call. Now, I think the spine is 90 degrees off to the right on the butt section....but the reel seat is already in place. I haven't mounted the guides on the tip section yet.....so......I wonder where to put them.....if I do indeed think the butt section spine is skewed off to the right? Many more questions.

1. Is the spine a finite, definite harder/stiffer weel defined line on the blank? Or is it just a group of fibers that bunch up in a general line on the blank?

2. The home brew spine finder says to apply downward pressure at the extreme tip of the section.....and that if you apply that pressure several inches down from the tip...the spine might indicate differently? What's so precise about this? Then you look at the Cabela's catalog and their spine finder just supports both ends and puts a weight in the middle. This board says that method, option three, is disregarding the spine and just finding the stiffest axis. Is not the spine the stiffiest axis? I'm confused.

I will ask a few more questions, I gotta run, volunteered to help stock some trout and then help some group of kids fish at the creek.

Thanks in advance.

Jim

There is no such thing as a soft or hard spine. The spine is not a thing at all, it is just an effect created by several manufacturing anomolies.

Actually, I think your questions are answered pretty well on the FAQs page here. Have you read it yet? Sounds like you may have.

The spine is not the stiffest axis, nor is it directly opposite the stiffest axis (well, once in a while it is). For general purposes, when the rod is flexed and allowed to roll into its favored position (this is where it tends to settle in and doesn't want to be rolled out of) we would mark the outside of that bend and call it the "effective spine." This is just a reference point. Again it is not a physical thing.


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Personally, I wouldn't worry about it. I think that the value of spine is way over rated and many builders no longer bother with it. Imay be wrong but that seems to be a growing opinion.

Mike

I have two pacbays sitting here that i bought in Charlotte want build using the bumper spiral method, i am going build them on the straightest axis of the blank, just to see how i like it. John

I have two pacbays sitting here that i bought in Charlotte want build using the bumper spiral method, i am going build them on the straightest axis of the blank, just to see how i like it. John

I am just getting started with rod building too - made 3 rods so far - 3 more on the bench. After my first try, I realized that guide placement was much more important than spline finding. I am learning lots of things - how to wrap, how to wrap well so that threads are tight and tie offs dont show. How various finishing techniques work. To spiral wrap casting rods or not. So far, what seems the most important aspect to me is giude placement with respect to the reel seat and the reel when mounted. I have one rod that looks a litte "off" to me when the reel is on and I am holding it and it is under load. My advice to you (and to myself) is spend time testing guide placement - tape them on and mount a reel and test cast - see how it looks to you. If it looks bad - even under no load - because the blank is curved and you went with someone's spline vs the straightest axis - it gonna drive you nuts every time you look down the rod. Or at least it would drive me nuts. Anyhow - that's my 2 cents worth - focus on guide placement - much higher priority than spline finding.

Good luck and have fun.

I always find the backbone on all my rods when I build them. I believe that it stops the rod from wanting to roll when its loaded up. I call it fine tuning...I want my rod to work at its very best.....you dont get good performance from a rod thats been poorly made.......same as a car...it doesnt perform well with the timing out. My advice to all new rod builders is to find the spine/backbone and build a great rod from there.

Mick Larson
Melbourne Rod Builders Club
Melbourne Australia

Guide position determines rod stability, not spine orientation. Many of the old rod building myths are dying out, but some remain so deeply imbedded that it takes a bit more time to root them out.

Nothing wrong with finding the spine and using it to your advantage, but you cannot use it to make a rod stable or to prevent rod twist.

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A blank can be manufactured with a very strong and consistent (along 1 axis) spine. With guides positioned along the outside of these flexed blanks (for a spinning or spiral wrap rod) no twisting was seen when the rod was loaded in a casting position. As Tom suggested, find the spine and see for yourself if it can be used to enhance the performance of your rod.



Edited 1 time(s). Last edit at 05/11/2005 10:21PM by Moderator.

