Fly rod design

[bobtheflounder]

I just read Paul's FP from Monday and it got me wondering, how do companies like Sage, Scott, and Loomis design their rods?
I've heard mandrels are very expensive, do they stick with the same mandrel throughout the evelopment cycle and just vary the graphite layup, or do they make new mandrels with every revision? And how do they even know what taper on the mandrel to use in the first place?

How was the process for you Paul?

[Paul Arden]

Hi Bob,

They most certainly use a single, tapered mandrel. The thickness of the carbon wall comes from how the cloth is cut. Imagine a quadrilateral, wider at one end than the other, when it is rolled there is more carbon at the thick end. Sometimes different carbons are mixed - there are three of four types in the HT and another for ferrule reinforcement. I've watched the process a few times with several manufacturers and it's always the same.

My involvement in the design process is not from this side of things - that would see me in a factory cutting cloth, albeit in a rather nice part of the world in Asturias in Spain - instead I cast the rod, take it fishing, live with it for months at a time, put it through many people's hands, thinking about how it could be better. Mostly this means where to make it stiffer or softer, faster or slower but it takes me a long time to decide and then I have to compare that rod to the previous. It took me two years to decide how to change the 7'6 3/4 (and now I have two rods and I can't decide between them!). Mine is the process of tweaking from whatever starting point. The HT8 took 7 or 8 prototypes (the last three were to try to stabilise the tip). The HT10 was done in 3. We manage to break quite a few rods too, this is done in Shootouts and enables us to find weaknesses.

No doubt the other end of the process is considerably more technical. Whenever I ask Alejandro a technical question I get a technical answer. I'll run it past him. A couple of articles on rod (blank) design would be a great idea and I'll try to put something up in the next few weeks.

Cheers, Paul

[Merlin]

They most certainly use a single, tapered mandrel.

Nope , or only for cheap rods.

For a modern 4 piece rod with sleeve over ferrules, you can have up to four different mandrel slopes, a number of types of carbon fibers of various resin content and fiber areal weight. That's a different world from cane rod manufacturing.

Design comes from experiment mostly, with some help from softwares if needed. In the case of cane it is possible to start from scratch with a suitable calculation file, providing you know what you are aiming for rather precisely in terms of rod characteristics (line size, action, speed, etc.), and providing you know the characteristics of the cane you are using.

You can also take inspiration from competitor's rods, it is not so complicate to estimate their design.

Looking forward reading articles on that topic.

Merlin

[Paul Arden]

For a modern 4 piece rod with sleeve over ferrules, you can have up to four different mandrel slopes

That’s interesting. I was going by what I learned many years ago I when I visited David Norwich. I can see now that I’m going to have to widen my research! I remember David telling me that there was a time when mandrels had differing slopes but that most used a single slope “nowadays” - nowadays being about 20 years ago.

It’s certainty another variable. I can’t imagine that anyone makes a new mandrel between prototypes however.

Cheers, Paul

[bobtheflounder]

They most certainly use a single, tapered mandrel.

Nope , or only for cheap rods.

For a modern 4 piece rod with sleeve over ferrules, you can have up to four different mandrel slopes, a number of types of carbon fibers of various resin content and fiber areal weight. That's a different world from cane rod manufacturing.

Design comes from experiment mostly, with some help from softwares if needed. In the case of cane it is possible to start from scratch with a suitable calculation file, providing you know what you are aiming for rather precisely in terms of rod characteristics (line size, action, speed, etc.), and providing you know the characteristics of the cane you are using.

You can also take inspiration from competitor's rods, it is not so complicate to estimate their design.

Looking forward reading articles on that topic.

Merlin

From the videos I've seen, Gloomis still uses a single tapered mandrel for a rod, although I bet many other companies do too for some rods. It was interesting to note that they sometimes reused different mandrels for new rod series. I remember reading somewhere that many company's mandrels were very similar and the main variable was the graphite layup (maybe it was Andy Dear?).
Scott definitely does not have a single taper, at least for the Radian. I also think the tapers on a single mandrel can be compounded nowadays, so that a 4 pc rod could have more than 4 different tapers. And the rolling tables can adjust for multiple tapers as well. Some golf shafts even use a curved taper.

I wonder how much computational analysis the bigger companies like Daiwa, Shimano, and the big Asian OEMs have to design their rods, and how much it really helps over the smaller companies. In the carp world many of the boutique rod makers are held in higher regard (although some of it is definitely snobbiness) than big companies and in fly fishing I guess almost all companies are boutique except for Hardy and the other similar rods that come out of that factory in Korea.

Can the cane rod design software be adapted to graphite rods?

[Merlin]

Hi Paul

As far as I know, there are four different slopes in the HT6 (mandrels).



Merlin

[Merlin]

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

[Paul Arden]

It’s certainly possible. I first visited David Norwich about 17 years ago because his Evolution 2 5WT 2-piece was the best I’d cast of any manufacturer. I was keen to get involved to produce the Hot Torpedo range - yes I had the name back then but thought the colours should be that of an aubergine.

It was there that I was shown the blank wrapping process - DN was using single slope mandrels. The reason we haven’t produced a 5WT is because we haven’t bettered that. At the time I asked David to produce a 4-piece version but that was a completely different rod and not in the same class. At the time I couldn’t afford to go down the path of producing multiple endless prototypes in order to get the end result I wanted. So the project sat on back-burner for another decade.

I knew Alejandro from the same time but he wasn’t involved in the rod business. Ten years later we sat down and discussed my requirements. Finally I found someone who I knew could produce the rod I wanted because the third prototype of the HT6 was - fortunately - bang on. Of course we broke that one and had to make a better one!

Hmmm just been hit by lightning. No power!

Cheers, Paul

[Viking Lars]

I remember that Norwich 5-wt - that really was an excellent rod. Didn't you also have one with interchangeable sections that made a 5-wt 6-wt or just a stiffer 5, or something - a 4-piece?

Lars

[Paul Arden]

Yes I did, but it didn’t compare to the 5. The 4-piece was still pretty excellent but not exceptional compared to other rods around. That 2-piece 5WT was in a class of its own.

Cheers, Paul