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Rule

I have two questions and a comment;

Question for Robin: Could you please give us more info on what you mean by Quarter Circle load or deflection? It likely involves 90 degrees in some way, I guess.

Question for Frank Paul: Could you explain how you measure the fundamental modal frequency?

And a comment: Mr. Garrison was, I believe, a railroad engineer, and/or structural engineer. His cantilever beams were mostly linear and designed to deflect no more than a couple of thousandths. These are the design equations he carried over into rodmaking.  With negligible  deflection his equations were simplified, but when deflections are significant (rods do bend) there  is  a  dy/dx  term that  is dealt  with in  the dreaded Bernoulli-Euler second order differential equation. I like to think that kindly Mr. Garrison tried to spare us this discomfort by tailoring his stress curves.  And he did it all with a slide rule. Thanks, Mr. G.

These taper discussions are really getting into the heart of rodmaking.  (Bill Fink)

    I have vague and evil memories of Bernoulli, and even worse ones of the fluctuations.

    If you fix a rod handle to a ceiling beam, or just stick it in a suitable tube clamped to a ceiling beam, you just hook a spring balance, zeroed for use upside down, in the tip ring and pull down on it until the tangent to the tip is a right angle to the tangent at the butt. The reading on the spring balance is the quarter circle load. Do it a few times, with different rods and you achieve adequate consistency. You have just performed a simple stress/strain experiment. If you know what the line rating of the rod is, as in its the line that YOU think matches a rod best, you can draw a nice little graph which relates the quarter circle pull to line weight.

    Should you wish to modify the line weight rating, or perhaps, the length of the rod, you then apply this information to my simplified formula which is that Deflection is proportional to the weight applied to the tip, the third power of the length and inversely proportional to the fourth power of the diameter. And the easy way to do it is to use simple percentages.

    I've given examples before of how this works, but will repeat them if anyone wants me to.  I can tell you that it certainly does work, but extremes are to be avoided as other factors, less capable of empirical analysis, intrude. (Robin Haywood)

      I am interested in your measure of Quarter circle.  It might become a kind of measure of a rod.

      Let me ask some questions for clarification.

      What are the assumption when you identify the line weight when the rod shapes a quarter circle.  You mentioned "pull down the top until the rod shapes a quarter circle"?  You did as RIGHT angle.

      Question 1:  What is the RIGHT angle?  How do you decide it?  What does it mean? I thought that the quarter circle shape is a kind of your measure, is this right? Yeah, we can make the shape in such occasions as hooking a fish.  But it depends on the size of fish, depends on the length of the rod, and sometimes overloaded rod would make a quarter circle too like fish is on, on the boat in the sea.

      To make a quarter circle as a measure, you must have several assumptions such as;  for 7 feet rod,  quarter circle weight = so and so, then best hit is  #x line for 8 feet rod,  so and so.

      Let's say as QC since quarter circle is too long.

      Question 2:  Can QC or QC load be a measure of deflection in a CASTING?

      When moving a rod, the rod does not necessarily make a QC form when we cast a  certain length of the line. In most cases, maybe the rod is not bent so much.  Then why QC form becomes a measure even if we assume the load(line to fish), acceleration of rod, the length of the rod?  Do you have some other algorithm between deflection and QC form? QC form might be a maximum deflection  for a line weight and under a so and so acceleration of the rod, I imagine.

      So far, I just feel the QC form is related to the maximum or a limit of deflection assuming something.  What’s that something?  (Max Satoh)

        I think that, apart from the fact that the math suggests that 90 degree deflection is something of a  break point, the obvious thing about any deflection greater than 90 Degrees is that it would necessarily drop the rod tip below the highest point of the rod, resulting automatically in a tailing loop as well as a dramatic loss of casting energy.  (Peter McKean)

        When the tangent to the curve at the tip intersects the tangent to the curve at the butt at 90 degrees then that is what I am calling a quarter circle deflection, even if the curve is not the arc of a circle, but a parabola (In the correct use of the term) (More or less)!

        The QC load IS a measure of deflection, isn't it, whether that deflection is caused by a fly line, a trout or a tree makes no difference.

        In most casts the rod will not be loaded to a full quarter circle, what is important is that it should never be loaded BEYOND a quarter circle.

