Probably just a little bit of overkill, but... just yesterday I started playing around with a spreadsheet to calculate the center of mass (fulcrum) for a rod. I'm a bit of a math and Excel geek. What I've have so far will account for blank, handle, butt/cap, and guides (median) to get a center of mass for the "fixed" components. The reel and reel seat get counted as a single unit. So far the spreadsheet will simply tell me where the center of mass ends up as I move the reel/seat forward and back. What I plan to figure out is how to specify where I want the rods center of mass in relation to the reel/seat (this would be the distance from the spinning reel foot to my index finger as I grip the rod for casting; 2.5") and then the spreadsheet would calculate how far back from the handle tip would be the beginning of the reel seat (or how much weight needs to be added to the butt). I'm only thinking spinning rod here but I'm pretty sure it could be modified for fly rods and casting rods. I'm sure there will be things I forget to account for but I'm combining two passions :)

Center of Mass = ( d1w1 + d2w2 + d3w3 + d4w4 + ...dNwN ) / ( w1 + w2 + w3 + w4 + … wN )

1, 2, 3, 4 .. N = component 1, component 2, etc. through the Nth component
d = distance from reference point (rod butt) to the center of mass of the component
w = component weight

Notes:
1) All weights should be in the same measure (ex. ounces) and all distances in the same measure (ex. inches)
1) A 12" straight cork handle would be measured as 6" from the butt.
2) Taking out a chunk of the handle at the fulcrum (blank exposed) will have no effect on the location of the fulcrum.
3) Fore grip and rear grip can be counted as two components
4) "Distance" for the blank is a measure from the butt to its balancing point.
5) "Distance" for the guides (counted as one component) may be able to be calculated as an inverse function of the rods balancing point.

Jim Hicks

Joe said: >> You would need to either model the blank, or experimentally find the center of mass of the blank and include it in your calculation

See Note 4: "Distance" for the blank is a measure from the butt to its balancing point.

For whichever blank you're using you would balance it on your finger (or whatever) and measure from the butt to that point.
If that point is 30" and the weight is 0.7 oz and the blank is component 1 then d1w1 becomes 30 * 0.7
All individual components would have their "distance" calculated as a measure from the butt to their individual balancing point.

Balancing at an angle would be difficult. In physics the rotational force of a counterweight would apply until counteracted by an opposite force. If you move the fulcrum forward of the center of mass then the butt goes down and keeps going down until the rod is verticle. Inertia would have it continue around until gravity pulls the butt back. You now have a pendulum. In reality it works differently because you're using something relatively big like a finger to balance the rod; as the rod rotates it contacts the finger at different points and the fulcrum changes. There's also the individual grip which may have the palm applying force in one way or the other. If you start with parrallel to the ground then the math is simple. The variable for offset from the reel/seat would be an individual preference that can be adjusted for the individual grip and angle desired. This variable should be pretty constant for each persons grip.

Overkill!!!!!! That's rocket science!! LOL Way out of my league.

Bill in WV

By the time you’re done calculating. I'll be on the next rod with both of them balanced.

I don't mean that in a disrespectful way. Just seems like a lot of work just to get at an equation that can be derived from sliding a few components back and forth. Especially with so many variables like guide sizes and materials, and depending on the differences in the actions of even identical blanks guides might be a little this way or that.

Then there’s the variable of the differences (even though slight) of the amount of epoxy on each guide

I would still be interested to see what you end up with and if you can develop a practical application for it.

Here's some test data. The lines with an asterisk (*) are where you would need to enter a number.
I want to figure out how to get it to calculate the "With Reel located at" line.

