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Rule

I have a question for the folks using RodDNA.  I believe someone mentioned to me that ROD DNA takes into account the difference in stresses when using NS ferrules to join the rod sections.  This has prompted me to do some testing.  As if for example:

I generate a new rod by changing the number of pieces of the Garrison 212E from 2 piece to a 1 piece rod, then when I highlight both rods and look at the charts, both stress curves apprear to be virtually identical.  I was anticipating that if the stress curve generated by ROD DNA took into account the different stresses of the metal ferrules that there would be a distinct difference in the stress curves at the ferrule location between the one piece rod and the two piece rod.

Can someone explain what I'm missing?  (Wayne Daley)

    I also checked the station dimensions at the 45 and 50 inch stations, either side of the ferrule and they are also almost identical.  (Wayne Daley)

      You have asked a good question. I don't use RodDNA but do have my own program for rod design and analysis and what you should see in the DNA data, is a decrease in the one piece taper starting at the 50" point and decreasing more as you go toward the butt. This should be the bamboo that was necessary for offsetting the ferrule weight on the two piece rod. Since the decrease at the 50" point is less than one thousandth of an inch maybe DNA is not set to calculate this small a value, but you should see it as you go down toward the butt. In fact it gets to be 7.79 thousands at the 80" point.

      I have attached a print out of one of my pages which opens with Adobe reader, showing the values which should be corrected for when removing the ferrule of 13/64 to make it a one piece rod. The values are in the second column from the right.  (Bob Norwood)

        Thanks for taking the time to answer.  The ROD DNA program does change the station dimensions below the 50" station, pretty much as you describe below.  I guess I was just expecting a difference to be evident in the area between 45 and 50 inch stations where the ferrule would be located.

        Here are the numbers I get using ROD DNA first set are a 2 piece rod with a ferrule, second set is a 1 piece rod.

        Station

        2 piece

        1 piece

        0

        0.071

        0.071

        5

        0.085

        0.0851

        10

        0.106

        0.1061

        15

        0.124

        0.1241

        20

        0.138

        0.1381

        25

        0.152

        0.1521

        30

        0.165

        0.1652

        35

        0.177

        0.1772

        40

        0.189

        0.1892

        45

        0.202

        0.2022

        Ferrule at 48"

        50

        0.214

        0.213

        55

        0.228

        0.2246

        60

        0.241

        0.2357

        65

        0.254

        0.2472

        70

        0.267

        0.2589

        75

        0.281

        0.2718

        80

        0.296

        0.2858

        85

        0.330

        0.3182

        90

        0.340

        0.3276

        95

        0.340

        0.3275

         

         

         

         

         

         

         

         

         

         

         

         

         

         

        (Wayne Daley)

    Graph the actual numbers of the two rods, you will most likely find that the difference is in the diameter of the rod, not in the stresses. The diameters will change to account for the difference in the ferrules.  (John Channer)

      I did also look at the diameter chart and there was some difference but it was only in the butt below where the ferrule would have been located. Between station 45 and 50, where the ferrule would be there was no difference in the 45" station and the 50" station was only different by .001", yet the stresses showed as the same for both the 2 piece rod with a ferrule and a 1 piece rod without a ferrule at both the 45 and 50 inch stations.  I guess I would have expected either a greater difference in the dimension of the bamboo at the 45 and 50 inch stations, if the stress were held constant by RodDNA, which I believe they are when converting a rod from a 2 piece to a 1 piece.   I'm having a little trouble why the stresses, at this location 45 -50 inch station, are the same without a ferrule as they are with a ferrule when the rod dimension  is virtually the same at the 45 - 50 inch stations.  (Wayne Daley)

        I don't have RodDNA or know how to use it, but with Hexrod, I would expect the diameters to change more as you get further towards the end of the rod, right at the ferrule station I would expect the least amount of change. Does DNA show more of a change further away from the ferrule?  (John Channer)

Rule

Many thanks for the work Larry Tusoni has done and especially for creating software that any rod maker with a computer can use. Most of my original tapers are the result of screwing up the forms, or miscalculating with the indicator. Some have been fortuitous successes, but one sits in the corner to remind me that some rods just feel like garbage.

I do quite a bit of taper modification to keep rods constructed with differing components felling the same. I miss a more robust way of handling multiple joining techniques. I currently make metal ferrules from two different materials, in 3 different form factors, as well as light weight bamboo ones. Without the ability to expand the ferrule options, I end up doing at least some design work with other programs, then moving the results to RodDNA. A taper made with a light weight bamboo ferrule does not flex the same as one with a NS standard one.

I am interested in looking at step-down ferrules more. Like Bob, I like the way they look. Having an easier way to enter and manipulate tapers at the one inch level would make modeling stepdowns much easier. Modeling the swell for thin wall bamboo ferrules would also be easier with finer granulation.

I doubt that I'd make a good beta tester. I've forgotten more engineering than I remember, and math beyond simple trig makes my brain hurt.. I'd just like to remind you that some of us are more into advancing the craft than carving out clones of some dead dude's life work. Anything you can do to reduce the amount of guessing is greatly appreciated. I suppose modeling hollow building is way beyond reason?  (Larry Lohkamp)

Rule

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