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Rod Design - Duplicating Actions

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I've got a question about taper design: How would you go about duplicating the action of a rod that you could not mic?

Say it's a rod that you only cast once or a rod that you regretfully sold or that belongs to a friend who won't let you mic it or, heaven forbid, was made from graphite or fiberglass or is some dream rod you have in your head. All or any of the above scenarios, it doesn't matter. The point is that you know how the rod feels in hand and you have some idea about the shape of the rod bend/curve under stress. How would you approach designing the rod? (Especially if you didn't have another rod close in action to tweak.)  (Jim Lowe)

Hmmm...  If it were me, I think I'd start with a linear taper to approximate the general action speed, line wt., etc., and tweak from there.  Would take a few iterations to nail it "exactly" (at least as close as you could probably come, working in the dark), but certainly possible, and probably an interesting exercise...  (Todd Enders)

Three possible scenarios:

1. Write the taper in the way you think will approach at the one you are dreaming. When you feel a rod your mind is far away of that feeling, they are deep into your heart try that the numbers came from there. Usually you have to be very fortunate to get the rod but sometimes happen.

2. Make five alternatives, and them make the fine tuning to get the rod you want.

3. Don't let that rod go before you mic it in every aspect.  (Marcelo Calviello)

Start with making a rod as close to what you think you want. Perhaps a fast rod with a stiffer butt section, or your dream rod has a parabolic action, or you know you like a slower action, etc. Make the blank for a heavier line weight than what you want to end up with. When you have the blank made tape the guides and reel on, wrap a rag around for a handle, and cast it with the heavier line.

Determine what it is you need to change - maybe the butt section is too stiff, the tip is too tippy, whatever it is, then take off all the taped on hardware and using a sanding block and some fairly coarse sandpaper (220 or 320) sand down the diameter to get what you are looking for. If the rod is too tippy, try shortening the tip by a couple inches. Butt too stiff - sand off a few thousands. Midsection too loose - sand off a few thousandths on the butt and the tip making the mid relatively larger, etc. This rod is not going to be the final product, you are just using it to determine the taper. You might end up sanding off a lot as you experiment, hence the reason for starting out with a blank made for a heavier line. Sanding down a sacrificial blank to find your action is a lot easier than making a half dozen or so blanks, tweaking each one a bit as you go.

When you find your perfect action, mic it, and you are all set.  (Darryl Hayashida)

Bravo Darryl,

Best approach to perfection I've ever heard.   (Bill Fink)

I would like to recommend the steps of Hayashida but originally starting with an INSIDE-OUT built rod blank. In that configuration you may sand the surface safely as you want without losing the power fibers which are now inside the rod - see this web page.  (Tapani Salmi)

If the power fibers are inside, then they are in the neutral are of the stresses and the results will not be the same as when they are on the outside and subject to the compression and elongation stresses. I'm not an engineer, but I think that describes the concept of a flexed beam. Putting power fibers on the inside was done over 100 years ago when split cane rods were being smoothed off round to emulate the wooden rods of the time. The technique didn't last very long.  (Steve Weiss)

Actually, some could be inside and some out, as you could wouldn't have to put the power fibers at the apex of the triangle. If the strips are planed out in the usual fashion then you could have the power fiber side of the strip oriented radially.  (Henry Mitchell)

But that wouldn't give you all the power fibers at the "flange" of the beam.  You would still be placing power fibers in the "web", where they would be contributing less and less the closer they get to the center of the "web."  The closer you get to the center of the "web" in the beam, the amount of compressive and tensile stress goes to zero.  That's why the call it the neutral axis of the beam.  Why would you want to put your strongest material closer to the area that sees no stress, and put your weakest material closer to the area that sees the most stress?  You will change the amount of stress that beam called a fishin' pole will be able to take.  (Mark Wendt)

As long as there is no pith in your strip (my "mega flaming" method burns away all of the pith), sanding away the "power fibers" (the smaller fibers just under the enamel) makes very little difference. Before you start slamming me for that statement, try it yourself. I have actually tuned rods by sanding away the outside and it works.

