I have been curious as to the efficiency of foam cores to transmit the vibrations (feel) from the blank to the outer skin and ultimately the hand or fingers, be it a CF skinned grip or reel seat insert. If feeling the vibrations of the blank is paramount, then direct contact with the blank itself would produce the ultimate sensation of such. Foam, by nature, possesses an insulating property, both thermally and vibrations. This is accomplished through the random cells of dead-air space and being random disrupts a straight-line path for the vibrations to travel uninterrupted, redirecting the pulses in infinite directions and absorbing the initial magnitude. Obviously, the stiffer the foam the better it will transmit vibrations but, none the less, it is still foam. For the ultimate transmission of vibrations, thin CF washers bonded between the blank and ID of the outer skin or insert might produce the best results, possibly amplify the vibrations. Clearly, such would more difficult to accomplish than simply shaping a foam tube and skinning it with CF sleeving.
Many of you build foam core grips, use reel seat inserts and attest to the additional feel provided. I am certainly not here to say you are wrong. But does it provide the ultimate in sensitivity? Does a foam grip transmit enough vibrations to the palm of one’s hand to offset direct contact of the blank with a thumb or finger? Is it that people simply go gaga for CF these days?

Mark Talmo
FISHING IS NOT AN ESCAPE FROM LIFE BUT RATHER A DEEPER IMMERSION INTO IT!!! BUILDING YOUR OWN SIMPLY ENHANCES THE EXPERIENCE.

Rigid polyurethane foam reel seat shims are so rigid they are brittle. And very light. So I think they are very capable of transmitting feel as well as just about anything. Nope, no data. But neither does anyone else have data on sensitivity.

On spin, if you want to get what I think is the most sensitive (practical) setup, use foam shims for the seat, mount your reel seat up-locking, and do a short ramp of reel seat shim off the front, embedding it in epoxy (wrap epoxy). Your fingers off the front will then be in almost direct contact with the blank. Move them up a bit and they are on the blank. Use size 17 seat like the Fuji DPS and you've got a very comfortable, light, sensitive, set up.

You can turn the ramps by taking a seat shim of the length you want, twist a drill just larger than 1/4 into it, chuck it on your drill press, and sand it to shape. Be careful, they sand down very rapidly. Then be very careful in handling it until you get it reamed, mounted, and coated. After that, very durable. although I don't think it wise to do this for a rod intended for a holder. But for a holder sensitivity isn't needed.

Not all foam is the same. Rigid Urethane Foam is the recommended core material for carbon skinned grips. It's rigidity (stiffness) to weight ratio is extremely high. Many confuse it with foam such as EVA or Hypalon. Very, very different. It's only foam while it is in the curing process. Afterwards it is a lightweight, rigid (hard) bushing.

In short, the rigid foam does not increase sensitivity - but it degrades sensitivity less than say, cork, EVA foam, wood, etc.


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

Mark,

As mentioned the urethane foam is a different animal. If there is space to be filled, it is a great material of choice due to its low mass and rigidity. As Tom says.

With that said, it wasn't uncommon for guys to place plastic poker chips under each side of the reel foot on cork TN handle rods in the manner that you are talking about. A google search or a search on here of all dates should turn up a few threads worth reading. You are certainly barking up a good tree here. However, I think the rigidity of the chips helped prolong the life of the grip and was responsible for any enhanced feel. A sleeved grip is not going to leave you wanting for much more.

Also for some interesting reading material that you will really enjoy, read up about Steve Gardner's Hot Handle. What it amounts to in summary from what I remember is sleeving up a core with an offset bore so the the blank ran along the core with carbon fiber underneath. He would then come back with a sleeve around the whole OD. Finally he would use a solvent to dissolve the foam core leaving a hollow handle with the blank running along your palm. The hot part was that you could toss in a hand warmer to keep you hand warm in the colder months. Steve has done some amazing stuff with rods, well beyond my capabilities for sure.

Inspired by Steve's work, I started building. My first builds use Batson woven graphite fore grips as split grips on casting rods, and straight carbon fiber tube for split TN handles with the reels wrapped on with thread (again inspired by Steve's work, and by far the best way to go if you ask me). Since then the sleeving technique took off and I started to sleeve my own grips as needed, but I like EVA and burl cork grips as well. I've been known to give my rods the old carpet test brushing the tip across various surfaces to feel how things change with a build. What I can say subjectively is that at the end of the day, the total inertia of the build is more important than any individual component in maintaining as much of the feel of the raw blank as possible. Anything you do in the handle area to maintain that feel can be wrecked quickly with a heavy guide train, weight added to the butt (although something can be said about the benefits of a balanced rod in some specialized applications), and or copious amounts of epoxy either adhesive or finish.

