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## Fly rod design

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bobtheflounder
Posts: 16
Joined: Tue May 29, 2018 11:27 am

### Fly rod design

Merlin wrote:Hi Bob

To my knowledge Loomis has been bought by Shimano years ago and although I have never measured a NRX I would bet there is not a single slope in this rod.

Everything is possible like reuse of older mandrels, you are right in saying that sometomes tips have a "compound" mandrel, so that makes another extra slope possible, or even two. All those techniques are not knew, I would say that they have been in use for 15 years or something like that.

I can imagine that companies like Shimano are using design softwares, Hardy was producing antenna in the past and I remember seeing computerised rods. The problem is not the computing software, it is to define what you are looking for in terms of performance, and for me that always ends in actual testing. Computing also assumes that the mechanics of rod casting are understood, and I do not know of any published information on that, mine apart. For sure you can fine tune a ferruling system with suitable software for example, but is it really necessary given manufacturer's experience?

In 2006, whilst I was inquiring about rods, Shimano answered my letter to Loomis (then I understood they had bought Loomis), and just asked me if I was ready to give them my technical knowledge for free (all would become Shimano patents). You can guess my answer.

Calculating cane rods is easier since the material is "always" the same, especially if you start by a solid rod which you hollow with inspiration afterwards. I did that a few years ago and I have a spreadsheet for solid cane rods design. Such calculation gives you a straight "master" profile which you can fine tune afterwards. I have a synthetic rod version but it cannot handle multiple modulus and tapers, that would be too complicate.

Merlin
This is the video I was talking about for Gloomis. I am not a fan of Shimano as well, and by the looks of it the marketing BS has spread to Gloomis with their Asquith. Aparently the "Spiral X" process that has been used for years by others is now "exculsive and patented".
I guess they could vary the flag taper/wall thickness to get a compounded action?

The uses a hypothetical software could be used for optomizing dampening (what if Paul didn't have to do the last 3 HT8 prototypes and instead used software to test one) and maybe sensitivity for lure rods by measuring how well a rod transmitted vibration. And also optimizing the internal taper and layup for a specific action. I think some manufacturers have enough resources/budgets to epxeriment with other aspects like how the S curve at the end of the cast affects performance and other stuff I read on this forum that I don't really understand .

For the ferruling sofware you mention, how does that work? Are you just adjusting taper/wall thickness and the resulting stiffness for differing diameters?

What are you calculating for with the cane rod design? Action and stiffness? I would think with todays smart/generative design tools it would be possible to make a complete rod design software. The golf industry must already have something like it, as their design process and performance parameters seem much more scientific.

Merlin
Posts: 1288
Joined: Wed Jan 09, 2013 8:12 pm
Location: France

### Fly rod design

Nice video Bob, thanks.

Nothing specific, on purpose I guess, but Steve does mention the variability of factors (material FAW, resin content and a thousand mandrels!). He uses the example of a one piece rod (spinning likely) which allows not commenting ferruling in details, fair enough.

I mentionned the possibility to fine tune a ferrule but I do not use such software myself. I use various home built software which were challenged against pro ones in a laboratory of a world size OEM. A discussion about dampening took place with the lab, but when they told me that the weight of the blank would likely double with the damping device I stopped there. The Orvis patent is an example of a smart approach but in such case, everything is dampened, including the main rod response. No success to anticipate. There are other reciepes to deal with high frequency vibrations.

For cane, you have to define rod length, line size, bending type (butt, mid, tip), you can tune material characteristics if needed and include metallic ferrules if you wish. The speadsheet shows the action category the rod belongs to (graphic), gives an estimate of rod stability, and calculates unloaded and loaded speed for the line weigth among other parameters. You can play around with figures and rediscover the basic rules of rod design: what happens if you lengthen the rod, change the bending shape, etc. This spreadsheet is not confidential, you can have it if you drop me a mail adress in a board message.

Merlin
Fly rods are like women, they won't play if they're maltreated
Charles Ritz, A Flyfisher's Life

Paul Arden
Posts: 11955
Joined: Thu Jan 03, 2013 11:20 am
Location: Belum Rainforest
Contact:

### Fly rod design

I suspect that most rod ranges that are replaced by newer rod ranges are simply variations upon the previous range and that this is done across the range without each rod being built from the ground up! Certainly the hard work was done many years ago by most companies.

