Two spine questions:

1.) Generally, is the spine always straight or can it wrap around the length of a section of a blank?

2.) Are than any instances when you would want to orient the spine 180 degrees between the tip and butt section on a two piece blank?

What we call the rod spine is not a physical thing, it is an effect created by several manufacturing anomolies. For that reason, the position of the effect can orient itself differently depending on whether you are looking for the effect over the entire length of the rod, or just a portion.

For most builders, it is important to find the spine as it effects the entire length of the rod.

Please see more on rod spine on the FAQs page on this site.

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short answer is yes, it can spiral around.
if you try to spine a blank by flexing only a portion of it, it will come out totally different than by flexing the whole thing

as far as question #2, I can't think of a reason to do it that way, but honestly never tried it either.

When I'm building for big fish and building a big, heavy duty type rod, I want to build on the straightest axis and just forget about the spine. I put the upward bend or what I've heard called the natural bend of the blank so that the tip points up. When you sight down it, it will appear straight although there will be some slight upward bend. If you check this position for spine you'll usually see that the spine will be somewhere off to one side or the other. For some reason, usually to the left. Not exactly 90 degrees off, but somewhere between about 60 to 120.

The spine should be "very" reasonably straight. I know that I would not build on one that is not and I would never expect a customer to do so. This anomoly is created by several different parts of the manufacturing process, "but" is totally controllable by the engineering and assembly processes.

I would think that orienting the spine differently would only cause you problems with torque.

todd

It's been my experience that the straightest axis and the axis the spine lies in are almost never the same. If I orient the spine at the 0 or 180 degree postion, the rod blank will usually take off to one side or the other as you get near the tip. This is just my experience from building maybe 75 to 100 rods per year. It seems especially true on longer rods and almost always on fly rods.

Todd,

I tend to agree with Mike that the spine and the straightest axis is seldom the same on most of the blanks I build on. I must admit though, that the Lamiglas blanks I've used are the closest to being the same of all the blanks I've tried. Maybe its just been the luck of the draw, as I'm sure you know more about rod blanks than I. It seems most out of whack on the higher modulus type blanks to me.

Ray

Oh, I wasn't trying to state that the curve and the spine could be the same, more so that the spine could be made to be the same through the length of the blank....sorry for the confusion.

Todd

"When I'm building for big fish and building a big, heavy duty type rod, I want to build on the straightest axis and just forget about the spine. I put the upward bend or what I've heard called the natural bend of the blank so that the tip points up. "

Mike Ballard, re your post above, could you elaborate on the reason for ignoring the spine? I'd have thought thats when the spine would be important. Thanks.

If you're not casting then I really don't see where the spine has much to do with anything. I know this will fly in the face of some people's reasoning, but it just doesn't affect much else as far as I can tell.

We know it has nothing to do with rod twist or at least very little. Where you put your guides and how high they might be will determine if the blank either tries or actually does twist. Even before the articles in Rodmaker sort of exposed the old the 'spine on top to prevent rod twist' as a myth, I had figured that out on my own. It doesn't take a genius to see what really causes rod twist and its not where you locate the spine. Its whether the guides are on top or on bottom of the rod! If you put them on top the rod will try to twist regardless of where you put the spine so I opt for the straightest axis. I believe that has benefits of its own.

I want the most power I can get and the straightest axis to build on when building for large powerful fish and with guides that may be very high and need to be exactly in line with each other. I have been building this way for 15 years or better and not yet had a problem or complaint.