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Now that you all have me looking and thinking about tapers I have another question for those experts out there. Since very few of the tapers in RodDNA have an action length entered other than 10”, has anyone experimented or given thought on how to define and or measure what defines the Action Length of a rod ? Does anyone care? (Ralph Tuttle) Where are you seeing 10" action length? I just took a quick peek at "models" and see various action lengths. They all look like they're about 10" less than the rod, so I would think they end at the grip? (Neil Savage) In RodDNA if you don’t enter an action length it defaults to 10 inches less than the rod length. If you look at a para 17 and then at one of the swelled butt rods or a ‘fast’ rod you would think that the action stops at some length other than 10 inches. Some designers are trying to increase the action of the rod by shortening the grip and reel seat by about 2” total. Other that like faster rods lengthen the rod and then add the swell earlier. Thus my question. (Ralph Tuttle) Generally, the "action length" of a given rod is defined as the rod length -10" (approximately the length of the grip and reel seat). This is due to the fact that those rod components generally do not have an effect of a given rods action. It is really up to to the rod designer as to what the action length is set to. I routinely set it to the rod length for convenience. (Larry Tusoni) Your question confused me since the action length is the rod length less 10" (approximately) and you asked why they were mostly all 10" action length. (Neil Savage) You're absolutely right. Poorly worded question on my part. What I meant to say is that the action length is defaulted to rod length less 10 inches. My question still stands. At what point is the action of a rod confined by the diameter/mass in the butt or thumb pressure or? (Ralph Tuttle)
Well, there seems to be a little hidden interest so I will continue... First, I don't think stress curves are the ultimate in rod design, or that Garrison Rods are great for me. Just so no-one thinks I'm a fawning Garrison addict. SC's are still a good tool to understand and the next step after just duplicating rods to understanding how rods work. Next, there will be homework...I don't know any other way to get stress curves across to anyone other than to say...You must own them..understand how they will work for you..It's always difficult for me to interpret what anyone else says about a rod. I must see the deflection graph to fit it into my own frame of reference. First, basics... I hope everyone knows that SC's are based on beam theory... You don’t have to go there, it's already in the math of the program. I will use Frank's hexrod form most of the examples... Everyone has access and it's easy to manipulate. I think it's time to give a big thank you to Wayne Cattanach... He developed the first software version based on the Garrison book... it was actually quite remarkable given the software tools available at the time. Anyway, Thank You Wayne. The inputs are known, but right away we run into problems... The first being action length... any guesses why? (Jerry Foster) Ummm....OK, I'll take a risk and raise my hand.....you need to determine how long is the grip and reel seat are going to be? (Marv Loopstra) Well, Here's my take on action length. I think the intention is to show the rod under it's fullest deflection. So, where do apply the power to make this cast. It is reasonable to assume that anything behind your hand isn't going to be involved in the bending action of the cast. So the reel seat is never a part of the equation to me. single handed rods here. Now I know this, any piece of bamboo no matter how thick will bend under enough load, so arbitrarily ruling out the bamboo under the grip doesn't make much sense either. So where is the point of power application. To me it is at the fulcrum point. I decided that was the mid point of my hand. The centerline of my wrist. roughly 2". so I use 6 " off the rod length as the action length. -4' reel seat-2" 1/2 for hand. I feel this allows for all the rod that wants to bend, to bend. Now for the proof, first go to hexrod and choose the 8'6" granger victory. Note the end dimensions .063-.375. now click on fundamentals and change the action length to 8' 0". click on hold constant stresses button... Next compute dimensions... Compare the dimension numbers. In only one case should the action length be at the top of the handle... That is for a wooden grip. And never ever should it be the full rod length. now experiment with your favorite rod/rods. move the action length around and see what changes in the dimensions. Now normally I would keep the dimension constant of course. But this exorcize shows that when designing rods from scratch the action length make a difference, and you will see if you now the dimensions constant the stress graph will change. The idea here is to get the best picture of the rod you can. Try it, get back to me (Jerry Foster) Some comments on action length. I agree with you that about the right place for it to end is the mid point of your hand. However, if one is just doing a Garrison style analysis where the rod doesn't bend, it's not of much interest. For