Component Length Weight (Oz) CoM
*Rod 68.00 1.20 28.00 <balance point of the rod
*Handle 12.00 0.50 5.50 <balance point of handle
*Butt/Cap 0.00 0.50 0.00 <balance point of Butt/Cap
*Guides 0.10 40.00 <balance point of Guides (est)
Total Components Weight: 2.30
Total Components Center of Mass: 17.65
Fixed CoM is 5.65 inches ahead of the handle tip

Component Length Weight (Oz)
*Reel 6.00
*Reel Seat 3.00 0.50
Total Components Weight: 6.50

*Offset desired from Reel to CoM: 2.50 <adjust for personal grip
*With Reel located at: 8.00
Total Components Center of Mass: 10.52

The reel seat should start 2.50 inches back from the handle tip

James,
I think what you have done is interesting and frankly I am still thinking about it but I have a couple of points that you might want to think about.
1. The fulcrum and the center of mass are not necessarily the same. In many if not most fishing situations a rod is actually a class 3 lever not a class 1 lever which means that the fulcrum is actually the butt of the rod.
2. I think that calculating the moment of inertia might be more useful. How a rod feels in use is not really a function of the center of mass, or even the static balance point. It is more a function of the inertia and the inertia is naturally a function of both the mass and the velocity.
3 I think that adding weight to the butt of the rod to statically balance the rod does not really accomplish what many rod builders are attempting to achieve because of #2. I do not see a static balance as being of much use. What you would really like to accomplish is to dynamically balance the rod. Plus adding weight also reduces the sensitivity of the rod.
A perfect job of dynamically balancing would require including the affect of the terminal tackle but even without the affect of the terminal tackle I think that it would be a better indicator than a static balance.
4. I do not understand how this is useful in positioning guides because it does not take into consideration the rods action.
5. If I understand what you are trying to accomplish I would also make the point that where the mass is on the rod is as or even more important than the amount of the mass. The affect of the mass on the rods resonant frequency increases roughly exponentially as it is added closer and closer to the tip of the rod and resonant frequency is arguably the most important property of the rod.
I say again, what you are doing looks interesting and also looks like fun.

I was just trying to calculate the reel position in order to get a comfortable balance while holding the rod (unfortunately I do that more than landing fish). I don't believe I've ever noticed the static balance of a rod while casting or fighting a fish. You are correct in that casting and fighting a fish should be considered in the design of the total rod. I believe those activities demand good positioning and shape of the handle so you can get proper leverage as the rod becomes a class 3 lever (and still work the reel too). Most rods will have a range of lure weights that they are optimized for and perhaps that can be used to optimize positioning and contouring of grips for a cast. Then again the positioning would depend on the length of the casters arm. The type of fish, their potential resistance, circumstance of hook set, and angle of retrieval could also be roughly estimated for a general rule to determine leverage points. Arms length comes into play again. It seems to me that over the years trial and error have already done most of the work in that rods that work well for certain types of fishing have developed their own traditional styles. I will look at the dynamics of the cast and retrieve and if the numbers suggest something that deviates from the norm then I may just have to build one to see if it really works. Perhaps a two handed casting grip with a fighting foregrip. Who knows, I may come up with the next best thing since the acid wrap!

And, yes, it's fun too!!

Jim,

I'm sorry that I missed the designation for the blanks center of mass. After posting, I realized that you could use the static balance point of the rod and use that.

A spinning rod can be made to balance at an angle, because the center of mass is off of the axis of the rod. So long as the center of mass can be made to lie below your hand, the rod can be balanced at an angle.

Emory,

I would love to sit and pick your brain sometime. I have read some of your insights into rod building and am quite intrigued. I'm sure that as I read them and have questions, I'll ask.

Joe

Joe,
Maybe we will get a chance to do that. I am sure that I would enjoy it and no doubt learn from it as well.

>>So long as the center of mass can be made to lie below your hand, the rod can be balanced at an angle

You got me there! I'm treating the rod as a simple line rather than as a three dimentional object. The simple static balance would still work and the grip variable would easily adjust for an angle preference but that variable would be trial and error which is what I'm attempting to limit in the first place. To account for the offset center of mass created by the reel you would need the center of mass of the reel in three dimentions and the whole project gets much more complicated. I think I would need to get this to work in Excel or possibly a hand calculator, with minimum user input, in order to make it competitive with dry fitting.