        Assuming that you don't want your fly line landing like a half uncoiled snake and that you don't want to shorten the life of your rod by repeatedly operating it in overstress.  The QC form is the mathematical constant for deflection in the formula. There are four factors, deflection, load, length and diameter. It doesn't really matter what the thing does when fishing, we are not trying to fish with it, indeed, we like fishing with it so much in fact that we want to make a whole set of these things for different line capacities and different lengths, but all with identical actions. If you don't like the action of a rod all the mathematics in the world won't help. If I make you a rod and you say you want it a little stiffer in the butt then unless you can put numbers on "Little" "Stiffer" and "Butt" I'm going to be guessing, am I not?

        Even in the unlikely event that you can do that, and express them in the correct units as well, how do you actually know they are right without applying them to a rod and trying it out in practice? There is a time and place for calculation, and an equal one for practical experiment, one cannot supplant the other.  (Robin Haywood)

      What if you substituted a series of standard weight units for the spring balance, and used a standard deflection of say 1/3 of the rod's length for measurements. That wouldn't change your basic concept, would it? Couldn't you then calibrate this standard deflection into line size for any rod  using intuitive estimates as a basis or starting point? For example: my intuition (and Garrison's) says that his 212 is a weight  6 and measures a deflection of  1/3 rod length with 1400 grains load. Then any rod that deflects 1/3 with 1400 grains grams should be a weight 6. And wouldn't it be possible to get a really good measure of rod speed by measuring the deflection angle at the very tip under this load? The higher the angle, the faster the rod.  (Bill Fink)

        I think the tip angle is not accurate enough to measure “rod action”.

        Consider:

        Rod #1  - Very slow action  - This would deflect a lot thru the whole rod and result in a tip angle of X

        Rod #2 – Fast action (having a very flexible tip) – This would deflect, under the same load, mostly at the tip but since the tip is very  flexible could conceivably give the same tip angle.  (Al Baldauski)

        The first part of your post is exactly in line with my model, as I said in a recent post, you can use any curve less than a quarter circle that you can measure consistently.

        The second point is only an estimation as the taper form will tend to affect the issue. How would it help us with compound tapers?  (Robin Haywood)

      I'm wondering how this would change if, instead of hooking the spring balance to the tip, you string a line thru the guides and hook the spring balance to the line?  I'm thinking that the number of guides and their placement has to be an important variable in rod design.  (Frank Stetzer, Hexrod, Taper Archive, Rodmakers Archive)

        In this particular test it makes absolutely no difference.

        In a real life fishing situation the guides only influence is the amount and position of their masses, all other things being equal, guides should be as light and few as possible, also as far off the rod as possible!

        I said "All other things being equal"!

        There seems to be an opinion in some quarters that guide spacing is one of the mystic arts, in fact the only criteria is that they look OK!

        There are rules, you want one about 4" or less from the tip, and the stripper guide needs to be as far forward as you can tolerate, for distance the use of a double stripper whose centers are about 2" apart seems to me to offer some advantage.

        The weight of a heavy set of rings can easily cost you a whole line weight in terms of stiffness and there is no rod that will not work best with no rings, handle or reel....

        This is enough. (Robin Haywood)

          Do you have a basis for your ideas on guide numbers and their placement?  I have found that number and placement of guides can make a big difference in the way the rod casts at both long and short distances.  (Harry Boyd)

            Quite right, you can really kill the action of a rod by placing too many too heavy guides too far up the rod.

            They act as a permanent load, of course, thus detracting from the weight of line that can be used.

            But the actual spacing plus or minus an inch, will only make a difference if it seriously displaces the center of mass of the whole rod towards the tip. (Or the butt, come to that).

            I think I did go on to say that the number could make a difference, unfortunately too few can set up a bit of line flap which mitigates against the advantage. I've never found that the old adage of one per foot to be very wrong, most people would add one to that. For tournament casting I should like to try a rather stiff line combined with smooth and large rings and not many of them. Bet I'd learn something.  (Robin Haywood)

              My point about guides is this:

              If we can tell something about a rod by seeing how it bends when a weight is hung from the tip, its going to bend differently (less?) if we hang the same weight on a line thru the guides. Some of the mass of the weight is supported by each guide, depending on the angle the line is making at that point.  It is like we are hanging separate smaller weights on each guide.

              I'm sure an engineer could express it correctly.

