Has anyone seen Scimitar's downloadable video for static test guide placement using their "Sine Wave" method? It was rather interesting to see the blank being flexed back and forth creating a Sine Wave type pattern against a lit background and where the two arcs continually crossed each other while being flexed was THEE spot for a permanent guide location. The other guides are now moved up and down the blank to remove flat spots in the line both above and below THEE spot. Has anyone followed this method as part of their guide placement ritual? Thanks.

Tim Collins

TIM ,check your mail. John

This is what was known as the "nodal" point in older versions. But it doesn't make as much sense as you might think. The original idea was that you didn't want the blank flexing back and forth after the cast without a guide exactly on that spot. The thought was that this would keep those oscillations from robbing you of distance.

Now take any graphite rod you've got there and go cast it. Watch what it does after the cast. Does it waver back and forth for several seconds? Does it move and continue to "bounce" as it did in the "sine wave" placement test? Of course not. It bounces one time and then comes to rest.

There are a lot of ways to adequately place guides on a rod blank. I have no doubt you can do it with the method you mention. But failing to locate a guide on the nodal point does not mean you have the wrong or inaccurate placement.

Check the online library here for another take on static guide placement.

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Tim,
I am familiar with this scheme for guide placement but I do not buy the logic that I have seen to justify or explain it. The reasons that I don't buy it can get a little complicated and would take quite a bit of space here, but basically there will be no node unless the rod vibrates at a frequency that is twice it's resonant frequency or multiple of that which never happens when a rod is in actual use. The node that you see in the center of the rod when you vibrate it is because you are exciting it, or putting energy in, at twice, or higher, of the rods natural frequency or resonant frequency. Plus as each guide, or any other weight, is added the resonant frequency will drop and naturally the multiples of the resonant frequency will also drop and the location of the node will change or move. If you want to discuss this further send me an e-mail.

Yes, as soon as you the add the guides, the nodal point changes!

It's one of those things that sounds good in advertising but when put to actual use on the water, doesn't really hold water. Pun intended.

You guys check me if I am wrong on this, but with a flyrod, isn't one of the major goals to dampen the oscillations that make the nodal point visible in the first place?
We have had 10 page discussions over on the www.sexyloops.com board on how controlled drift coupled with a crisp stop and a relaxed grip form a much tighter "V" shaped loop as opposed to the lazy "U" shaped loop thrown by most of us. The reason really good casters get that tight V or wedged shaped shaped loop is because the drift helps dampen the rod which equals less oscillations to throw distance robbing waves in the line.
I would think that shaking a rod back and forth to find the nodal point is a bit of a waste of time because the shaking back and forth is what you want to eliminate in the first place. The whole point of using high modulus material is that when the rod unloads, there are less oscillations thus recovery time is much quicker.


Andy Dear
Lamar Reel Seats

Andy,
There is a difference between the resonant frequency and damping rate. The resonant frequency is the natural frequency at which the rod will oscillate or vibrate when excited. When you see someone shake a rod and a node forms somewhere in the middle of the rod it is because they are shaking it at a rate higher than it's resoanant frequency and as long as they shake it, or put energy in, it will continue to vibrate.
On the other hand the damping rate is the length of time it takes the rod to quit oscillating after it has been excited and the excitation is removed.
You are correct that, all other things being equal, a rod made from a high modulus material will have both a higher tip velocity (unloads faster) and will also damp out oscillations at a higher rate.