Emory,

This is a joke and hope you take it as such. But, I wish they hadn't opened up that closet we had you locked in. You guy's make my head hurt!! I have a decent IQ, but this stuff is way too technical for me. Enjoy yourselves, I'm outta here!!

Bill in WV

Bill,
I think that it is just a question of different people having different interests. I thought that Jim's approach was interesting and thought provoking. But if posts like those above do not interest you that is fine you can just ignore them. Posts on things like one more type of chevron or diamond wrap or the colors used bore the heck out of me. I like vanilla ice cream you probably like strawberry. I will not try to p-- on your strawberry if you will not p-- on my vanilla.



Edited 1 time(s). Last edit at 08/08/2007 10:50PM by Emory Harry.

Deal Emory!! That's why I said " Enjoy Yourselves!! " Like minds are good company. Just trying to wax humorous, maybe I shouldn't do that.

Bill in WV



Edited 1 time(s). Last edit at 08/09/2007 03:12PM by William Bartlett.

Bill,
Don't worry about it. I was not offended. I will try not to mess with your strawberry if you try not to mess with my vanilla.

I am in the middle of a 12 rod project for a bass fisherman. All rods different techniques. His demands are light, premium blanks and components and balanced at front of reel seat before reel is installed. When he talks his words say that a balanced rod is more sensitive and that he wants maximum ability to "feel" bait action and fish bites.

On the 92 inch flipping sticks, Lami 927 F, with a 10 in split rear and fully exposed reel seat it requires 2.25 ounces of counterbalance in the butt cap. The construction is light with Alconites spiraled, no foregrip and Perma Gloss finish. I am building these rods so that the weight is easily detachable. When he checks these rods with a reel in place he holds the rod in a horrizontal position. His explanation is that he can feel movement a lot better with the rod balanced and his hand, wrist and arm are not exerting forces to hold up an unbalanced tip.

He reads this forum and I really would apprecitate any comment. I would think that if Emory is correct about weight effecting sensitivity this would be the place. Is the blanks sensitivity the issue in question in the real world or is it the sensitiviy sensations that the fisherman can detect that really matters? Is it a mistake to add that much weight to balance a rod?

I am rigging this thing where he can fish with it early in the day without the weight and later if he gets tired he can easily pop on the weight.

Thanks



Edited 1 time(s). Last edit at 08/10/2007 09:05AM by Bill Stevens.

Bill,
If the rod is held in the horizontal position as you describe so that the line is coming directly through the guides to the reel the sensitivity will be mainly a function of the total inertia that results from the total mass. Inertia is the resistance to movement, Newton's second law of motion. The higher the mass the more inertia the rod will have and the less sensitive the rod will be. If your customer wants the maximum sensitivity you do NOT want to add weight to balance the rod. The added weight naturally increases the mass which increases the rods inertia which will DECREASE the sensitivity.
As the tip of the rod is raised then naturally the other characteristics of the rod, mainly its stiffness, come into play but when held horizontally the sensitivity is almost totally a function of the inertia that is determined by the total mass or weight.
I would suggest to the customer that he wants to keep the rod as light as possible and use as light a reel as possible. The reel will usually contribute as much mass as the rod does and therefore when the rod is held horizontally will have as much affect on sensitivity as the rod.
Another thing to consider which will have a large affect on the sensitivity is the line. How much of the energy in the fish's bite that gets to the fisherman's hand is also a function of the elasticity (stretch) and mass density (weight) of the line and the tension on the line. Pound for pound braided lines have a much lower mass density and much higher elasticity than monofilament and therefore transmit much more of the energy in the fish's bite to the fisherman's hand. Plus many people forget about the tension on the line. Different fishing techniques naturally result in different line tension but the more tension on the line the more of the energy in the fish's bite will get to the fisherman's hand. If the line is slack it makes little difference what the characteristics of the rod are. With a slack line there could be a whale pulling on the end of the line and the fisherman will not feel it until the line tightened.