Keep the glue lines thin, the guide train light, meet your ergonomic needs, and ask yourself two questions: 1. Is everything I need on the rod there? 2. Is everything on the rod needed? If you answer your questions honestly, you'll know that it doesn't mean to make grips that are so small they are uncomfortable to hold, nor does it mean that you can't add decorative flair to a rod. All it means is that you are meeting the needs of your fishing tool and you understand any tradeoffs you make when adding a bit of flair to the build.

Michael, Tom and Joe,
Thank you for your comments; they are understood and well received. I apologize for any confusion but, as the title of the topic suggests, I was hoping to learn if a foam core transmitted vibrations (feel) as well as direct contact with the blank.
I am quite well versed in foam core technology through my structural composite sandwich knowledge and am certainly not confusing rigid core material with soft foams such as EVA. The original core materials were aluminum honeycomb followed by Nomex honeycomb with rigid PVC and urethane foams developed shortly thereafter to facilitate ease of manufacture and cost of sandwich construction. While PVC/IPN such as Divinycell probably remains the foam of choice for structural applications, urethane foams are suitable as well for rod building. Actually, Nomex honeycomb might be the best core material for rod building but talk about a PITA to orientate the cells radially.
With all due respect, if rigid foam transmits vibrations better than wood then why is wood the material of choice for musical instruments?

Mark Talmo
FISHING IS NOT AN ESCAPE FROM LIFE BUT RATHER A DEEPER IMMERSION INTO IT!!! BUILDING YOUR OWN SIMPLY ENHANCES THE EXPERIENCE.

Wood produces a certain tone that is considered desirable for music.

The mass of the rod and the reel deadens vibrations and fingertips are much more sensitive to vibrations than the palm and lower parts of the fingers which come in contact with the grip. Holding a taut line on the fingertips of your free hand will detect bites better than any changes you can make in the rod.

When it comes to music, it's the air cavity inside the instrument that vibrates and produces the sound. Electric guitars don't sound great without and amplifier. Wood was the best material available when the instruments were developed and cavities shaped and sized accordingly. I'm sure you can engineer an instrument with the material of your choice and with enough work make it sound just as good as a wooden instrument, but you aren't gaining much. With the world famous Stradivarius violin one of the things that make them the best in the world is that the trees they were made from grew during a period cooler than normal climate conditions making the wood a little more dense, which is the opposite of what we strive for in a fishing rod. It's the subtle variations in the reverberation time of the cavity that make each instrument unique. Additionally with a musical instrument, you want those vibrations in the cavity to last longer than you want them to last in a fishing rod. It's about optimizing the reverberation.

When it comes to fishing rods, what you feel is a wave in the sense that it is a disturbance that propagates through a medium, but it's not a vibration in the sense that our hand is a membrane that gets driven by a wave in the way that our ear drum works. What we feel is a torsional wave/signal that tries to rotate the entire length of the rod about its pivot point, i.e. your hand when you are fishing without anchoring the butt of the rod. The signal reaches the rod as a longitudinal wave in the line by means of varying tension in the line. The source of the signal is the impulse or change in momentum of the bait. Every tick you feel is something causing the lure to slow its approach to you, i.e. a pull on the lure. Anything that pushes the lure forward significantly will put slack in the line and your signal disappears. In order to maximize the feel in the rod, the line needs to exit the tip top perpendicular to the rod due to the fact that we handle the rod by the outside of the blank, push/pull or longitudinal waves won't transmit vibration to our hands. So, how do we feel in the rod, well when those changes in tension make their way up the line, there will be changes in the force on the tip of the rod. The force at the tip of the rod applies a torque about the rods axis of rotation, i.e. tries to make the rod rotate along its length in your hand. Each impulse (pull) your lure experiences gets transmitted to the rod.