As for the people who tried to sand the rods round, it was more a matter of they found it didn't make much difference, so why go through the extra work.  (Darryl Hayashida)

I understand that, I was just trying to point out that they wouldn't all be at their most noncontributory point either. And as you get nearer the tip does this all become more academic (like it hadn't already?) where there is a greater percentage of power fibers to pith?  (Henry Mitchell)

But why take away the most contributory fibers from the place where they would do the most good, ie the furthest point away from the neutral axis of the beam, and place them closer to the neutral axis where they are doing little to no work, and contributing little to no strength to the beam (rod)?  True, there is a greater percentage of power fiber to pith out near the tip, but consider there is still pith, and the power fiber is the most densest on the outer side.  I'd still prefer, from a purely engineering standpoint, of concentrating my load bearing material further from the neutral axis, whether it's at the butt end of the rod or the tip end.  You of course, are free to make your rods any way you prefer.  (Mark Wendt)

After making some rods with inside-out configuration I only can tell my experiences: the difference between an inside-out and  traditional rod is minimal. You certainly may use that structure for modeling the taper and the action of the rod - which was the original problem! Perhaps there is no a clear-cut neutral axis in a split cane rod or the modeling should be more complex than a simple "beam". I do not recommend to build some poor functioning rods (I myself prefer hollow building) but suggest an experiment with possibility to safely sand the rod surface without losing the holy power fibers.  (Tapani Salmi)

Maybe so for the modeling, but if I was really after a certain taper and action, I think I would still want to make it the normal way, at least the last version of the test rod.  A beam is a beam is a beam in bending, whether it's a cantilever, a simple beam, or a fishing rod made out of grass.  Compression and tension can be measured statically and dynamically, and the load the beam can handle can be predicted.  Garrison proved that with all his calculations, as does Hexrod, RodDNA, and other programs for measuring stress curves.  The only unknown factor in the equation is the person casting the fly rod, but, while that's a large factor in how the rod "feels", it's not much of a factor in determining the  stress curve of the rod, or the action of the rod.  Maybe a better way of designing a taper is to use some kind of glue that can be broken down easy  when you want it to, and to replane the taper at certain points to "tweak" it, then reglue it.  (Mark Wendt)

You could go to one of the gatherings and cast the rods that are graciously put out for all to cast. Keep trying rods till you find one with the feel you are looking for, or at least close to it. You may find one you like even better. Then run it through one of the computer programs, online web sites, or spreadsheets to "tweak" the action.

A suggestion, write down the rods you like and why. I have found with so many rods, the memory tends to blur after a while.

This is a much more fun way.  (Rich Jezioro)

I have been very interested in your request on how to design a rod that you have only cast but do not know the taper design. Since you have had no direct offers about how to do the design, I would like to design the rod for you, but I need a little information first.

1. Rod length and number of pieces
2. line size.
3. A very accurate description of the rod action from tip to butt.

Of course any additional information you can supply could be useful as well.  (Bob Norwood)

I have been wondering for some time now, has anyone ever taken a taper from a plastic rod and converted it to cane?  If so what were the results?

I assume the characteristics of the two different material are so different that it wouldn't work well but I know nothing about the graphite and only a little more about cane.

If someone would respond to this issue I would appreciate it.  (Dick Steinbach)

I know of only one case, and if truth be known, the story might be aprocrophal.  When rods were being considered for the "River Runs Through It" Montagues were the first selection.  Thomas and Thomas redid and furnished some rods to the production.  The casters didn't like them because they were too slow to perform the acrobatics of line handling required.  Walton Powell had just acquired the right to manufacture Hexagraph rods in the Us.  and made up a few Hexagraphs to the Montague taper.  The rods were in my opinion an abomination.  I felt like I was casting a 2 x 4 stud. when I fished with one of them on DuPuys Creek.  Really I think the shoe is on backward.  Are not the plastic guys trying to give you the feel of bamboo?  (Ralph Moon)

Yes I have. The first "good" fly rod I owned was the Orvis Far & Fine. It's a 7'9" 5 wt. I tried to duplicate it in bamboo. I measured it, graphed the stress curved and tweaked it to be a 5 wt, still preserving the overall shape of the stress curve.

It's an okay taper, but the feel of the rod isn't the same as the graphite version. Graphite is too much lighter than bamboo and the overall inertia of moving the rod back and forth makes the bamboo version feel a lot different than the graphite. No way can bamboo duplicate graphite. I kind of like it that way.  (Darryl Hayashida)

Carbon rod tapers can have both inside and outside diameter variations, along with the use of a variety of material types along the length of a rod. The mandrels on which the carbon cloth is wrapped may have a linear taper, but may also have a convex taper. When the carbon cloth is wrapped on the mandrel, the mandrel must be "pulled" from the final rod section after it is cooked in an oven,  so either a linear or convex mandrel taper is used. A carbon rod is usually "machined" on the outside to provide a smooth surface (old Orvis carbon fiber rods had the shrink wrapping left on the outside of the rod). So, it is probably not very easy to convert a carbon fiber rod to a solid or hollowed out bamboo rod based on geometry.  (Frank Paul)