One More Emory: The bass fisherman just saw your post at work and called me. His comment was he holds the non stretching line between his fingers for his "primary sensitivity" in bite detection. In his mind the detection of tip vertical displacement, by sight, is secondary. He says a balanced rod weight releives him of muscle strain in the off hand. Is lure feel and motion detection, with tip usually down, significantly effected by butt weight.

Go Between



Edited 2 time(s). Last edit at 08/10/2007 04:03PM by Bill Stevens.

Bill,
I am not sure that I understand exactly what it is that you are asking but added weight has a significant affect in any case.

Emory,

What Bill is saying is that the angler palms the reel with the line lightly pinched between his thumb and forefinger, while holding the rod roughly perpendicular to the line. The angler then can feel the longitudinal signal coming through the line, as well as, the transverse signal coming through the rod. While palming a reel, a tip-heavy rod can feel unwieldy. This can put a strain on your wrist and forearm after handling the rod all day.

What the extra weight provides for the angler is a rod that feels less tip-heavy, and therefore requiring less effort to keep the tip up while working a lure. An added "feature" is that when aggressively hopping a bait, the rod imparts a larger impulse to the lure, causing it to hop further off of the bottom. The angler may want be willing to be willing trade off the sensitivity decrease by increasing the inertia of the rod, for the comfort gained by not having to hold the tip up all of the time.

I may have to look it up again, but I think you said that adding weight exponentially affects the rod, as the weight is added in the tip section. So by balancing a properly designed rod, the angler gets the significant gain in sensitivity from a light tip, but gives back a hopefully lesser amount of sensitivity by adding weight to the butt. Thus, resulting in a more sensitive rod than is available in a factory model.

In handling one of my friend's balanced BPS rods, the tip does feel light while working the lure, but one handed casting can be a pain with all of the extra inertia.

This is an example of how much a "Truely Custom Built/Designed" rod matters to diferent fisherman. Guys that are deeply invloved in the technique of flippin, have their very each to his own opinions about the way they want a rod to perform when flippin for hour upon hour. Some of them want a rod perfectly balanced, some want them a tad butt heavy, some want them a tad bit tip heavy. Here again, this is truly where a custom builder comes in and can shine with his services. I know of fellows that are so into flippin, that they may have not only one, but several flippin sticks in the boat, with different baits and just pick up one with a different lure instead of re-tying each. They may also want each rod to have just a little different feel to it, for each type of different bait they may be flippin. That 's the reason that I go by the theory of, 'Whatever Makes Them Feel Good About What They Using", is what we should produce for them and make sure the rod we build for them, pleases them and their style. If they feel good about the way their rod feels and performs, yes they will definately be more tuned into catching fish and that is the bottom line. Guys that do a tremendous amount of flippin are a different breed of cats and are very particular about how they want their rods to be set-up and feel. I am a firm believer of balance of a rod. I try to balance as much as I can by adjusting the reel up and down the rod a bit. Sometimes the reel can be moved up or down by a 1/4", 1/2" or 1" or so, etc., and help create balance and not have to add weight. This is where using the split grip handle system makes it easier to achieve this. I know my post may not be right in the mix of some of the others above, but just my take on this issue. I guess that I still do the balance act by temporarily fixing the reel seat to the blank, with the reel to be used in the seat and taping the guides on. As I mentioned earlier, I simply then move the reel seat postion and reel, up or down a little to gain my balance or the feel of the rod to be that of what the customer wants or in my case, the way that I want it to feel. Adding weight to gain feel of balance is my last resort, but I will do so if it is definately needed.

Bob McKamey





Edited 1 time(s). Last edit at 08/10/2007 05:02PM by Custom Tackle Supply.