OK, ok .... Time to "fess up". That's really my clip excised for comment (which I see I am getting - lol ). Going through some of the comments from above. The "nodal cross over point" did not change after the guides were put on (I just re-ran the test with the guides on). And I flipped the rod back and forth at different speeds - trying to defeat the resonant frequency - no change - although it's probable that I was inducing a harmonic / sub-harmonic of the original sine wave that is generated which would have replicated the original cross-over. I understand resonant theory - used it for many years in electronics (from cutting antennas to analyzing signals). Exciting the rod to find the cross-over will not make one iota of difference in the performance of the blank nor change a person's casting style ( I will go find those 10 pages though because I can use lots of help with casting). What does happen ('cause I just tried this too) is that different blanks (different IM ratings) will "cross over" closer to the tip the higher the IM rating is -- I think that's kinda predictable as the blank's major flex is nearer the tip top than a fiberglas(s) rod. Is doing the 'sine wave' thing worth doing -- I think the jury is out - which is why I put that little cliip out there hoping it would find it's way back to some discussion boards. It could well be unnecessary. What it does NOT / NOT do is replace a static test or a 'backyard flip o' the wrist". What I think it does is provide a starting point for a static test - again I could be wrong ( I've been proven wrong many, many times - and hopefully learned each time). The second reason that the clip is "out there" is that it is the first time that I have ever seen the effect captured on video and since it's on digital media it can be slowed down to very slow - frame by frame speed without blur.

Ken,
If you lock down the butt of the rod, deflect the tip and release it you will see that there is no node as the rod oscillates. The rod is oscillating at it's resonant frequency or natural frequency. If you then take the rod in your hand and shake it so that there is a null close to the center of the rod, depending upon the rods action, it will be oscillating at the second harmonic of the resonant frequency. There is a null and also two points of higher deflection or a standing wave in the rod because you have put energy into the rod at higher than it's resonant frequency. If you shake it faster you can sometimes, with some rods, force it to oscillate at the third or higher harmonic. But you have induced these higher harmonics by putting energy into the rod at higher than the resonant frequency.

When you add weight, guides or whatever, you lower the resonant frequency of the rod/blank. The more weight that is added the more the resonant frequency will be lowered. When the resonant frequency is lowered naturally the harmonics are also lower. You did not see the null point move when you added weight because you put energy in at a slightly lower frequency than previously. If you could control frequency that you put energy into the rod, the frequency that you shook it, the null point would move. You add weight, the resonant frequency lowers, the null point has to move.

I do not think that any of this proves anything about guide placement because the rod in actual use will never be oscillating at anything other than it's resonant frequency or lower. I can not think of any actual use of a rod, other than a fly rod, where it would be oscillating at anything other than it's resonant frequency or lower, usually much lower.

The only reason I said "other than a fly rod" is because some fly casters try to induce a second harmonic when they cast to get higher tip velocity so that they can cast farther.

I knew that this discussion was going to get out of hand.

There's nothing wrong with using the "nodal" point to aid in guide placement. But previous claims over the years have tended to suggest that having a guide at that exact location will somehow contribute to longer casts and quicker damping. It won't. (I'm not suggesting that Ken has made such claims - I have not seen the Scimitar video.)

We know how to determine the first guide behind the tip. We know how to position the butt guide. If a builder would like to use the "nodal" point as a basis for locating a 3rd guide, and then work on static placement from there, that's fine. It's just another method for helping some builders out with this facet of the craft. I think there's better ways to set guides up, but see nothing wrong with using this method if it helps. You just don't want people getting the wrong idea about any supposed benefits having a guide located at that exact point offers.

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Em -
I surrender! You're right there is no way to ensure that the rod is moving at exactly the same speed minus some constant electro-mechanical device. At the resonant frequency, half the resonant frequency, double the frequency or second harmonics of each. I still would like to do some "measure of worth". First because this is supposed to be fun and second because there is enough bogus information out there already without me (or anyone else) introducing another red herring. And I (again) admit it -- in the clip it just looks cool.

So where is this video?

Emory,
You said " I do not think that any of this proves anything about guide placement because the rod in actual use will never be oscillating at anything other than it's resonant frequency or lower"


@#$%& bells.....for once you and I actually agree on something.


Andy Dear

Andy,
Maybe we should think about it some more and one of us change our minds. It just will not do that we agree.

Folks -

The video clip Tim referred to can be found at:

[www.scimitarvideo.com].

Cheers,

Mike