              I forgot how this discussion got started but thanks to everyone who has contributed, especially Max's new viewpoint from half a world away.   That's what the Internet is for.  I'll print it all out and take it with me when I visit the in-laws next week.  (Frank Stetzer, Hexrod, Taper Archive, Rodmakers Archive)

                Do what I did, many years ago, bend a tip to a quarter circle against a white board, with line through the rings. Then cut the rings off one by one and see what happens. Before you do this you might wish to draw the quarter circle on the board that results from the same loading applied just at the tip.  I can TELL you that there is no difference (if you do it properly), but that’s not the same  as you proving it to yourself.  (Robin Haywood)

    I have just received and read (reread) several chapter of Mr. Milward’s book. Thank you to the relevant person.

    First Observations:

    1. First I find those Who find in the text. Heat treating is bad. Should reread it again.  To the point of color change was the evil parameter. He also discusses heat as source of relaxing the various structures, an aid in realignment.

    2. I think he made a random swoop at the length of the fiber vascular bundles (power fibers, in his own words). not based on cell length

    3. He relies on Mr. Bokstrom to give computer meaning to his theories.

    4. He changed the design criteria from stress to flex, deflection, etc.

    5. He definitely honors Mr. Garrison but wants to squash static stress analysis. While he spends a great deal of time tearing it apart he describes the math as giving a straight line taper. later he describes this as His fundamental design starting pt. but dismisses the previous fact. He obviously, or from what was written, did not use a computer model and manipulate the taper using G math to change the character of the rod.

    And Robin

    And now what do you have with your rod hanging from the ceiling with an 90 degree tangential bend. Is this an example of dynamic flex or static flex. certainly an alternative if you have a wall & 8' of graph paper. It also took a rod, tough if I haven't built one yet. and what if I don't like it.

    6. He seems to describe rods only in terms of speed, slow fast, etc. I need to read some more. I don't directly grasp how to build complex rods yet, like a double para.

    7. He also seems to appreciate straight fibers and nodes in a finished rod. However he describes Hardy's sawing methods with approval (a little inconsistent) He also seems to generalize that all is well if the rod doesn't fail (sloppy). But I'm sure he really doesn't feel that way.

    This a great book, and an enjoyable read from a brilliant mind.  (Jerry Foster)

      I don't need to reread Milward. You just missed my point(maybe I wasn't clear enough). I used Paul Young as an ex.  Because he ran his culms through a ring of fire created by a circular tube with holes that was fed with pentane gas. And I don't think anybody who has ever seen an original Young or even just a good clear picture of one would miss the fact that they have definitely been heated to the point of color change. I don't recall ever seeing any rod by any maker that uses flaming that the flaming hasn't produced a color change, sometimes very dramatic! With the exception of Darryl Hayashida who flames his on the pith side so he can still build blond rods (of course he gets a  GREAT DEAL  of color change on the inside of his blond rods.) OK we all agree that the densest power fibers run on the outside of the culm where the flaming is done. If you've never been to Ron Kusse’s web site, visit it and look at the rods he calls The Black Trolls. I would think that they are about as extreme an example of color change as one can get without turning the culm into worthless charcoal. Therefore if Milford is right on this particular point please explain to me why these rods are not failing. Jeff Wagner’s Patriot series, many of Marcelo Calvielo’s rods are heavily flamed and the list goes on. Maybe I'm just dense, but common sense tells me if Milward is right about this subject there is one heck of a lot of builders who are doing things wrong. (Will Price)

        I can't tell you if he is right or wrong on that particular point.  It's obvious to me that Mr. Young's rods are doomed to disaster.  (Jerry Foster)

        In my testing of heat treating which I have done with oven and torch the results show simply one thing. If you know what you are doing it does not matter if you use a torch or oven. Heat treating  to color change is fine if you know when to stop.

        Mr. Milward  by his own admission flamed a rod for heat treatment and achieved a poor result. All this shows is he either 1: Had bad cane or 2: Did not use the proper technique for heat treatment with a torch. Since he had a bad experience with flaming he does not support it for heat treating. Not very scientific method of testing. He simply blames the method, instead of blaming the maker for the failure.

        Heat treating with a torch is a very good method of heat treating. It allows a very controlled method of cooking cane. The application of heat properly and controlled is where the craftsman tends to get confused.  Charring and blackening the cane is not necessary in flaming for heat treatment and you might risk problems. A slow flaming of the cane slowing changing the color with control you will achieve the desired result.  I have 2 bamboo ovens and I choose to heat treat with a torch because of the superior control I have over the even application of heat.

        Heat is Heat controlling its application is the trick.

