Garrison stress curves, data source?

Re: Garrison stress curves, data source?

feeds@yuku.com (hoagy b carmichael) — Fri, 17 Jul 2009 17:23:05 GMT

Hello: CORRECT. Garry was actually more interested in the development of his rod tapers, and the working of the bamboo, than he was in the craft itself. That was a means to an end, but "tweeking" was in his nature, and was very much the spirit of the man. He did develop the original rod tapers while laid up in the hospital with a nervous condition, and many of those stress curves, to him, proved out his tapering formulas. When nylon lines came in around 1946-7, he went back to work...

Re: Garrison stress curves, data source?

feeds@yuku.com (mer) — Sun, 14 Jun 2009 06:58:11 GMT

fishbum wrote:
...you run head long into the fact that you must know the stresses before starting a rod design. I have no problem with finding moments for a general rod with a linear taper to start things off. I do find a problem with the process when we get to the part of applying stresses to get to diameter. Somewhere these stress were calculated beforehand and that part of the process is not in the book. Like I said in my...

Re: Garrison stress curves, data source?

feeds@yuku.com (BigTJ) — Fri, 12 Jun 2009 16:07:34 GMT

OK Fishbum I see where you are coming from, and I think I have an answer. Let's to a thought experiment. Say we could send Garrison back in time with all his knowledge to the time at which only 5 bamboo rods had been made. Garrison could do his moments analysis on these 5 rods, and compare stress curves on each. The stress curve is used in design as a numerical evaluation of the general bending characteristics of each rod. Then, for forward design, Garrison could mix and match or create...

Re: Garrison stress curves, data source?

feeds@yuku.com (Tom Smithwick) — Fri, 12 Jun 2009 12:24:53 GMT

Hi Fishbum - I believe you are chasing something that does not exist. Good flyrod tapers are designed by people who have cast a lot of rods, and know what they want a taper to do. Garrison's method is tool to get you there, just like the time honored thickness chart method. The advantage to Garrison's method is that once you have designed one rod that suits you, it becomes easy to develop a series of rods of different line weights and lengths with similar casting characteristics. I...

Re: Garrison stress curves, data source?

feeds@yuku.com (fishbum) — Fri, 12 Jun 2009 11:16:16 GMT

BigTJ wrote:
That's what Garrison did - broke down all the little moments that add up to the bending stress that ultimately describes the theoretical arc a rod is bent into.

So from the information given from the moments and bending stress we should be able to calculate the deflection of the rod. Is that not right?

It seems to me we are chasing our tails here. If you do a flow chart of the rod...

Re: Garrison stress curves, data source?

feeds@yuku.com (mattcliff) — Thu, 11 Jun 2009 12:39:38 GMT

After breaking my own Heddon at the described location last year, I checked the rod's stress curve which I had graphed when I bought the rod. Turns out there is indeed a hump in the curve just below the upper set of ferrules, which made me think perhaps the curves do bear some relation to real-world stresses on a rod.

Re: Garrison stress curves, data source?

feeds@yuku.com (OldCanerods) — Thu, 11 Jun 2009 12:27:49 GMT

If you look at a tip under load (fish on) you will notice that the tip near the tiptop is pointing towards the fish and so the load is not likely to break a tip. Tips are more likely to break when a fly is stuck in a tree and the fisher yanks the rod sideways to free the fly. (A major no-no) Plus as a collector of Heddon rods, I find that many Heddon rods are found broken at the female ferrule of the mid section, a point of high stress, limited ability to flex due to location near the...

Re: Garrison stress curves, data source?

feeds@yuku.com (BigTJ) — Thu, 11 Jun 2009 01:08:06 GMT

Fishbum,

I didn't directly answer you questions. Here are the simplest answers I can think of to each of them:

1. The data come from the dimensions and physical characteristics of the fly rod being analyzed and are based on the assumptions that Garrison made.

2. The data are generated by fairly simple functional relationships between the dimensions of the fly rod and how those translate to the bending stress experienced by the rod.

The Garrison...

Re: Garrison stress curves, data source?

feeds@yuku.com (BigTJ) — Thu, 11 Jun 2009 00:47:46 GMT

It does not seem to me that a professional engineer would set out to design a fly rod by drawing a curve on a piece of graph paper that represents data

I am a professional engineer and although I don't use graph paper if I had been practicing in the 30's like Garrison then graph paper is exactly what I would have used. We have EXCEL now but back then that's what they used. In fact I can't really think of another way an...

Re: Garrison stress curves, data source?

feeds@yuku.com (john channer) — Wed, 10 Jun 2009 23:17:08 GMT

Read the book, it's all in there. The graph comes from the stresses he calculated, very painstakingly, with a slide rule. Garrison figured the moment of inertia of the bamboo itself, the line guides and ferrules for every 5' the full length of the rod, 3 TIMES. The first time is based on an assumed straight taper, the other two are to correct the errors in the first caused by the accumulation of extra weight of the additional guides, ferrules and line as you get closer to the butt. He...

Re: Garrison stress curves, data source?

feeds@yuku.com (Lewis B) — Wed, 10 Jun 2009 23:01:39 GMT

Its my guees that what happened is that after alot of trial and error, good tapers were developed and the he reversred engineered his findings. However I would like to hear from other folks as to thier thoughts on this Lewis

Garrison stress curves, data source?

feeds@yuku.com (fishbum) — Wed, 10 Jun 2009 14:35:58 GMT

This is something that has bothered me for a long time. A graph is a pictorial depiction of a set of data. A Garrison stress curve is a graph depicting a set of data. The question I have is "Where did that data come from?" It does not seem to me that a professional engineer would set out to design a fly rod by drawing a curve on a piece of graph paper that represents data. What am I missing? We use these curves in several rod analysis programs to twiddle and tweek...