[dictionary.cambridge.org]

LOL

I’m sure many of you have tried the old hummmmm test as a subjective sensitivity test. It been around for a very long time. It takes two people to perform. One holds the blank/rod and is the vibration sensor the other is the vibration generator. Basically the blank/rod tip is placed against the throat of generator at the V of the neck, who then hummmmmmmms. The sensor then determines how well these vibrations can be felt. Try it, every blank/rod I’ve tried will transmit these hum vibrations quite well. Does this mean that almost all blanks/rod are sufficiently sensitive? It seems, that some are trying to find a method for quantifying this type of sensitivity test. I’m sure there is a controlled way to do it, which will yield reproducible and objective numbers. Good luck with your endeavors and let us know how it goes.
Norm

Michael, as to whether I believe TNF is an indicator of sensitivity, I am still trying to wrap my head around it.

If I have this right, you're measuring the osculations of the blank. The higher the number, the more times an osculation occurs over a defined time period. Since it is well accepted, and I have come to totally agree, that stiffness to weight ratio is the determining factor for rod sensitivity, then TNF is basically a measure of stiffness to weight ratio? If I have it right, then I believe TNF is proportional to sensitivity. If I don't have it right, then I am still lost. lol

As far as ERN is concerned. I honestly doubt I will ever become comfortable with it. It's not linear. The jump between neighboring ERN's could be 30 grams, while the jump between another pair of neighboring ERN's could be 50 grams. There is no, this many grams equals one ERN. At least not that I can see. And the latter has been something that has been brought up in past threads where the usefulness of ERN numbers has been discussed. It just makes no sense to me that a number related to weight, isn't expressed in a value of weight.

I've been looking more at the numbers Norman posted, comparing them and trying to see if I can identify a relationship between IP, AA, and TNF. There appears to be within each blank family, but the difference between the 2 families are quite different. At least to my reasoning

Looking at the numbers, I looked for 2 blanks from each manufacturer that had close to the same difference in power. I chose the NFC SJ 703, and the SJ 732. The 2 blanks have a 79 gram difference in power. From Point Blank I chose the 691 MLXF, and the 701 MLF. They have a 87 gram difference in power. The AA's are basically reversed when comparing the combination of IP and AA for the blanks from each manufacturer. It appears as if action plays a larger part in the TNF numbers from the Point Blanks, than it does with NFC. The difference in cpm for the 2 NFC blanks is only 12 cpm. The difference for the 2 Point Blank blanks, is 82 cpm.

If you average the IPs for the blanks from each family. there is a 3% difference in cpm for the NFC blanks. And a 14% difference in cpm for the Point Blank blanks. Not an apples to apples comparison as the lower powered NFC blank has the lower AA, while the higher powered blank from Point Blank has the lower AA. I just thought that the difference was pretty significant.

I know one thing .... I am REALLY going to have to build on a Point Blank blank, just to see what all the hub bub is all about.

David, you are interpreting TNF correctly The data are presented in cycles per minute. Note that the higher the TNF the faster the blank/rod recovers from being deflected. It cannot be any other way.

Yes, TNF is basically a measure of stiffnes to weight ratio. But not necessarily exactly since geometry (length, diameter, taper, wall thickness, etc) is probably involved. Keep in mind that neither I nor anyone else knows everything about it yet. But it looks good so far. But there is more to learn.

I agree that ERN has some problems. This might get us both in trouble, but ERN is , in my opinion, somewhat an arbitrary number to, I believe, make it fit the old fly line weight designations with parallel numbers. So that what we called an ERN 6 fly rod would cast well a 6 weight fly line at some ideal distance. If we want to have a more reliable measure of stiffness then we should be using the CCS grams to deflect to 1/3 the length of the blank/rod and not ERN. . It is easier to relate to ERN than to grams. Who can have a gut feel for 400 grams? But it's easier to think of a rod with an ERN of 20 as being about twice as powerful as a 10 weight fly rod. (I haven't looked at the chart so don't know if ERN 20 = 400 grams) OK, CCS purists, climb all over me. (I believe that CCS is one of the most powerful developments ever in fishing rod knowledge. But for this particular application, it just might be better to use grams instead of ERN) . I have not yet done it, but since the TNF is sort of a measure of stiffness to weight ratio, could it be that all we have to do is divide the CCS power grams by the weight in ounces and have an emulator of TNF?

The important thing in discussing TNF, ERN, and AA is that they are totally independent of each other. One has no relationship to the other. It's possible to get just about any reasonable ERN or AA on any blank/rod material. HOWEVER, it is likely that one cannot get the higher TNF's with glass. Because glass probably, at almost any geometry, cannot have the stiffness to weight ratio that will yield a really high TNF. Its modulus is lower than most if not all graphites.

Action does play a role in TNF if some of my initial tests hold up with more data. It appears to be easier to get a high TNF with XF actions than with moderate actions. I think it is because their tips are lighter. But I don't know everything yet. I have one RX6 blank that is an XF action, about 82 AA, and its TNF is surprisingly high, even as a finished rod. It also appears to be easier to get a higher TNF with higher power blanks. This may or may not be true, but if true it probably relates to the geometry.