        Milward’s book while very good for the most part is his opinion based upon his preference in technique and materials, it is not science  (Adam Vigil)

          I'm going to defend Milward's conclusions on heat treating and flaming.  I believe he makes a good case based on the following evidence & logic:

          He claims to have done ferrule repairs on many (I think he says over 100) older rods.  The ones which were originally flamed, he says, are usually brittle and the cane crumbles when squeezed with a pliers.  The blond rods do not.  Then he reviews the published studies on the effect of heat on
          cane.  The chemical/physical changes, which we want to make the cane harder or stronger or stiffer, will eventually lead to failure by breaking down the large molecules holding it all together. This explains the brittleness of older flamed rods, and leads to his recommendation of no flaming and minimal heat treating.

          To me this makes sense. If we are building rods for ourselves (that's me), maybe the tradeoff of a shorter life for a livelier rod is worth it.  But if we are building rods we want to be fishable many years from now we need to be concerned with this, just like we are concerned with the longevity of our glue.  (Frank Stetzer, Hexrod, Taper Archive, Rodmakers Archive)

            To play devil's advocate, you tend to view Milward's conclusions with a certain degree of skepticism.  The results published are based on pseudoscientific testing on quite a limited sample size.  I haven't heard of say PHY rods experiencing fatigue or ferrule failure related to the flame treatment (and I have one friend that are dedicated PHY collectors and two more PA rodmakers (one of whom is Bob Lancaster, who have been building rods since the 70's with no reported problems using flame to heat treat).

            Milward also wasn't too keen on using 350 degrees, even though if you read garrison he did his own extensive testing as an engineer and arrive on his regimen, using this temperature, based on his own tests. And no one has ever said Garrison rods fall apart (unlike say Gillum rods of a certain period that tend to delaminate, though that  was because  a glue  that he used for a short period).  (Chris Obuchowski)

      Thank you for digesting the book.  It helped me very much.

      May I ask these to you?

      4. He changed the design criteria from stress to..flex, deflection..etc.

      Did he show us a "design method" which uses flex, deflection which is enough to convince us on,  how we should draw deflection or deflection curve as a "method" or as a part of "method" and how we should utilize it?

      I couldn't find any proposed "design method" as Mr. Garrison did. Do you think it is his design method?, to take a high speed photo, calculate angle, calculate stress values and draw stress curve? What is the positioning of this stress curve for him?  I think this stress

      curve is also a static stress curve which is made in a certain situation, when the rod is fully bent.

      5. He definitely honors Mr. Garrison but wants to squash static stress analysis.

      Isn't it a careless shortcut to say this in public?  (Max Satoh)

        I was looking for a grand unification theory, not to be found be me as of yet.

        No I have not found a process. What I see so far is a bunch of stuff that looks like it's sole purpose is to invalidate all of G's stress evaluations, but nothing to replace it except comparative analysis.

        Controlled modification to a known taper.

        I was looking for the detail of how to arrive at that dynamic stress/flex solution that he talks about.

        OK, maybe I was a little harsh, but if I may quote from p 101

        Speaking of Garrison's system:

        "The mathematical matrix used to link all the above was fiber stress calculations, which were actually meaningless!"

        So we are free to interpret his intent for ourselves.

        Interestingly, I put Mr. Milward’s tapers into the Hexrod program and I got EXACTLY the result I would have expected. The curve and the stress values all reflected exactly what Milward said he was trying to achieve with the taper. So for that part I'm not convinced that The Garrison model does not reflect exactly what his (Milward’s) unpublished Dynamic stress model would hope to achieve.

        Maybe some of Garrisons assumptions were not complex enough or, like the 4 factor for gravity were simplified too much, but the results reflect what we know about rods pretty accurately. The hard part is understanding what the stresses are saying, regardless of who derives them.  Which of course drives me crazy because I'm right back where we started.  (Jerry Foster)

          We sometimes focus ourselves into rodmaking, but I felt myself that some important information is not identified for the view point of clients.   Rodmaking metrics are well discussed here but how about the metrics which most clients want to know.

          For instance, rod weight is very important metrics.  Are you conscious of rod weight when you design your rod?  Does your design tool calculate possible rod weight as a complete rod (with grip, reel seat attached)? How about the center of gravity of your rod when a certain weight of  reel is loaded on your rod?  Rod balance is another important factor for our client.   Are you conscious about this when you decide your reel seat style such as uplock, downlock or butt extension is needed? Are you recommending to your client, to use so and so weight of reel in order for him to use your rod in best balanced conditions?

