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I’ve come up with a question I can't answer for myself. And I hope some of you can bring a little light in the dark. Is there a rule of thumb for the tip diameter regarding to the line weight ? Lets say: 0.059 inch at the 0 Station for a 2 wt. If I compare my taper archive this numbers comes out when i take the average for certain line weights. But when I look at the maximum and minimum values there are also great differences from one rod to the other. Any suggestions or theories?? (Markus Rohrbach) I think that if you are building straight tapered rods, you will find that you can have such rules of thumb. There was a wonderful post back in the archives in which AJ Thramer discussed how classic rodmakers would determine a rod's line weight by ferrule and tip size. Also in the Wise Fisherman's Almanac there are suggestions for tip size and rate of change for every 6". So, yes they work for straight tapered rods. BUT, most parabolic actioned rods will be thicker in the tip and throw off the theory. Not all taper schools will be so easily fit into these sort of "rules of thumb." Interesting to hear what others have to say. (Bob Maulucci) There is no correlation between these two parameters, but for various reasons, none of them very good ones, you might find some correlation between line weight and the diameter about 10'' back from the tip! (Robin Haywood) Darryl Hayashida had a theory that the last 10 inches of the rod were critical in determining whether the rod will cast a tight loop or not. If you search the archives for "Tight Loop Tip" in December 1998 you will see the posts. Some people disagreed, of course. (Frank Stetzer, Hexrod, Taper Archive, Rodmakers Archive) I think that the first 5 t0 6 feet holding the rod is critical to forming a tight loop. (Ted Knott) No doubt about that, but everything else being equal you can change a tip configuration to cast a tighter or wider loop. (Darryl Hayashida) I still make my dry fly rods with that tip configuration, seems to me to add to the accuracy of a cast, but if I am interpreting the question right, the diameter at the zero station is of very little consequence. That particular part of the rod is going to be inside the tube of the tip top guide anyway. The only other consideration I would pay attention to is that for heavier lines that means the rod will be used to go after bigger fish, so the tip should be thicker to handle the stress of fighting a heavier fish. (Darryl Hayashida) Thanks so far for your information. One reason for the question is, is there another starting point to recalculate the taper than add or subtract 0.005" at each station to change for one line size. Or in other words, if you design a new taper (lets say a 4 wt.), where do you start? I wrote about the rise or slope of a rod taper that can characterize a rod (fast, slow one or somewhere between). But at this point I have to decide where I want to start draw the line and this point is the 0 Station of the taper. (Markus Rohrbach) It's a design concept and can be adapted to any rod design. The easiest way to understand it is through stress curves. Look at the stress curve of the Cattanach 7' 4 weight at the RODMAKERS site. Go to Tapers, Wayne Cattanach, catt7042. See the way the stress curve makes a sharp peak at the 10 in. station. If you follow that concept, only you make the sharp peak top out at the 5 in. station that tip will throw a tighter loop. On the other end of the spectrum look at the stress curve of the Orvis Battenkill. You will see that the tip stress curve is flattened out with no sharp peak. This is a lot slower rod, but just looking at the first 10 or 15 inches of the tip, if you had put this tip design on the catt7042 and casting the same, you will throw a lot wider loop. This isn't saying that the Battenkill will never throw a tight loop. A person practicing enough with the Battenkill with the intention of casting a tight loop will be able to compensate and cast a tight loop. What I am saying is with everything else being equal - including casting stroke - a tip design like the catt7042 will cast a tighter loop than a tip design like the Orvis Battenkill. (Darryl Hayashida) I think the two stress curves opened my eyes. If the tip is heavy over the first 5 -10 inches the bend of the rod is only moderate at this position and the rod will throw a more open loop than with a lighter tip that will bend more. Is this correct? (Markus Rohrbach) The Common Cents line-weight-measuring scheme (rejected by cane rodmakers for some reason - don't we want the truth?) makes it very clear that the last few tip station dimensions dictate rod performance more than intuition would suspect. (Bill Fink) That’s clear, but how would you describe the characteristic and performance of two rods without casting? (Markus Rohrbach) I too had looked at this and came up with values very close to yours as follows; 4 wt 0.0685 The rest of the line sizes had too few rods to get a valid number. However if you take the 5 wt diameter at 1 inch, which is where I start so that I can plot and calculate values for this point, and use a constant value increase per station of 0.0135" and plug this into Hexrod, you come up with a very usable one piece Straight Line Taper using a 5 wt line weight of 420 grains and a length of line of 50 feet. This stress curve I use as a standard for comparing all other 5 wt Rods. Further I use this stress curve to establish the tip values for the other line sizes, as follows; Stress at each station held constant. 3 wt 64.5 If you use the 5 wt taper in Hexrod and then change the line size you will come up with these values and the SLT for a one piece rod for each line size. I use a one piece rod so that the ferrule does not add to the stress curve and distort it. If you tell me the rods you are comparing I will send you the graph for you to look at, all you need is MS Excel to view it. (Bob Norwood)