Length plays a role, here , too. If you look at the cantelever beam formula for natural frequency, Length is in the denominator, which means as length goes up natural frequency goes down. It's easier to get a high TNF with a shorter rod than with a longer rod. Recent measurements by another builder varied the butt anchor points, essentially changing the length of the blank and the natural frequency increased as the blank go shorter. HOWEVER, there is an argument that longer rods are more sensitive than shorter rods due to the longer lever arm the rod essentially makes when held in the hand. How these arguments trade off I don't have a clue.

Generally I've found the higher the modulus, the higher the TNF, which is good to know. It indicates that we are usually getting something for our high bucks we pay for premium blanks. Is it worth it? It's up to everyone to come to his own conclusion, but it's comforting to know that generally the higher the price/modulus the more likely one is to get higher sensitivity.

For the naysayers, let me repeat. I don't know everything about this process yet. I think what I said above is true, but I am not perfect. Ask my wife.

Your desire to build on a Point Blank is well founded. They build into very fine rods.

A sensitivity test that is measurable, and accurate. I don't have the required equipment, but do have a bachelor of science in electrical engineering tech. Here's how it could be done. You will need a dual trace, O-scope with memory to capture and hold traces over a period of time, a transducer that will turn vibrations into DC voltage (accelerometer), a light weight to simulate a fish nibble.

Attach the transducer to the rod blanks you wish to test, at the handle where you hold the rod. Attach the O-scope probes to the transducer. attach the reel, and then thread the line through the rod guides and tip top. Attach the light weight to the end of the tippet. lift the weight a measured amount, like maybe a quarter inch, and drop it straight down. Record the voltage amplitude shown on the o-scope when the weight was dropped. The greater the amplitude, the better the blank is at transmitting vibrations to the hand, i.e. the more sensitive the rod is.

Next, tap the rod tip with something hard, and measure the frequencies between the better, and less sensitive rods, and see if there is a a marked difference thatis consistant for multiple blanks. These tests will allow you to determine sensitivity by comparing different tapers, materials, actions, modulus, which tipes of line/leader/tippet give the best feedback, etc. With all of the knowledge you obtain, publish a book on it and make some cash to pay for your exhaustive tests, and time.

Tight Lies and frisky fish

RJF

David, you write: " It just makes no sense to me that a number related to weight, isn't expressed in a value of weight."

It is a number that is intended to describe the power of the rod relative to other rods. It is a "manufactured" number as I tried to describe earlier. So you can know that a 10 is slightly more powerful than a 9, much more powerful than a 6. And if it's a fly rod it will cast a properly made 10 weight line well. Yes, the true indicator of the power of the blank/rod is the number of grams (or any other unit of weight) that it takes to bend the rod tip to 1/3 its length when properly held. ( Using the CCS system. There could be other systems to describe power.But CCS is one that many of us understand and use, so it has more value than some other system that none of us know about).

How much influence does the natural frequency have upon the performance of a finished rod? Has anyone measured and recorded an increase (or decrease) in distance or accuracy due to a higher (or lower) TNF, or must we rely upon speculation and predictions? I am hesitant to accept a fisherman's undocumented account of the length of a fish he caught or the performance of the rod he built!

Run the process, come to your own conclusions.

It would seem practical anglers would be interested in the resonant frequency when a rod with a rod, reel, guides, tip-top and line is being cast, and not as interested when there is no reel, guides, or line - just a bare blank. Is there any way of determining the resonant frequency of a rod while it is actually functioning - casting - and if so what is the best rod frequency for long, accurate casts?

Norman Miller Wrote:
-------------------------------------------------------
> I’m sure many of you have tried the old hummmmm
> test as a subjective sensitivity test. It been
> around for a very long time. It takes two people
> to perform. One holds the blank/rod and is the
> vibration sensor the other is the vibration
> generator. Basically the blank/rod tip is placed
> against the throat of generator at the V of the
> neck, who then hummmmmmmms. The sensor then
> determines how well these vibrations can be felt.
> Try it, every blank/rod I’ve tried will transmit
> these hum vibrations quite well. Does this mean
> that almost all blanks/rod are sufficiently
> sensitive? It seems, that some are trying to find
> a method for quantifying this type of sensitivity
> test. I’m sure there is a controlled way to do
> it, which will yield reproducible and objective
> numbers. Good luck with your endeavors and let us
> know how it goes.
> Norm


Norman - try this same test with a wooden broom handle. It does quite well, better than many carbon rod blanks in fact.

................

Tom Kirkman Wrote:
-------------------------------------------------------
> try this same test with a wooden broom
> handle. It does quite well, better than many
> carbon rod blanks in fact.
>

I bet it scores a higher than 11Hz TNF as well! Might even break 11.00000000000001Hz!


Chris Catignani Wrote:
-------------------------------------------------------
> Tom Kirkman Wrote:
> --------------------------------------------------
> -----
> > The point is that the old tackle shop salesman
> > "Adam's Apple" test for sensitivity wasn't a
> good
> > test after all. I'll save the story for an
> issue
> > of RodMaker. I still laugh about it whenever
> this
> > comes up.
> >
> > ..............
> Awesome...I have a similar story (actually from
> the same era) about being able to feel a crack in
> the floor...