Ferruling is interesting, because there is a great deal of handy work involved when fitting rod sections. The reason It's not possible to send out mid sections for example is because each section is hand fitted using glass paper to make the perfect fit. I remember about four years ago getting three quite different HT8s - the difference? Different sanding options!

Mind you, if it's not possible to make two fly lines the same weight, in a machine-only environment, then you can see why there are variations between identical rods that should be the same. Whichever way you look at it, there is still a craftsman involved in producing graphite rod blanks.

Cheers, Paul
It's an exploration; bring a flyrod.

Flycasting Definitions

bobtheflounder
Posts: 16
Joined: Tue May 29, 2018 11:27 am

### Fly rod design

Merlin,

The Orvis patent was just my example that rod manufacturers are actually doing some more advanced R&D (which i guess you already know). I feel like some people don't give them enough credit sometimes (i know I didnt).

Is your spreadsheet similar to the other cane rod design softwares around? I would love to play with it at some point but I already have enough projects right now and don't want another distraction!

Paul,

Some companies grind the male sections of the ferrule to ensure a perfect fit everytime.

Paul Arden
Posts: 11955
Joined: Thu Jan 03, 2013 11:20 am
Location: Belum Rainforest
Contact:

### Fly rod design

Hi Bob,

Indeed! That’s why replacing broken sections that aren’t the tip is so complicated; each section is custom fitted.

Cheers, Paul
It's an exploration; bring a flyrod.

Flycasting Definitions

Merlin
Posts: 1288
Joined: Wed Jan 09, 2013 8:12 pm
Location: France

### Fly rod design

Bob

It is much simpler than RodDna and without shortcuts. It is easy to use and you can learn design basics from it.
I have another file which allows applying a given design on a rod of different length and line size, but it is not available for playing with. However, I can run it on request (free of charge).

Merlin
Fly rods are like women, they won't play if they're maltreated
Charles Ritz, A Flyfisher's Life

andrewparkeruk
Posts: 144
Joined: Wed Jan 09, 2013 10:49 pm
Location: Manchester, UK

### Re: Fly rod design

Interesting video Bob, thank you.

Most of those mandrels look to be finished rod length. I didn't pick up from Steve Rajeff's commentary whether multi piece rods, eg. 9' #5 4 piece, are rolled on four mandrels; or if the mandrel produces a 9' rod which is chopped into four pieces, then jointing pieces added. I suspect the former.

Andrew

Merlin
Posts: 1288
Joined: Wed Jan 09, 2013 8:12 pm
Location: France

### Re: Fly rod design

Andrew

Cutting a single blank into four pieces means that you are going to use spigot ferrules, not sleeve over ones. And since most rods have sleeve over ferrules today, you can guess what happens.

Merlin
Fly rods are like women, they won't play if they're maltreated
Charles Ritz, A Flyfisher's Life

Mangrove Cuckoo
Posts: 200
Joined: Tue Jan 29, 2013 7:51 am

### Re: Fly rod design

Curious note:

Years back, I had an opportunity to ask questions to an Orvis employee that had given a seminar on rod design. This was when Helios 2 was hatching. The show was in S. Florida, so a lot of interest was on tarpon rods, specifically one-piece rods as they are favored by the high-end tarpon anglers.

His statement was that big \$ were involved with one piece rods since new ovens greater than 9' had to be installed to cure the blanks.

I do not remember if he said it, or if I just assumed it, but the takeaway I took was that most flyrods were cured as sections. I remember it specifically since I had always thought rods were created whole, then cut into sections and the ferrules added afterward.
“Very simple man. Catching fish makes me happy. Scaringly simple.”

Håvard Stubø

crunch
Posts: 126
Joined: Sat Feb 02, 2013 6:58 am
Location: Kerava, Finland

### Re: Fly rod design

I think that technically it is possible to build sleeve ferrule blank using mandrel which is shorter than the target rod will be building two blanks which then are cut so that pieces fit. Naturally there comes more waste and it might be too complicated to mass produce blanks that way but for hobbyist one piece mandrel could be fine.

Esa