a given point, only what's further out on the rod has any effect on the stress at that given point. The exercise you suggest in Hexrod muddies the waters. When one does as you suggested, Hexrod scales out the original stress curve to the new action length which must result in the new dimensions, but that's now a different rod. Apparently, an example of the rod was mike'd by somebody and submitted. Now they couldn't measure under the grip or reel seat, so they presumably said the action length is where their measurements ended. I doubt that Granger specified that. So stretching the stress curve in this context is to me a leap into the unknown. I note in passing that RodDNA doesn't fiddle with the stress curve when one changes the action length. I didn't mean to muddy the waters but to show why proper action length is important to a proper representation of the graph. If you wanted to get a better picture, I would extend the last given dimension all the way to the butt. Flat through the handle. As to the bending aspect, stress is bending, a rod which is not bending is not under stress, other than gravity. The reason I was using Franks is because I don't want to get into dueling software. I'm not sure I understand the part about stress at a given point. The whole rod is under the same force when you start to move it. (Well not true because the tip is accelerating faster than the butt during the rotary portion of the cast) If you change any part of the rod the entire stress/bend curve will change slightly. Not just a part above here, or below there... Al could chime in here, but it has to do with iteration. (Jerry Foster) I should state that I'm just trying to show how the ordinary maker can use stress curves. If you see the raw numbers, and can extrapolate the rod, or you use rate of change/slope, or you use stress, or you use deflection it is your decision. I have found on my rodmaking path that each of these conventions is an aid and they have been accumulative in terms of analyzing rod action. Using deflection was the hardest to get my tiny brain around because it was the biggest paradigm shift. You don't even care what the numbers are, you only care about how you want the rod to deflect/bend. (Jerry Foster) By ordinary, I meant makers like me. Those that aren't engineers, scientists, or mathematicians. I am aware you are all extraordinary rodmakers. (Jerry Foster) The part about the stress at a given point--If you are using just the Garrison analysis, at a given point, only loads further out towards the tip contribute to the stress at that given point. Hence there doesn't seem to be much point setting an action length. While the stress curve obtained that way does give you an idea of the flex of different sections of a rod under load, the calculations are done as if the rod didn't bend at all. (Mike McGuire) You might have figured out by this time that Mike is one of those mathematical people! (Tim Anderson) Mike is correct. Changing the action length alone will not change the calculated stress numbers, except to calculate them farther back toward the butt. One piece of hexrod trivia: If you have a rod with unequal sections, like a 7ft rod with a 4 ft tip and a 3 ft butt, you can trick hexrod into putting the ferrule in the right place by saying you have an 8ft rod with a 6.5 ft action length. On a more general note, I believe all the rod analysis and design tools can be useful, within their limits, to get the rod we want. Where all of them seem to fall short is at the ends of the rod. They don't tell us much about proper tip design. No one ever ponders the tip end of the stress or deflection graph. Same for the butt, especially when we add a swell. We all know how it dramatically changes the feel of a rod, but I don't think deflection analysis helps us understand it. I'm sure stress curves can't. Seems like we need a lot deeper knowledge of how a cane rod stores and releases energy to model the ends. (Frank Stetzer, Hexrod, Taper Archive, Rodmakers Archive) Yep Frank... absolutely true. Tips and butts are the most important, and least important part of rod design. And, no tool will design a rod for you. It's all about the known to the unknown. One must have some concept of the limits of stress that you and others can observe (feel), and then strike out from there. My basic formula is the 90% of the rod is in the middle 2/3rds. thats where the action can be changed and felt. The tip itself is the area from the high pt of the stress curve to the tip top. This is an uncontrollable part of the rod. What I mean is, you can set a tip dimension and control the height and length of the transition zone (turnover point), but from the high point going to the left on the graph the rod is trying to get to straight. We all can agree that the tip is at zero stress, which is no bend. There is certainly no bend under the tip top itself. so that first 5 to 20 inches or so is rapidly going from some max stress to zero as fast as it can. Or form max bend, lets say in the 1 degree range to Zero degrees, so unless you manipulate the numbers the rod will head for straight by the most economical means. (Jerry Foster) I may be putting my foot in it, but I do pay a good deal of attention to the last station or sometimes two at the tip. I