I find the suggestion to disregard the spine in building a rod to be a very difficult idea to buy into. Is the EFFECTIVE spine the stiffest axis of the rod? Reading FAQ's number 2 tells you how to find the effective spine. Question 5 step 1. says spine on top - more power on forward cast......why is that? Step 2 says spine on bottom "puts the spine in strong play on the forward cast"? Again, I ask, is the spine the strongest/stiffest axis of the rod? I think there is something here I do not understand about the spine and how it works in the action of the rod. I am assuming the effective spine is the stiffest/strongest axis of the rod.....and therefore my answer to step's one and two would be exactly opposite to the explanation's provided. Furthermore, FAQ 5 says three options to placing the guides and that the stiffest and softest axis are not 180 opposite each other and yet you can supposedly find the stiffest axis and build it with the stiffest axis. What is the difference between the effective spine you are finding in FAQ #2 and the stiffest axis? Also, FAQ 5 step 3 says put stiffest axis on top, more power fighting a fish.........but step 2 says spine on bottom gives you more poweer lifting the line and fly off the water? Apologies to all. I am not trying to pick apart anything and shoot holes in it. As I mentioned earlier, I just don't understand everything that I read. Now, having read all of the above, and the FAQ's I "think" the spine of my butt section is 90 degrees to one side.....and not on top or bottom. Has anyone ever checked for the spine AFTER mounting the reel seat and cork, and before placing any guides on the butt section of a two piece rod? Did the effective spine stay where marked or did it move as in my case? I am goin to take the suggestion of lining up the tip section spine with the axis I am stuck with on the butt section, tape on the guides and try it out. Then I gonna build it.....give it away and start over. Like the person said above, if I know something is not correct in the rod it is going to drive me nuts every time I use it......unless I catch my first big trout on it, <grin> . Unfortunately my friend mounted the reel seat and cork while I was busy on the phone. I will have to buy another blank set, find the spines, mount the reel seat and cork, then try to check it, just to find out if my friend did it wrong, or it changed after the reel seat and cork were mounted. This would raise more questions on how to build a good rod if were to be true. I again apologize for length of post, I feel a need to defend myself and the reason I don't understand.....guess I am just plain dense. I also know nobody is going to plow through this whole diatribe and address all my questions and try to provide good answers. Oh well.....I vented. Probably get booted.

Jim I hope someone with proper knowledge-not me!-can answer your questions and do it well.

From what I understand, the spline IS the stiffest area on the rod and guides can be put either on it, or oppisite side of it, depending on your preferance to it being "softer" or "stiffer/stronger". If the spline is dis-reguarded it may tend to make the blank "roll" to the softer side of it......?????.....?????

DR

I think what can be confusing to some is just the terminology around the spine. Hearing the term “spine”, most people immediately picture something that is stiff. But bear in mind which spine you’re talking about. As Tom said, the effective spine is the relaxed position under a load. The effective spine or relaxed position tends to represent the least stiff axis of the blank. When you seek to find the effective spine, you're putting strain energy in and the rod seeks the lowest state and comes to equilibrium. There can be one or more relaxed positions, and the reason that the stiffness 180 degrees, or opposite each other aren’t always equal is that many materials don’t have the same stiffness in tension as they do in compression. So when you bend the blank in one direction, the material on the outside of the curve under tension will respond differently when you reverse the situation and put those same fibers into compression. This effect can be particularly pronounced in graphite fibers.

If you start to turn the rod away from this relaxed point, you'll meet some resistance and the points (sometimes 90 degrees) on either side of the relaxed spine represent the stiffest axis….some call this the jumping spine.

One of the best ways to find the stiffest axis on the rod is to mount and level the rod, hang a weight from the tip and then rotate the rod to measure the tip deflection as a function of orientation around the center axis. You'll often see the tip cycle up and down and the stiffest axis will carry the applied load higher, or with less deflection. There’s also no guarantee that the spine will follow a straight path down the blank. So then you can see this effect by measuring the difference in power under various degrees of loading. Typically, on rods I’ve measured that exhibit a pronounced jumping spine, the difference in power between the stiffest axis and the relaxed spine is usually in the range of 5-10%.

I also agree with Tom in that the guide position will determine the rod stability. But it could be argued that the spine can have an underlying effect. For example, if you build on the stiffest axis, or off of the effective spine (off relaxed position) the then the stability of the blank could compound any instability in the guide set..... guides on top for example.

mark

BTW, Rich Forhan wrote a fairly thorough article on Spines which was published in RodMaker a while back.

That's good info. On the CCS scale, the difference between the stiffest and softest axis's is about .2 at best. That's not much. Very little, in fact. It could be greater on the very heavy saltwater blanks, of course.

One other point - because the spine is not a physical thing, it does not "run" up or around the blank at all. It simply is an effect that causes the blank to prefer one flex position over others. When you attempt to locate the spine by utilizing various lengths of the blank, you'll get different spine positions due to the effect being considered over either more or less area. But the spine isn't "spiralling" around the blank as some think. The effect is simply falling in a different place as you change the length of the blank you're testing.

Keep in mind that the spine effect is created by various manufacturing anomolies. Yes, it will move as you modify the blank. When you assemble multi-piece ferrules the length changes and the spine effect falls a few degrees differently. It certainly could move when you add a handle and seat, although that is so low and near the butt where the rod doesn't flex much, that it surely won't move much if at all. Mark your sections and then assemble and align your marks. Now check the fully assembled rod and you'll note that is has probably moved by a few degrees. Re-mark allowing for this movement and proceed to build the rod.