          I asked Robin about his quarter circle load from these points of view. I thought a quarter circle load may say something about the maximum effective load for the rod.

          How about try to identify those metrics for a client and reflect those in to your rod design method?  As well as for our rodmaking metrics?  (Max Satoh)

          Good job, Jerry,

          Maybe some of Garrisons assumptions were not complex enough or, like the  4 factor for gravity were simplified too much, but the results reflect what we know about rods pretty accurately.

          Sometimes simplification is required to make a method practical.

          As I mentioned several time, I guess I was successful to draw deflection in motion, whether it is exactly precise or not.  My tool can draw different stress curves according to the different cases of rod movement. When a rod is moved as pick up motion, the rod will deflect as a pick up motion, and when a rod is moved as translated (parallel step aside), it will deflect to the effect.  By this, one rod deflection varies from one motion to another. Stress curve is also the variable in the world of dynamic, or to say natural, interpretation of a rod in motion.

          The important point lies here.  Then What is the design criteria, standard, or bases among those variable thing? We have to assume one situation if we want some equation to be implemented as a standard. That is the 4 of Garrison.  Even all of us can draw dynamic stress curve, we have to share the same assumption, if we need to discuss and compare the results to each other. We can draw Garrison's stress curve using his factor as 4, or 5, or 6, it's free for everyone. But the resulted stress curve cannot be used to compare nor shared among people. Then we need to decide one situation to be shared.  Again, that is the 4 of Garrison. It is well considered number.

          4G is the speed that will translate (move step a side) the rod in 9.8m x 4  per  secsec.   This  is  39.2m/secsec  = 129.4feet/secsec= 3feet/0.023secsec That is move the rod in parallel 3 feet in 0.023 sec.

          This comes from;

          Weight = mass x gravity acceleration

          4 x Weight = mass x 4 gravity acceleration.

          Force of inertia = mass x - acceleration

          4  x force of inertia = mass x -4 acceleration

          gravity acceleration = 9.8m/secsec

          The hard part is understanding what the stresses are saying, regardless of who derives them.

          Doesn't it mean that Stress curves are variable in natural world?  If he took another shot of picture, he must have had another stress curve.  So we have to have the shared assumption, 4G speed, Translated movement. Rotated rod movement will show the different stress distribution for the same rod.

          Which of course drives me crazy because I'm right back where we started.

          Congratulations.  (Max Satoh)

Rule

It seems to me the Quarter Circle technique and the Common Cents technique (which no one has yet to mention in this discussion) are the same methods of trying to evaluate the performance of a rod in a situation more like that of casting.  The QC technique measures load at the extreme of the dynamic situation while the Common Cents technique measures load at a deflection equal to 1/3 of the rod length  (probably about half way between no deflection and maximum deflection, a happy compromise). Either technique may be able to identify the approximate line weight for a given design but it won’t tell you anything about how a rod behaves throughout its full spectrum of performance, ie:  close in, mid distance, or long shots.  For this I think we are still left with trying to “interpret” a stress curve to get a sense of the “feel” a rod has.  And this can still be done with Garrison stress curves and a lot of experience in casting different tapers.  Since the rod never bends in a true circle, then perhaps and evaluation of the rate of change of the tangent line at 5 inch increments  would identify “character” of the rod under a given load or for many different loads.  I think this is partially what Common Cents tries to do with the measure of the tip angle at 1/3 deflection, but that angle is more dependent on the very tip than the whole rod.

Re: Max Satoh’s question:  What about weight and balance?

I built a Para 15 and found it brutally “tip heavy”.  It was real work, not fun, casting it. But when I added 3 ounces of weight to the reel, it brought everything into balance and it became a “sweet” rod to cast.  So rod weight or total “system” weight is not so much a factor as is “system balance”.

These are my observations and comments on this thread so far. Unfortunately, I don’t have a clue on how to incorporate all design aspects into a Holy Grail.  I’ll look forward to seeing Max’s approach when the bugs are worked out.  (Al Baldauski)

    Thank you for explanation.   Your explanation hit me on some idea. There is a method to classify a rod action into Fast, Medium, and Slow. I long had a question about it.  Almost all the clients of our rod, fly fishers are explained by their rod shop like, "this is a Fast rod".  The definition of Fast action rod is very similar to Common Cents technique.  It seems to be hard to make sense of rod action, do you?   Fast rod definition is like this, 1/3 of entire rod will deflect...