have a theory that sharp stress peaks (within bounds) at the tip correlate with rods that will form tight loops without too much difficulty and protect light tippets. I do have to agree that they dodge the heavy work which I think you rightly attribute to the middle. This to me, is the region where smooth feeling rods have strength. A small rise in stress heading into the butt, in my mind gives the rod a second gear. What I mean is a slightly parabolic action. I like a bit of swell in the last station going into the butt to stop the action. Well, now, I think that I have exposed myself as a devote' of certain Payne rods. A great example of what I a speaking of is the Payne 200L (light tip). It is in Rod DNA. (Doug Easton) Your theory about tips and stress makes sense. I'm partial to a taper that has a two-humped stress curve, like the Cross Bataviakill in the archives. Maybe that is just because I am used to it. I do like some flex above the grip because I often pick the line off the water with a roll cast. Sort of the opposite of Robin's Superfast. (Frank Stetzer, Hexrod, Taper Archive, Rodmakers Archive) Good point Marv. And I'm wondering if thsat coulddoes go to a deeper issue of style and preference? I've cast rods that were very "tip casting" (?) and others that I could very much feel flexing in the grip! I like both in different situations, though I must say, to my tastes there's something very groovy about a rod that I can feel the action into my hand under normal, reasonable conditions. To Jerry Foster, I'm guessing I'm not the only one who's lurking and very interested in this subject. Please don't take silence for dis-interest! Speaking only for myself, those of you who are in the know on this immediately went graduate level. I very much appreciate your offer to start at the beginning. If you feel there are better tools than stress curves, please educate us newbies through stress curves and beyond!!I will say that I appreciate some of the nuances in the discussion so far, but I have no idea how to represent a stress curve, or any other graph, for a particular piece of bamboo. I'd love to see how to generate that graph based on the dimensions and to understand what the graph then represents in relation to that wonderful piece of grass in my hand! I think that a fantastic education in this would come from relating the graphs to the feel of varying actions, and I believe that I heard Jerry had a road show that did exactly that. A group of different rods that were similar enough to compare, but different enough in some basic ways that they did a nice job of demonstrating different actions and their relationship to their stress curves? Did I get that about right? Wish I'd been there to play with those. Absent your selected group of rods, I would like to be able to look at numbers for a bamboo rod and relate it to what I feel in my hand. At the different Rodmaker Gatherings there are plenty of classic rods that I'd love to compare my impressions with the curves, and I'm thinking that might just lead to a little more understanding. I'd appreciate any feedback from the group where I'm on track, or off base, and especially any education on this topic. Thank you! (John Jazwa) John, that is exactly what I hope to achieve in the next couple of steps... But step by step. Did you make your way to Hexrod? Do you need help? This goes for anyone. (Jerry Foster) I got ahead of myself for people new to this. What the Stress graphs show is the internal stress of a rod with a given amount of power in the form of 4 G's of acceleration and a resistive load of the length line to be cast. (Line fished). Plus, some other variable that aren't that important at the moment. The resultant stress in inch 0z2 results in making the rod bend. So the chart, as I will show later, is also a deflection graph. Now for the sake of argument, my contention is that the shaft bending is what you feel when you cast. Or the rod foreshortening, getting shorter as it bends relative to your hand. Individual rod preference is derived from what you feel, feedback, when you cast a rod. So this chart will eventually, I hope, let you discern the rods you like, or may not like, from the picture you see of the rod deflection profile. It is also useful in rod design by the same criteria. So we have this tapered bamboo stick with some line hanging off the tip that I am going to set in motion. What I feel will determine whether I like the rod or not. I my parlance, whether the rod likes you or not. This is all determined by your unique casting style. There are very few really bad tapers, so the idea is to match the rod/rods you like to their graphs. This gives you a visualization of what you like and you don't have to just ponder the numbers (taper). Is that a good start? (Jerry Foster) Trying to read and digest 39 emails on this subject is what has kept me from jumping in sooner. I am still rather new to this. Rod #1 was completed 1/2010; rod #30 is waiting for polishing. I use Larry Tusoni's Designer program and am very reliant on stress curves to come up with a design I want to build. Until reading these recent emails I assumed that the "bumps" in a "famous" maker's taper was due to measuring or production errors but someone, I believe it was Rob Smith, said that some