Now we need to talk a little bit more about wave mechanics. When that impulse enters the rod, it is not a single frequency driven wave. It excites all of the harmonics of the rod to a varying degree producing a complex wave. When an impulse wave travels through a medium, it's wave form will spread and its amplitude will shrink over time. As that impulse hits the ends of the medium it reflects and bounces back and forth in the medium until it decays away. In order to get the best signal from the line to your hand, your rod needs to react quickly to the impulse and then damp the vibration as quickly as possible to limit the amount of interference.

So, what governs how quickly your rod will respond to a signal and damp the residual signal? You can think of it as a stiffness to weight ratio, or you can think about it as the moment of inertia. Everything you do to a rod blank decreases its stiffness to weight ratio and increases its moment of inertia. Since we are talking about a torsional signal that we want to feel, its the moment of inertia that determines how much angular acceleration the rod will experience for a give torque (rotational force). At the end of the day we want to feel the largest acceleration for the smallest input force possible, doing so means keeping the moment of inertia low. We want the residual noise of the signal to dissipate quickly after it passes our hand for the first time. This is accomplished by using a stiff medium with low inertia.

To summarize, the thunk you feel when a fish takes a jig is the initial impulse and the signal that you want. The 'fuzziness' you feel around that thunk that makes it seem less crisp is the transverse waves decaying away in the blank. You'll notice that higher modulus blanks will give a cleaner feeling thunk than lower modulus blanks. It's because those blanks have a higher stiffness to weight ratio, and a lower moment of inertia than a lower modulus blank with the same action and power. Keeping the thunk as clean as possible means keeping the overall moment of inertia of the rod as low as possible.

If you can achieve a lighter grip using thin rigid arbors, you will come out ahead, as that is what is going to impact the inertia of the rod. If you can't, then it'll be a wash at best.



Edited 2 time(s). Last edit at 08/08/2020 09:22AM by Joe Vanfossen.

Thank you to those contributing additional comments.
Joe, I truly appreciate you taking the time to reply with such a knowledgeable, in-depth and understandable explanation. The most important issues you mentioned dealt with moment of inertia and modules of the material; in this case we want the smallest moment of inertia (highest stiffness to weight ratio) and the highest modules (density). While the typical foam core material has a fairly good stiffness to weight ratio, its density is extremely low. Hence my original question if a form core is as good as direct contact with the blank.
By the way, I have heard that some seriously world-class acoustical instruments are being fabricated from CF. That certainly supports your comments and my understanding of moment of inertia and modules.

Mark Talmo
FISHING IS NOT AN ESCAPE FROM LIFE BUT RATHER A DEEPER IMMERSION INTO IT!!! BUILDING YOUR OWN SIMPLY ENHANCES THE EXPERIENCE.

Hence my original question if a form core is as good as direct contact with the blank. I think Tom answered that. I don't see what the relevance of "moment of inertia" is. In my opinion, the rigid poly is as good as it gets. Until you find a zero mass material with infinite modulus of elasticity.

Mark
Tom and Joe are both correct
The expanding urethane foam under carbon skin is definitely better then - cork, EVA foam, wood . but still has a dampening effect on the rod.
For that reason (with the exception of the first couple of core grips built) I've always removed the foam.

Michael
Rigid poly - Is not even close to "as good as it gets". but you will NOT find those materials for sale in the rod building industry
With that being said: those other materials still come in second.

The absolute best scenario for maintaining the blanks sensitivity. is to eliminate the need for arbors altogether , something harder to achieve with bait casters.
but easily done with spinning rods.

If you have not read the article on the Hot Handle in Volume 11 #2 – RodMaker Magazine. You might want to order a copy to see how it can be done.

Phil
While it may be true for some people that their finger tips may be more sensitive then their palms, that is not the case for many people who work with their hands for a living.
Being a plumber to for the past 46 years, I've cut my fingers 100's if not 1000's of times over the years, between that and the calluses. the palms are much more sensitive the fingers
which is the reason developing out of the box ways of maintaining the blanks sensitivity.

every time i see a discussion about sensetivity it,s always looked at as if it were a rod problem never a line problem but i guess that,s because it,s a rod-centric site..lol..the use of braided line has cured all my sensetivity issues even for glass rods...

Sensitive / adjective

1. quick to detect or respond to slight changes, signals, or influences.