Just been thinking how crucial the first 5 inches of the rod are (especially for light line rods) and yet this is the one area where stress curves give little info. I generally make my tips about 3 inches too long. When bending a tip section by hand before final cutting to length the difference in the curve when pushing down on the very end and at 1 inch intervals below that is striking. This would have to have a noticeable effect on the rod’s performance including on tip bounce. I recall someone commenting about a rodmaker who designs by planning and bending strips until the curve looks right. Makes sense. (Steve Dugmore) Once, in a talk I gave, I pointed out that the only correct tip dimension was zero, and the problem we therefore had was planing strips to half of zero. This was supposed to be a joke, but as nearly all of you know, my jokes tend to be a little too dry for most audiences. On this occasion someone got all your own backs for you, he asked me what the correct dimension should be at a point an infinitely small distance nearer to the butt.I asked for that.Most of the so-called classical makers, on either side of the atlantic, had a minimum tip dimension, this was governed by the hardware available to them and their view on how thin they could go without constantly having to make new tips under warranty. For some its 65 thou, others 78, Chapmans about 88.............And I don't blame them at all, its why I don't usually make rods for people and nobody ever has or will get any sort of guarantee, except one for delamination. The world is full of hapless clods, like me, I regularly break rods. The dimesion 5" up from the tip is the one to worry about, nobody will notice if the last 5" is flat or not, but they might if the last ten inches is, and people like me will giggle at you iof the last 15" is. So seventies "guess and hope".Those rods had rigid butts, too, in fact, only the bottom 2/3rds of the tip bent at all, the rest was always straight, you find the problem on a lot of Bruce and Walker carbon, every Dickerson I've built, and a lot of Harrison carbon, too. Its an easy trap to fall into, I would know, I fell into half of it quite recently, the butt half. The only reason the tip was OK was that I was making the thing for myself, if I had to sell it the tip would need beefing up and, PRESTO! I've re-invented Dickersons tapers. Such is the bizarre nature of life that these rods can cast rather well, except that very often you think they cast no line preferentially, but all of them adequately, just. They play fish well enough, but so does nearly anything within extremes of slow/fast taper.Lastly, and you were all waiting for this, I’m sure, messing about planing things up until they "look right" is the design philosophy of the imbecile. It is quicker, and much more effective to do a little basic arithmetic and employ a bit of graph paper, you don't even need a computer, its only marginally faster. As a golden rule keep the rate of taper of the last 25/33% back from the tip faster than the bit immediately below it and you will never go wrong. (Robin Haywood) You are probably correct that it is the 5” station that is critical – my pressing on the tip which is 3 inches longer than it should be is probably leveraging (can you say that?) the 5” station. However, I am certain that if you make the first 3 or 4 inches too thin you will have problems and you will change the way the tip performs. Don’t get me wrong, I am all for graphing. Stress curves, slt’s, deflections genomes etc. are all great, but having designed and then bent a few tips to look at how the predicted and actual physical deflection looks, I can certainly see how someone could design a rod from the actual physical deflection if they were that way inclined. I think your advocating against a ‘look right’ design approach is, as you say, to be expected. So is your crudely (and of course rudely) labelling such an approach as imbecilic. That in particular does not really help, no. (Stephen Dugmore) Well, how do you design an aeroplane these days? Do you assemble a lot of skilled metalworkers and tell them to make something that looks right, or do you assemble a load of qualified structural engineers and ask them to design something that is extremely unlikely to fall out of the sky unasked? The penalties for mistake in your decision may be very different, but the principle is exactly the same, isn’t it? The thing has to say up and keep on staying up.Rod tips. very, very early in the flexing process the last 5" becomes straight, and therefore under zero stress. If it is much heavier than necessary it may, aided or not by the material below it, contribute to an increasing tendency to "tip-bounce". I put that in inverted commas because I hold the view that a lot of tip bounce is caused by operator error.Cane is worse than glass or carbon, but better than greenheart in this context, its simply a stiffness to weight ratio issue. But casting