of these bumps were intentionally made for a specific effect. Then I looked at the stress curve of Bob Nunley's much discussed rod and knew that these bumps were intentional because the taper came from designer and not someone trying to measure another's finished rod. So I am trying to get a better understanding of their purpose. The first 15" of this rod are rather thick but the delta between stations drops significantly from .022 to .012 at stn 20 and 25 then jumps back to .020. My initial thought is that the first 15" are stiffer than usual to help keep the loop tight and that the drop in deltas provides a cushion so that the tippet doesn't break on a hard strike. Any comments would be welcome. (JW Healy) BTW - I now know the answer. The rod in question is Nunley's Snake Rod. The taper was published on the List. I spoke to Nunley at 2013 SRG and he said that he wanted a rod that would be good for very short casts with a gentle stroke and good for longer casts with a full casting stroke. The hinge at 20" is for the short casts. It allows the rod to flex primarily in the top 20 inches. With a full stroke the rod flexes much like a parabolic taper. (JW Healy) Yeah, I struggle mightily with the bumps too, especially as I can never get their originaters to explain them in a way I can accept. remarks like "Well, it works”, or "It seemed to make a difference" and other such inquantifiable observations have no place in the design of anything. Action lengths, well, yes, normally and in most good rods the action should start at the top of the handle, lower down is a bit eccentric, although, of course, if you stress any rod enough you will create a bend under the corks, albeit not much of one. The weazel in the rabbit warren is the rods whose action starts significantly above the handle, sometimes by several feet. This is what Ritz was after by the rods named parabolic, and may I say again that its just a trade name, likeSuperfast, and just as misleading. Unfortunately, Ritz was a hotelier and not a rod designer and neither, on the evidence of my eyes was Pierre Plantet, the rod designer for Pezon et Michel.Perhaps he just decided on the ring spacing. the fundamental error was made because the solution is a bit counter intuitive. Most people, if asked to put the action part of the rod three feet up would create a large diameter, probably untapered butt. It would be a rod on an extension pole they would say, indeed, I’ve heard them say it. their next observation was usually that it did'nt make a very nice rod, they were right! The limitations of the material, in this case cane made the rod heavy and bulky, and P&M took to glass butts for the later rods, with little more sucess. The solution. In fact, is to make a butt as fast tapered as you can, hollow built too. Whatever you do the thing will bend, but its better to have do that up where its bending anyway and not just above the handle, which is what happens on any rod whose tapers are slower than those needed to create a proper quarter circle when bent so the tip is at right angles to the butt. Iam not saying this is the right or wrong taper, its just an illustration. The trouble is, if you make one of these rods, as I have (I call them "Proper Parabolics.................") they are still not nice rods. They should be, the tip tapers are correct and complete, not truncated like the Ritz ones, by which I mean they haven’t been shortened at the bottom end, but, somehow, you can never seem to get the timing right. They cast adequately with about three line sizes and well with none. It’s not even my opinion that they keep the line especially high or fast either, certainly no more than a fastish rod with a Gould figure of about 340. If anyone wants to analyse the tapers of this rod and give me their views, I'll break with the habits of a lifetime and put the tapers on public display for you. (Robin Haywood) My analogy for looking at stress curves is to picture a 7ft long tapered torque wrench. If you pull on it slowly you will feel the points in the taper that a yield the easiest and those that are stiffer. Thats exactly what the stress graph is showing. The problem is of course the casting motion only takes about 1 second so you have to develop a quick sense of feel. But in most cases your overall impression of whether you like it or not is sufficient. You must use, or develop your own judgement protocol. Robin... I'm not sure if your making a statement about action length or not, but my point was the rod will bend by the numbers a deeply into the handle as the cane and the force will allow. To arbitrarily truncate the stress curve input distorts stress curve. (Jerry Foster) Jerry this analogy makes perfect sense to me. Where you place your hand on the wrench will impact the stress points. ie action length. Thanks this helps a bunch. (Ken Weymouth) I'm afraid you've lost me Jerry, I’m much stupeder than I sound. Would you mind having another go at it please? (Robin Haywood) Hehee, you can't pull that "Oh woe is me" crap here.. I think you are looking at rods with a developer’s eye, I I'm trying to explain how stress curves work from a post developed rod, analytical viewpoint. If I really need to elaborate a point...please be specific. (Jerry Foster) I guess it's time for a note about