Couldn't find the info I want so starting this. Assuming the guides and tip top have been placed in optimal position, I imagine that the tip top receives the most stress/pressure when the rod is bent. The guides on the parabolic receive fairly evenly distributed pressure and the butt guide will be the least pressured. Does anyone know of any tests already done as this can't be new?

If the rod is bent (as in a fish fighting position) and the tip section is pointed towards the fish, why would it have to most stress/pressure on it?

My guess is that the tip is stressed the least as it is at the most flexible point of the blank. The rest of the load is distributed across the remaining guides.

I would think the load increases on each guide closer to the butt with the greatest load placed on the spool of the reel.

This is just my intuitive take on the matter.

Would like to hear a mechanical engineer's response.

You'd have to define what you mean by "stress" in this instance. If you're talking about the portion of the blank that carries the most load, then it won't ever be the tip. If you're talking about flex, then keep in mind that as you apply more and more load to the rod, and assuming we're talking about the rod being used properly, the flex in the rod will move towards the butt with the upper area straightening out.

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I agree with Dave - except that I would think that the max stress is mid rod. Least at the tip and butt guides. Fish and reel sharing equal load.
Herb

Ken,
Stress is the value of load versus the amount of material to handle the load.
Max stress is initially in the tip.
Rod deflection keeps this stress from rising to it's failure level.
As the rod deflects the stress in the tip is allowed to be shared deeper onto the blank where more material is available to distribute the load.
Maximum load on the guide train is where the blank is stiffest.
If the guide is allowed to deflect by the blank the load can't rise.
Load direction will also come into play .
If the load is straight with the blank there is no stress or deflection.
If the load is perpendicular to the blank the stress and deflection will be based on the blank taper.
The change of taper is where max stress levels will occur.
If possible place guides adjacent to these taper changes on the butt side of the transition.
This will require a detailed measurement of the blank taper and weight distribution.

Eugene Moore

The stress on the tip must be greater because the tip top ring always wears first and more than the guides do.

The tiptop receives more wear because the line is at its greatest angle across the tiptop. The tiptop also serves as a "wiper" for removing most of the minute dirt and grit that is attached to the line as it's retrieved from the water.

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I think that Mr. Kirkman really nailed it when he indicated that the tip is the "wiper" for the rod.

In many fishing conditions, there is a huge amount of "junk" that gets picked up by the line.

Some lines are more susceptible to picking up "junk" than other lines.

Especially, when the "junk" is abrasive, like mud, or dirt laden moss, or dirt laden cotton from the trees; the tip does the wiping of the line as it is reeled onto the rods.

I think that under normal clean line conditions, it is a very rare tip or guide that ever shows any wear.

Conversely, under dirty or abrasive conditions, it is possible to have wear showing up on the the tip and or guides and the continued sandpaper action of the dirt laden line continues to scrub across the tip and guides.

Be safe and fish with a clean line.

Roger

Actually the reverse is true. dynamic testing show this.

Correction, I intended to say load or force. the load increases from tip to butt at each guide.

Eugene, thanks for your explanation. I did mean loading so stress was appropriate. You say the max load will be where the blank is stiffest. I am in the middle of putting a new butt guide on a rod and found that with the reel on and putting the line thru the guides and attaching the line to a pole and bending the rod the butt guide's load was not a lot. To me this meant that most of the load already was taken up further up the rod, which by the way, is a medium taper.

I have seen some test results. IIRC maximum load wasn't the butt guide but the over the next two or three guides towards the tip.

IMHO load (alone) isn't the whole picture. As Tom pointed out, consider the angle of the line across the guide. If I decide to spend extra (for a higher quality guide) it is the tip-top first and the butt guide second. The angle across them is the highest.

Russ in Hollywood, FL.

Ken,
I could be mistaken but, I believe what you are seeing is rubbing friction due to line tension and rod deflection.
As the line is tensioned and the blank rotated, the line forms a series of straight lines thru the rod arc.
In between these straights the line is bent around the guides.
This creates an area of contact around the guide rather then a point of contact. This also reduces guide contact stress.
Since the guide, in most cases, is a fixed bearing this allows friction to increase.
The load may be small but the area of contact increases as the angle between adjacent guides increases creating rubbing friction.
The tip top sees the most angular deflection, hence the greatest area, and the most friction even though the load is low.
The butt guide experiences the highest load but the least angular deflection minimizing friction
Since the rod deflects greatest at the tip the rubbing friction will always be highest in the tip area.
All the guides on the rod are capable of bearing load. The effects of each are dependent on the others. As each guide is relocated it has an affect on every other guide on the blank.
Blank taper is at the manufactures control along with it's deflection characteristics. Angle of deflection and line tension are angler controlled. Stress is a function of load and area of contact. Friction is a function of load and contact area.
The wrapping of the line around the guide reduces stress at the expense of increased friction.

Hope this wasn't too painful.


Eugene Moore

There is one other element to this equation. The psi applied to the guide ring, by the line. The more the angle of the line across the guide ring, the larger the footprint, resulting in less psi applied to the ring. Yes, these are very very minimal values, but they are part of the equation.