    When I developed the questioned code, I thought, How to draw a target deflection curve as an input to the program. (the program has an ability to read the deflection and calculate dimension as output).  It is very difficult to draw a deflected line by hand or even if we use a computer. Especially butt front is difficult to draw. We cannot draw the difference  between  0.1  degree  and 0.11 degree, though the program will identify it and calculate. (so the help of stress curve is necessary) Then one thing I though is, to show the deflection by Angle which is drawn between tip top (which is bent) and the end of the rod. (assuming the rod itself is standing perpendicular).   Though this metrix is not firm yet, it may become a factor to display an attribute of rod action than the definition of existing Fast, Medium, and Slow. For instance, standard bending angle up to 15 degree (means very Fast), and like that. Now I am considering how to display my rod action by this kind of thing. I hope it should improve the visibility of a rod if I sell it through Internet.

    Like this, I want to identify those metrix which improves the visibility of our rod for the client who are going to buy our rod.

    Thank you for your example of rod balance too.  Paras CG is at apart from grip.  I think the balance of the rod which is to be built, and the recommended reel weight are one of the design factors.

    I am still struggling with the inconsistency.  I will try to fix those inconsistencies, give me time. If someone could invite me on one's account to US, I am glad to visit and fix the version differences, it is not difficult to work at the problem location.   Doesn't any  one company for it? <g>

    Instead, I will show you the output of the program via my web soon. The supported tester can look into some output excel files in "data" folder of download package which implies how this code works.  (Max Satoh)

      I think an average angle of deflection will not accurately characterize a rod any better than a tip angle of deflection since a slow rod bends more uniformly throughout its length  whereas a fast rod bends mostly at the tip so these differences are not apparent.  (Al Baldauski)

        If a slow rod deflects uniformly and it is really slow, my deflection graph will show the tip top of the rod is on the wider angle than faster rod.  It seems visible.

        And when I stretch or shorten a rod by copying the deflection (degree of bend), the angle is the measure for target deflection. Interesting result is when I shorten a rod by shortening stress curve with the stress values unchanged, the resulted deflection is less than original rod. (becomes faster) When I shorten a rod by copying the deflection angle, the resulted stress curve is higher than original rod. (becomes slower)  (Max Satoh)

        A 'quarter circle deflection' is a bit of a misnomer. A fast rod will not bend into a true quarter circle - but the tip might. In fact the tip could bend past a quarter circle. The radii of bending and where they occur in a rod bent to a 'quarter circle' would more usefully characterize the rod than an angle at the tip.

        A large radius in the butt and a small radius at the tip equals a fast rod. One radius right through from butt to tip (a truer quarter circle) equals slow. And then there is the spectrum in between with radii changing linearly, parabolically etc. from butt to tip.

        Now if someone can tell me how, working backwards by using the radii of bending generated by a presumed load, you could determine  mathematically what the section of the rod should be at any given point I would be really grateful.

        It would mean that you could draw any desired curve/curves (which would describe the rod under bending), assume a load/loads (which would equate to line weight and distance cast) and design the rod to suit. Not asking much is it?

        Any takers?  (Stephen Dugmore)

          In theory, IF a rod action (deflection curve) can be described mathematically which will produce a “good rod”, for example: the angle of the tangent line at five inch increments, this could be used to back-calculate stresses and hence diameter.  As with most calculations, starting assumptions and approximations would need to be made but it’s possible.  The smaller the increments, the better the results.

          This would involve approximating the deflection from one increment to the next for a fixed load based on the deflection curve provided, taking into account the shortening effect of each successive increment due to the deflection to determine the actual moment on that section, then calculating the required cross-section that will allow the given deflection at each point.  Then convert that cross-section into a quad, penta, or hex  “diameter”.

          I’m not saying I’m the man to do it, though  :-)   It would probably take more of a computer wiz than me.

          I’m not sure, but I think this is what Max Satoh is doing or something like it.

          Again, all of this assumes a predefined curve and the question that started this whole discussion is:  How do you define a “good” rod, then how do you design it.  Those rodmakers of experience probably already have the tools (Hexrod, RodDNA, and INTUITION) to do the job.  Something more elaborate might make the leaning curve less steep for the beginner, though.  (Al Baldauski)

          If you still have the package for testing in your PC which was downloaded from my web,  please look into the expanded folder and try to find "data" folder on 2nd level.