measured rods and craftsmanship... Since Garrison, all rods have been measured on 5" intervals... hopefully with the rod assembled, starting at the tip. Most of the rods we are looking at were made on Mills/bevelers using a taper board, or form. Although typically the numbers on these were set at 3" or 6" they were filed to have a nice smooth surface for the cam follower to ride on. Because the math we use wants to generate a straight line between any two points we will see small zig zags in the stress graph. Most of these are inconsequential. Moreover, most of these rods were measured over varnish and of course not over wraps. So they are close to the originals, but not exact. Does it matter, probably not. And speaking of action length, when you change the action length and try to keep the stress constant you will notice that the math tries to predict the numbers for the rod based on the given trajectory. This probably isn't correct, but it is irrelivant. The issue to me is you can never get a really accurate stress graph when the rod has been originally entered with the action length set at the top of the handle. But this is purest crap and doesn't really matter. Now in terms of accuracy of your own rodmaking. I always strive for perfection. Never attained, never will, but that is the intent. To this end it takes quite a deviation for more than a single station to create a noticeable difference between that and a rod that is on the numbers. So don't worry about small deviations from the taper. Just try to do better next time. (Jerry Foster) Yes, a big THANK YOU to Wayne, for HEXROD, and a lot, lot, more!Okay, Action Length...the way I always understood it, was Wayne often said that the action of the rod stops at approximately at the top of the grip, so the action length, was about 10" less than the rod length.However, I've always wondered why that is. It seems that a cork grip is flexible enough to not dramatically affect the action.Help!!!!! (Mike Biondo) I've heard Wayne and others talking about the action is stopped by a swelled but... Experiment with one. A swell certainly curtails the action but the stresses don't go to 0, so there is still a little bend there. But if you also noticed a lot of the numbers move around when you move the action length which shows the rod doesn't just work in pieces but the overall stress of the rod is impacted (is that a word?). (Jerry Foster) Jerry, would you please comment on the variable "tip impact multiplier" in the Hexrod design parameters. What is it supposed to capture or emulate? It certainly impacts the dimensions of the design if changed. (Ken Weymouth) Jerry looking at the stress curves of the granger victory rod, I see an increase in the stress of the rod at 65" created by the minimal increase in dimension of .003 from the prior station. Would this be considered a "hinge". I would have thought so until recent discussions, but now I am not sure but whatever it is called what do you believe its' intended purpose is? (Ken Weymouth) The stress peak at 65 is a result of a relative reduction in the rate of change at that point. My guess it is to compensate for the stiffening effect of the ferrule. This happens more slightly at the other ferrule too. I don’t think it would have a hinge effect in that position. (Stephen Dugmore) It may also have to do with wanting to use a smaller (and lighter) ferrule – probably both (Stephen Dugmore) Interesting, I will go back and look with a new set of eyes, Thanks Stephen. (Key Weymouth) Question open to all - What defines a hinge in your mind? And what is its' purpose. I have heard roll casting ability. What other casting attributes would it have? (Key Weymouth) Hopefully this question will add to the discussion. In casting we all strive for a tight loop which requires the tip of the rod to track in a straight line. It would seem to me that the more the rod deflects the more skillfull a caster would need to be to maintain that straight tip movement. Stiffer rods would bend less and perhaps would be easier to cast. Parabolics would probably have a sweet spot depending on how close to the tip the "hinge" is but to really load would require some adjustment in the casting stroke. Does this logic hold any water or does it help to explain why you personally might like one taper over another? (Ron Kubica) In my mind, a hinge is a point on a rod where the rate of change in the taper (the delta between stations) decreases and then increases sufficiently to create a flex point so that the rod will bend there more than above or below that point. Cattanach put that point about 2/3 down from the tip to improve the rod's roll casting and that works very well. I am not sure what putting a hinge anywhere else will do to improve the rod and hope someone else can explain. (JW Healy) It will make the roll casting easier, I grant you, but at serious cost to the rods other functions.Also, how difficult is roll casting anyway?And when it is its for short range fishing, so chop the taper off a line one or two grades higher and use that. It even works better, as the end floats better, being thicker. (Robin Haywood) OK. Pls help me understand - what other functions of the rod are going to be impaired? (JW Healy)
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