Direct contact real seats that are sized to the blank are going to be more sensitive than a seat with a foam core. I believe a baitcaster type rod is going to be more sensitive than a spinning because you are always in direct contact with the reel and the seat at the same time whereas with a spinning set up you are holding the rod and only the foot of the reel. Of course, if there is blank exposer on the seat even with a core material then you have direct contact with the blank (obviously). Spinning real seats like the SK, are uncomfortable to me to fish with, so I usually do a seat that uses an arbor. I think it really comes down to the density of the arbor. An arbor made from the same material as the blank will transmit vibration as well as the blank itself. Then we get to the line, because everything that is coming to the rod comes from it. The stiffer the line (density) with less elasticity, the more it will transmit vibration. If you are using mono it is probably going to be the least sensitive with braid being the most (not sure what braid type is more sensitive) and fluorocarbon being somewhere in between. The line touches the guides and transmit the vibration to the blank. They are very good at it because they are made from metal that is denser than the blank. There is little impedance in the medium for vibration to travel through with more being in the blank itself. The more guides on the blank, the more vibration will be transferred to the blank but also the more weight to the rod. I believe carbon fiber grips with some type of internal baffles to anchor to the blank instead of foam, would be the most sensitive grip and most likely lighter than foam cores.

So, it is a balance of components that make a system that will yield the most sensitive fishing rod.

Antonio Stradivari used unique shape, form and a wood that was treated with borax, fluorides, chromium and iron salts among other things to protect it from woodworms to create the greatest violin ever made. He made about 1,200 during his life.

What is the frequency range and amplitude of the vibration one is expected to encounter?

i think the most important quality of braided line is it,s finer diameter which means less drag or less line belly when moving through the water..it,s in a much more direct contact with the rod..

If you need more sensitivity just use a smaller bobber.

you mean "strike indicator" don,t you Phil..lol.

Thank you for the continuing replies.
Michael, if you take the liberty to say Tom answered my question in his reply then I’ll take the liberty to say his reply supports direct contact with the blank is more sensitive than foam core grips and seat inserts.
I think Steve is on the same page as me by suggesting “… is to eliminate the need for arbors altogether…” However, I think my finger tips are more sensitive than the palms of my hands and I, too, have cut my fingers uncountable times within the 25 years I was in the glass (not FG) industry.
Ben, I agree with all you said. However, one needs to hold the rod hence my questioning which method will transmit the most feel.
Lance’s first sentence seems to parallel my thinking but the third sentence seems to be contradictory unless he is referring to removing that portion of the core to match the cutout(s) in the seat to expose the blank itself.
John, I haven’t a clue except “fish frequency”.
This has been an informative discussion for me and hopefully others as well. I cannot really say I disagree with any of the responses offered in the gracious replies. I certainly agree that a proper foam core may degrade sensitivity less than conventional materials, with EVA probably the worst, but believe DIRECT contact with the actual blank itself may produce the best detection of what is happening at the terminal end of the line. My hands and fingers are admittedly a bit numb from years of abuse so I’ll continue using cork grips with split seats or mill blank-exposure slots in conventional seats for freshwater applications.

Mark Talmo
FISHING IS NOT AN ESCAPE FROM LIFE BUT RATHER A DEEPER IMMERSION INTO IT!!! BUILDING YOUR OWN SIMPLY ENHANCES THE EXPERIENCE.

Steve Gardner Wrote:
-------------------------------------------------------
> Phil
> While it may be true for some people that their
> finger tips may be more sensitive then their
> palms, that is not the case for many people who
> work with their hands for a living.
> Being a plumber to for the past 46 years, I've cut
> my fingers 100's if not 1000's of times over the
> years, between that and the calluses. the palms
> are much more sensitive the fingers
> which is the reason developing out of the box ways
> of maintaining the blanks sensitivity.

Yeah, I can claim the same malady from handwork jobs and hobbies, but even if not the situation is the same from most anyone once those fingers get cold from fishing in chilly weather. Wouldn't surprise me if one could reduce the sensitivity/vibe transmission by 50% and STILL feel more just by virtue of larger surface area and more/better contact with hand parts. Sometimes how something measures and how it functions relative a human are two vastly different things. Rigid foam arbors which bridge the space to larger contact areas are a good thing for me and strike detection.

Rods got skinnier butts over the years, I reckon it's more than a passing fad. One can only curl a large hand around skinny blanks so well, and not very well at that.

If we get back to practical results, a foam core, carbon skinned grip is just as sensitive as directly blank contact. The difference between the two is so minute as to be beyond the ability of a human to discern it.

...........