I'm working on a Calstar BT6460XH.
The blank is short and stiff and my attempts to "find the spline" are getting inconsistent results. I've never been very confident on my ability to find the spine via the "bend it, roll it, and mark where it stops" method.

As I was sighting along the blank, I noticed that there's a distinct white line running the length of the inside.
I assume this is where the fiberglass roll was joined.
If so...is this the spline?

I can post a pic if someone can enlighten me as to how.

The spine is not a physical thing - it is an effect created by various manufacturing anomalies. And it really plays no role in rod performance. I suggest you read this: [www.rodbuilding.org]

The white line is most likely the initial tack of the prepeg pattern to the mandrel.

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Monday call then an ask , it would not hurt one bit , saying that Ton knows his job very well , so you can trust his comments on your question I think

William Sidney
AK

Thank you very much!

Is the "spline" always parallel to the blank or can it be a spiral around the blank?

No - then they would be called ribs.
Herb

Daniel,
If you can't find a noticeable spine on the rod - there likely isn't a noticeable spine on the blank.

If not building on the spine, just roll the blank on a flat surface to see if there are any slight bends in the rod. If not, rotate the blank however you wish to build your rod.

But, if you note that there is a slight bend somewhere on the blank, then the typical advice is to build on the straightest axis. Your choice as to whether to build with the bend pointing up, or the bend pointing down.

But, likely not a good idea to build with the bend pointing to the side because it is rather common for folks to sight down a rod. They will normally sight down the rod as if they were holding the rod in a conventional manner - i.e. with the guide on either the top or the bottom of the rod. If there is a slight bend in the rod blank, and one sights down the top or the bottom of the rod - the slight apparent is not apparent. But, if one sights down the rod and the bend is to the side, the slight bend may really pop out and bother the owner or user of the rod.


Best wishes

The spine effect does not run along the blank in a straight line or on a particular axis. It rotates around the blank. If you spine the entire blank, you are getting the overall effect on the total length. If you spine it from say, 1/3rd of the way back from the tip, it will be in a different place and will be the overall effect only on that portion of the blank. Again, the spine is not a physical thing.

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If the "spine" of a rod blank follows the twist of the graphite or fiberglass cloth threads that comprise the fabric which is a modern fish pole, which part of that twist should I use to locate my straight-line guide train? I prefer science to faith when building rods.

The very best thing to do with the word "spine" and fishing rods and fishing rod blanks is to simply forget about it and won't worry about it.

Build the rod so that when sighting down the rod blank on the side or off side of the guides - the blank is straight and then build the rod.

Best wishes.

Phil Ewanicki Wrote:
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> If the "spine" of a rod blank follows the twist of
> the graphite or fiberglass cloth threads that
> comprise the fabric which is a modern fish pole,
> which part of that twist should I use to locate my
> straight-line guide train? I prefer science to
> faith when building rods.

The spine effect of a rod blank does not follow "twist" of glass or carbon (most carbon blanks feature a linear lay-up). Rather it is simply the result of about 7 manufacturing anomalies. If those anomalies were not inherent in the way rod blanks are made, there would be no spine effect.


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Build on the straightest axis, up or down. Spine doesn't matter. If you really just have to, put the rod on solid ground, straight up and push down on the tip. Mark the inside bend, that is the spine.

Outside is the spine - it is the softest/weakest axis.

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