And I'd bet that one had TNF of 617cpm or 10.2833333333333333333333333333333333333333333333333333333333333333Hz and it sure beats a rod with 10.266666667Hz TNF! Time to change reference so it looks better and sounds better and more relevant spread out. 617cpm. All fixed.



Edited 4 time(s). Last edit at 04/05/2022 07:44AM by Kent Griffith.

Phil, run the process, come to your own conclusions. You always expect someone else to answer your questions. Do the work. Answer them yourself.

Kent Griffith Wrote:
-------------------------------------------------------
> Tom Kirkman Wrote:
> --------------------------------------------------
> -----
> > try this same test with a wooden broom
> > handle. It does quite well, better than many
> > carbon rod blanks in fact.
> >
>
> I bet it scores a higher than 11Hz TNF as well!
> Might even break 11.00000000000001Hz!


I have an interesting story regarding this but won't go into for now. It was, for a time, how tackle shop owners in the 70's and 80's attempted to show fishermen how sensitive the new graphite rods were... You'd be surprised how many "dead" materials will actually do better than carbon rods in this particular capacity.

..............

"Norman - try this same test with a wooden broom handle. It does quite well, better than many carbon rod blanks in fact." And the point is? That the test may not be the best test for sensitivity? You might be right, but it's interesting to oonsider. If there
is more meaning in your comment, please clarify.

I bet it scores a higher than 11Hz TNF as well! Might even break 11.00000000000001Hz! And the point is? ????

"Norman - try this same test with a wooden broom handle. It does quite well, better than many carbon rod blanks in fact." And the point is? That the test may not be the best test for sensitivity? You might be right, but it's interesting to oonsider. If there
is more meaning in your comment, please clarify.

I bet it scores a higher than 11Hz TNF as well! Might even break 11.00000000000001Hz! And the point is? ????

The point is that the old tackle shop salesman "Adam's Apple" test for sensitivity wasn't a good test after all. I'll save the story for an issue of RodMaker. I still laugh about it whenever this comes up.

..............

Michael, I get that CCS measurements are used to compare one blank or rod to another. ERN is the term CCS uses for the power of a rod. The power of the rod is determined by using weight to deflect the blank, so ERN is weight based. The higher the ERN number. the more powerful the rod.

It would be no different if grams were used. A rod with an IP of 500 grams is less powerful than a rod with an IP of 800 grams. The same usefulness comparatively, except I know how many grams are in an ounce, I know how many ounces are in a pound. Let's say a rod has an ERN of 20 and I want to know how much weight it took to deflect the blank 1/3 of its' total length. How do I find that out? ERN 20 ..... couldn't tell you. IP of 800 grams I can tell you how many ounces, how many pounds, it took to deflect that blank the required amount.

I can look at the deflection profile of the blank under that load. If want to look at the deflection profile of the blank at half that load I cut the weight in half. You can't do that with an ERN number.

And you're right showing the concern you did with saying something in CCS terminology may be problematic. It is normally not very well received. But saying ERN isn't easily related to is not saying the whole system is flawed. It's not even saying ERN is flawed. It is a number used to compare one blank to another. Period, end of sentence. It is what CCS was designed for. I get that. But .....

What if AA wasn't expressed as an angle? What if it was expressed with a number that nobody knew what it was?



Edited 1 time(s). Last edit at 04/04/2022 07:56PM by David Baylor.

Mick - After reading that vibration transmission is the measurement that really counts for determining sensitivity I brought up the hummmm test or Adam’s apple test (as Tom calls it). This test clearly illustrate that almost any blank/rod, including broomsticks and PVC pipe, will transmit these hum vibrations extremely well. Many rods were sold using this subjective sensitivity test. So, if vibration transmission is best way to measure sensitivity, then the question becomes: Are all rods sufficiently sensitive? Based on this, I would have to say yes. Maybe it’s not sensitivity that we are trying to quantify, but rather ‘feel’. In Dr Hanneman’s article on CCF, he never mentions sensitivity, but talks a lot about ‘feel’. I’m sure sensitivity is involved in ‘feel’ but it’s not the only thing. He believed that the natural frequency at which a blank/rod vibrates plays an important role in feel. He stated that most fishing rods had a natural frequency between 100 - 600 cpm, to fast for the human eye to count and thus require expensive equipment to measure. His simple and inexpensive method for measuring frequency was to add weight and slow down the frequency so it could be counted. He used this method to quantify frequency on a relative scale. Micheal’s method using the frequency counter app quantifies frequency on an absolute scale. We have been very consistent in saying that frequency measurements are not measurements of sensitivity, but rather just frequency, nothing more nothing less. So I hope my reasoning is clear.
Norm

David - I agree with you about ERN, and raised the same concerns in a number of previous posts. In all fairness, I think Dr Hanneman was concerned that if power was defined by IP some people might think it was the maximum weight the rod could cast. Not a good thing.
Norm