I've noticed a few comments recently, and in the past, on this list about improved versions of classic tapers. Would someone kindly explain to me how you'd go about improving a  Garrison, Dickerson, PHY, or any other of the classic tapers. I understand how you might change such a taper,  but how would you improve it? How about the Payne 98? I thought the one I built which was taken from original specs was the best one I'd ever cast.   (Jim Bureau)

You know, this question comes up fairly regularly on the list and goes directly to the question, "at what point has a taper changed enough to be considered new, or improved"? How many thousandths at how many stations does it take? Has a majority of the rodmaking community ever established an accepted criteria?

Whether changing a classic taper results in an improved rod is, I think, a strictly personal opinion of the maker or user, but exactly how much does it take to "change, or improve it"? How many new and improved tapers are really out there? Or, are we busy reinventing the wheel?

I think a program written to sort tapers by station measurements would go a long way to answering that. Ascending or descending, line them up in a list and take a look at the differences.  Opinions?  (Wayne Kifer)

I just wonder how you'd prioritize the stations for sorting.  David Ray sent his taper library to the list in a spreadsheet, so the sorting isn't that difficult, just the deciding which should be the first one sorted.  (Neil Savage)

I must missed that post. I'll have to look for it in the archives. Any idea when that was posted? What month, etc? Depending on the spreadsheet, if it's read only, or can be added to it could be sorted by any number of keys. I'll have to dust off my Excel, if that's the format, but it might be interesting to play with.  (Wayne Kifer)

You can easily export the entire RodDNA taper library by saving a copy of it to your hard drive then opening the .RDM file (which is really just an XML file) in Excel.  (Chris Carlin)

Here is a link to a excel file I just created that is sorted by the taper values that I derived from the released version of the RodDNA models/tapers file.  Note that it is sorted by all the taper values  concatenated as one string vs. sorting each value from station 0 to station individually.  It is still interesting.

You can also compare taper values of selected models in RodDNA.  (Larry Tusoni)

Improving a taper sort of says there's something about the taper that you don't like or you feel could be improved and then the taper would be just right. For example Garrisons rods are a little weak in the butt so a mod to strengthen the butt would be an improvement, at least to so people.

You mentioned the Payne 98 as a rod you really like, well if you look at the stress curve you will see it is not very smooth, maybe some would like to smooth it out in the hopes of getting a better power transfer through the rod. Just because they are classic tapers does not insure that they can't be improved.  (Bob Norwood)

Improved? In the eye of the holder - maybe,  I had cast an original and several other's rodmakers Payne 98's. I like the medium/fast action but it felt more like a 4/5 in my hands. So I used the Payne 98 stress curve and came up with a lighter version taking into account the addition of a second ferrule converting it into a three piece. Lately I'm gravitating toward medium action and so that is what I stove for, a rod that with the additional weight and modifications in the dimensions was a tad slower while loading with just a foot of line and 9' leader, yet it retained the power to easily cast 45 feet, with the flex stopping just before the grip. Would I say improved, for me it's a delightful small stream rod that fits in my suitcase. I gave up years ago trying to recreate classics. As a hand planer working with five inch settings everything that was done by a taper beveller can not be duplicate.  The best I  can do however is come up with something I enjoy by modifying a classic, but it's not a Payne 98!  (Tim Pembroke)

I am hoping to copy the taper of a rod which has been impregnated with bakelite.  Taking into account that the impregnation process has probably stiffened  up the rod blank.  Should my blank be beefed up a bit to allow for the difference in resistance.  I think it should but by how much?  (Gary Nicholson)

Interesting you should ask.  I was reviewing the archives just this morning and the answer to your question was dependent on whom you asked.  The range was from no change to 10%.  But what is 10%.  Someone’s GUESS as to how much the action changed.  The general consensus was that SOME stiffening occurred but no one offered any concrete test data.  I saw one comment on a test done by hanging a weight on a tip section before and after impregnation and the tip deflected MORE after impregnation.  I don’t know whether that tip was fully cured before the test.  The other consensus was that impregnation makes a rod real “noodly” until cured.  (Al Baldauski)

I don't know all I can say is the ones I have tried have been stiffer I would say. But I really think they don't deflect any quicker. But that means the line rating could go up a size. The 10% could be about right.  (Gary Nicholson)

I found an article at the Forest Products Laboratory web site that generally discussed impregnation and some of the materials used.  It seems that some materials will actually reduce the stiffness.  (Al Baldauski)