The effective spine is the outside of the curve when the blank is in a pressured curve and allowed to roll to it's desired position. So this would be the softest axis of the blank.

The stiffest axis can generally be located by sighting for the straightest axis of the blank. Put the tip and butt up and the belly down, and you'll have the stiffest axis to the fish. This may or may not be 180 degrees from the effective spine.

If you put the guides on the bottom of the rod, it will never try to twist on you regardless of spine position. If you put the guides on top of the rod (casting style) it will always try to twist on you under load regardless of spine position. Nature of the beast.

Jim,

You would never get booted here for asking a question in a civil manner. And many will attempt to help you in any way they can. That's the nature of this place.


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I too no longer concern myself with spine and build on the straightest blank axis.

Question: Given that spine was such a big deal for so long in the rod building community, could it be possible that spine on the old bamboos and solid wood fly rods was much more pronounced and had an actual effect on the rods action; an effect far greater than what we experience with today's modern blanks, thereby causing the old-time rod builders to write in stone about the necessity of the importance of determining spine?

Mr. Kirkman,
Thank you for the great reply. What a class man you must be. Also thanks to Mark and all the others for great explanations. Too many to quote. But in general.....I understand the spine now. In fact it is such as I suspected. But......too many comments can be made which are meant to be precise and end up vague or questionable. For example....you read comments that you support the rod section on each end and place a weight n the middle....the outside curve is the spine. Or you read comments about the "top". If you support the ends and place a weight in the middle.....the "top" is not the same as supporting the butt end of the rod....at a 45 degree angle and then pushing the "tip" end down toward earth......now the "top" is not what the "top" was. So many words about the same subject but going from a bump, to a spine, to a stiffest axis, to a straight axis can still cause a little wonderment. I do not want to beat this to death, but now that I "think" I understand it.....I would like to just verify it in my own words. Because......I am still not to sure if there isn't a fly in the ointment so to speak. I NOW only care about the stiffest axis. Forget the spine. I myself only want to know where the stiffest axis of the entire rod is, so that I can choose to mount guides on top or bottom....and NOT have the stiffest axis skewed off to the side. So...........is my thinking correct.......a big homemade mixing bowl might be 1" thick. As it sits on the counter viewed from the side......it is a "C" laying down. That bowl, from a side view.....is going to have an ID....inside diameter.....and an OD.....outside diameter. If this were a rod section....supported on boaf ends:

1. is the inside diameter the softest axis because it rotated up......?

2. does that make the outside diameter the stiffext axis......becaust it forced that position?

3. If I look at it that way.....if I want the stiffest axis on the top of my rod to fight a fish on....I would put all
the guides on the INSIDE DIAMETER of the bowl?

4. If I want the stiffest axis on the bottom of the rod for casting forward I would place all the
guides on the OUTSIDE DIAMETER of the bowl?

Please say "YES" to questions 1, 2, 3, & 4.....and I will have all that I want to know. I just want
to know............you know?

Very much appreciate all the posts. I actually had thoughts of finding the stiffest axis by placing a drying motor (which I don't have), but a 2 rpm motor facing the ceiling, mount the butt end of a rod section in the motor so that it is vertical, off to the left about 4' hang a fixed eye bolt from the ceiling, connect a string to the tip of the rod, run it through the eye and let it hang down, and attach a weght. Then turn on the motor and watch it go round and round.....and mark where it raised the weight the highest.....and call that the strongest line of the section. Then do the same with my other section of the two piece rod. Then, mount the reel seat and cork "temporarily", not glued in place.....and do it again to find the possible newest stiff line of the rod, then re-mark that butt section, then line the two sections up......connect together, and then do the bowl method, (support both ends and weight the middle) for a final tune up. Then re-mark everything and then glue on the reel seat and cork......and commence tying on the snake guides. That is of course.....if the answer to questions 1 thru 4 are all YES!

Sorry for length of post. I never have been good at "ten words or less".

Again I say thanks to all, and thank you Tom Kirkman for a class board.....that has to evolve from the moderator. Well done Mr. Kirkman.

Jim
".....and remember son, if you're not the lead dog.....the view never changes....."

I think you're on the right track. At least you know what you want to do and how you want to position the rod.

Mark gave you a good method for finding the stiffest axis. Or, you can sight down the rod and find the natural bend. When you have the blank in the concave position (like your bowl, belly down, tip and butt up) that would be the position you would want the rod to be in while fishing. So your guides on fly, spin or spiral wrapped casting would go on the bottom of that concave shape. If you were building a conventional guides on top rod, then the guides would go on the inside of the concave.

Normally this concave shape is fairly easy to determine by sight alone, but if you find too many twists and crooks on your blank, then Mark's suggestion on finding the stiffest axis will be your best bet.

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