like a cow handling a musket really brings the condition to the fore! Mainly, it is most noticeable when someone tries to make a very slow tapered rod cast any sort of distance. I have a Hardy Gold Medal here which can be made to demostrate the problem at will. There is nothing wrong with the rod at all, used for that which it was designed, but sadly we just don't do it like that any more. If simple sums and graph paper actually do intimidate anybody these days, and I might find that rather hard to believe, then a giant whiteboard erected on one wall of the workshop may suffice, I suppose. I did, once, do this, because I wanted to try and understand the correlation between the actual tapers and the degree of deflection for either a common load or a common deflection level (i used two, the quarter circle, and the point where the tip is at right angles to the butt, the latter was more consistent). Since I thought that Ihad been guessing up to that point I was somewhat amazed to discover that the correlation was quite near enough for practical purposes. The reason I was unhappy was that I was, and always do, use compound tapers, and I thought that this might make it more difficult to alter the length or stiffness whilst retaining the same curve. You can retain the curve OK, but the rod feels different. As a guide, if you lengthen a design it will feel slower, and if you shorten it, faster. Amusingly the crude Gould system brings this out perfectly, and if you elaborate the gould system so that the measured distance becomes proportional to the rod length all, you do is make more calculations for yourself, the difference is hardly worth the bother of doing the work.Designing something on the principle of if it looks right it probably is requires you to be able to actually see it. You can't see a rod taper, merely form an opinion on the relationship between the tip and butt diameters for the (estimated) length, this is useless. Ask ten people how long a rod is and you will get ten answers, probably all wrong. Even when you can very clearly see it, like a lump of Doxford diesel engine in a ship, you can certainly decide whether its big enough, but is it too big, and by how much? If you make the top five inches of a tip too thin or flexible all that will happen is that the load will be passed back to the area below it sooner and therefore the effective length of the rod will be reduced csooner. And the battle curve when you are playing a fish may look a little prettier, but you'll still land it, probably.As i keep saying, go into hexrod, punch in constant stress figures and look at the curve, its all you need to know, to start. Then simplify, and you get three zones, top third fast, middle third slower, bottom third fast again. The secret of rod design in one sentence? Hardly! Is it thirds, or 25/45/30? Or some other combination? Is the rate of taper at the tip faster than the butt taper or slower? And, anyway, what rates of taper should we choose?Depends what you want the rod to do. Perhaps you can now see why guessing and hoping won't work, nobody has enough lifetime left. What you do is this, and this really is the short cut. Take a rod you like which is as near to being ideal for the job at hand as possible. Measure it, you need to know if its hollow built, and if its carbon then you've introduced another three pages of learning curve, but mike the thing anyway, and graph it out. Now you know what the taper looks like, in compressed form, decide which bit to alter first, and why. You only alter one bit at a time, basic scientific experiment rules. Make the thing, not beautifully, just so you can use it, tape keeps rings and reels on perfectly well. Duplon handles are wonderful. Keep modifying, and keep learning.By and large the tip is more important than the butt, on average I get the butt right the second time, and some of my rods have more tips than a porcupine. There is a lot to be said for a few alternative tips, but don't tell any rod designers I said that, its the purism, y’know. (Robin Haywood) I've been mulling over this 5" thing. One... sticking a rod against something and pushing it is not a valid test of anything real. It does make the bamboo bend but has nothing to do with the way it deflects under the stress of casting.Yes, the 3-7" area will noticeable take a jog on some rods. You might consider this is a natural correction made by the cane when the tip dimension is not a normal path for the rod to straighten (bend). I'm not sure whether this is a good or bad thing. Rods seem to work fine either way. We (myself included) often make a decision about the size of the tip without any consideration of how the rest of the rod will react to meet this demand. Things are very subtile at the tip, but not critical. The tendency is to make the tip too slim and then find that at distance the rod will not turn the fly over.Robin, I've asked several times if you would tell us about the quarter circle thing. I must proclaim ignorance. Surely you don't intend for the rod to be at a 45 deg bend angle, or the tip to point 90 deg, or that the rod must bend in a specific arc? Do you? (Jerry Foster) I was hoping you might have something to say.I have to disagree that bending a rod statically is without merit. It certainly is not scientific (!) but does tell you a whole lot about the rod, no less than simply looking at a deflection graph (without referring to the figures).I am not sure what you mean by " 