          You may find several .xls files.   Those are generated via my tool. Take one and open the worksheet named as "Graph1" or "Graph6",  it shows up the mentioned deflection curve.  (Max Satoh)

      We have tested a great many rods using the CC method and have found good agreement with angle measurement vs subjective rod action. Measuring from the horizontal with a pretty fancy protractor we find agreement with the publicized values of: below 59 degrees - slow action. From 59 to 63 degrees - moderate action. From 63 to 66 degrees - moderate/fast, and above 66 degrees - fast action.  (Bill Fink)

      From what I've seen by testing my own rods with the Common Sense system is that it is also possible to trick the Action Angle by making a slow rod with a very fine tip, it will give an action angle reading like a fast rod. One thing I also noticed is that my rods consistently read one line weight lighter by the Common Sense system than I and others who have cast my rods think they are. When I tried them with the line weight that CC dictated, they were noticeably underlined, too much tip bounce and much less line control in the wind.  (John Channer)

        Like many of you, I intuitively questioned the Action Angle theory in the CC plan.  We ran many tests on a wide variety of rods and did find good agreement with the Action Angle  findings. I think it has a lot to do with the greater "foreshortening" that happens with softer rods compared to those having a high action angle as was previously mentioned. Where I do disagree with the original CC Plan is that it seems to give consistently low line size results. Maybe this is because there seems to be some kind of a "prestige" value in fishing lighter lined rods. Anyway, in the example I gave earlier, the Garrison 212, clearly a dead-nuts size 6 line weight tested out at 36 cents which gives a line weight of 4.3, obviously not correct.  As mentioned by others, the deflection theory is correct, but the conversion from deflection weight to line size needs a major overhaul. The deflection weight/line size conversion table seems to be linear and it would be a simple matter to shift the scale upwards so that 36 cents equals line weight 6. As a practical matter, adding one line size the the present CC results would be in the right direction. This scale could be fine tuned if we had enough data from other sources.

        Incidentally, the action angle on my 212 is 56 degrees, slow, which seems about right.   (Bill Fink)

          Interesting result is when I shorten a rod by shortening stress curve with the stress values unchanged, the resulted deflection is less than original rod. (becomes faster) When I shorten a rod by copying the deflection angle, the resulted stress curve is higher than original rod. (becomes slower)

          I believe, when you shorten the stress curve leaving values unchanged, you are increasing the slope of the taper, therefore making it faster.  To achieve the same deflection   angle   in   a   shorter   rod   requires   less cross-section of bamboo, therefore, for a given line weight, there will be a greater dynamic bending moment making it feel slower.  (Al Baldauski)

    You stole my thunder. I just finished outlining the Common Cents method without mentioning its name which for some reason has become anathema to cane rodmakers. At the 2004 Catskill Gathering I set up a CC measurement booth which was TOTALLY ignored.  (Bill Fink)

      There was one set up by Darrol Groth at SRG too.  It was not well attended also.  I think it works well for making comparisons between not only tapers, but also materials.  For those interested, here is a link to the web site.  (Scott Grady)

        Why would you suppose that the results of tests like the 90 degrees or CC would be a function of materials?   (Bill Fink)

          I don't think it would be a function of the material.  What I think it is a way to compare the "action" of one rod to another rod.  You can compare a favorite graphite rod a client has to some of the bamboo rods you might want to show.  It is just another tool for comparison after the rod is made.  Its use in rod design would be a different thing.  (Scott Grady)

          Yes, you can calculate Youngs Modulus from them, if you think this information helps. the trouble is that we cannot control the basic material, or even evaluate it much before use.  (Robin Haywood)

      Darrol Groth did the same thing this year at the SRG.  Many of the newer rodmakers took their rods to them including myself.  My first, and one and only, rod tested out as a 3 wt using the common cents method.  I had it lined with a wf 5.  I then borrowed someone else's reel there that had several spools with various taper lines.  My rod cast a DT 4 well when there was 40+ feet of line out.  When we put a 3 wt on it did not load the rod adequately to control the line.  I'm not a good caster so I had someone who is do the testing.  I also didn't want to influence the outcome.  I found the experience enlightening regarding lining a rod but the outcome didn't make me confident in the system.

      It seemed to me that there is a flaw in the method in that all rods are measured only one way (either guides up or down, I don't remember which) and depending on the makers preference of spline positioning you would get very different measurements.

      Just my inexperienced observations.  (Ralph Tuttle)

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