3-7" area will noticeable take a jog on some rods. You might consider this is a natural correction made by the cane when the tip dimension is not a normal path for the rod to straighten (bend)”?When you consider the amount of impact a tiptop has on the rods performance surely it stands to reason extra cane in the first 5" would have an impact too albeit less dramatic perhaps? Likewise, too little cane I am convinced sets up a floppiness (another scientific word there for you and Robin :)) that registers negatively in the cast. (Stephen Dugmore) I guess I missed my point. The entire left side of the slope, from the high point of the stress curve is set by the values at the high point in the curve (transition zone) and the size of the tip top. The individual reading along that slope should be a sequential sequence. If you alter that, you are going to put a jog in the tip.Are you picking 5" because that is the first point you can impact if you use planing bars?I should have said, pushing the tip against a surface shows me nothing about the rod, except it bends. Others, like yourself seem to derive more from it. How do you teach someone else what it means? (Jerry Foster)
I'm restoring an 8' bamboo rod without any signatures, ID numbers, etc. It's probably not worth spending the time on, but it casts great and I want to learn how to restore bamboo rods so I'm going to proceed. I want to fish the rod. The top four inches of one of the tips has a flaw in one of the joints. It's not delaminated, it just has a visible line down one side to the first guide. I would like to cut the rod off at the first snake guide and place a new tip where the guide is. Will this effect the rod's action? Should I leave it as is? Please help. Thanks. (Rick Satchwell) Someone else may want to kick in here, but right off the bat I'd say you'd probably stiffen the tip section noticeably. The thickness at the first guide (usually 4-4.5" from tip top, you don't say) can be 10 thou thicker, give or take, depending on taper design. Some tapers have very little difference in the last bit, others a great deal. If the open glue line is right under a guide, well, I'd also say that's the very best place to put a glue line. The wraps should help some to hold off disaster as well as the guide itself stiffening and bracing the area. You may want to reconsider cutting and just put a new guide and wraps back in the same place and fish it. (Bob Brockett) Don't cut it off, put a clear repair wrap over it to reinforce it. If you cut it off it will affect the action. It could just be a glue line or slight gap that has opened up, in which case the reinforcement provided by an overwrap will most likely keep it from getting worse while you fish with it. (Bill Walters) Thanks for the replies. The flaw is 4.22" long and starts at the tip. The center of the first guide from tip is 4.44". If I cut out the flaw, the rod diameter will be .114" at the base of the rod tip. I'm interested in knowing how the rod will be effected if I cut it off. Will is shorten my casting length? Will it kill the rods action? Does it effect the line size? etc. Thanks. (Rick Satchwell) It will probably deaden the action of the rod some and could require you go up a line weight just to get it to flex a little better. Use an overwrap of white silk and then hit it with some thinned flex coat epoxy to make it go clear. To give you an idea of how off that .114" is, the largest I've ever seen a trout rod start at, is in the neighborhood of .085 -.092. If it breaks after doing a reinforcment wrap, you're not out much, but if it doesn't it will undoubtedly fish a bit better than if you removed that area. (Bill Walters) I live in Central Illinois and there are very few trout to be found. I will mostly warm water fish this rod. I’m hearing that its best to leave the flaw and fish until it breaks. The flaw probably explains why there were three intermediate wraps between tiptop and first snake guide. I’m thinking that I’ll just replace the inters and fish it until its breaks. If it breaks, I’ll turn it into a great bass rod! (Rick Satchwell) I'm handicapped not seeing the actual rod section, but you might also consider mixing up your favorite rod epoxy (what you'd glue the blank with) and working that into the gap. Then hit it with just enough heat gun time to liquify the epoxy and cause it to go where no man has gone before(!) Wrap it closely but not necessarily perfectly with thread, let it cure, and sand the thread off. The white silk wrap is the time-honored reinforcement, but I've repaired greenstick tip fractures as I describe and NOT put on the white silk overwrap, and had them perform (and last) just fine. Of course, I don't think you hurt anything by applying the white silk AFTER you've glued/squeezed the gap as much as possible and the epoxy has cured. Belt-and-suspenders, if you will. (Steve Yasgur) You can also just replace the bad spline by scraping it out with a snap blade knife. The blade tip is 60 degrees so it works fine. Just remove the closest wrap and work from there to the tip. Slowly scrap out the spline to the glue lines on both sides. It should only take about an hour to scrap the spline out. Then just replace that spline with a new one and glue it up again. When you rewrap the guide it hides the joint and gives it strength too and you should retain the same rod action and be totally invisible. (Ken Paterson)
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