I generally go with the straightest axis on rods. Someone recently mentioned building on the spine of a high modulus blank with a very distinct spine as important.

What do you guys do on blanks like this? Mostly looking at bass-walleye type spinning rods.

Thanks - Marc

Keep it simple - that's all I can handle!

If you have a straight blank then build on the spine if you want, but I wouldn't build on a spine that is not straight.

I've only built on the spine so I guess you can say that's my preference, for reference I build on St. Croix SC3 and 5 blanks most of the time and they are usually very straight.

@John - when building on the straightest axis do you find that the rod twists under load? That has always been my concern and when building solid carbon ice rods it's amazing how much they twist if not on the spine.

Only with guides on Top of the blank A spinning rod or a spiral with guides at the 180 can not and will not let guides turn upward

Bill - willierods.com

Nate Nelson Wrote:
-------------------------------------------------------
> I've only built on the spine so I guess you can
> say that's my preference, for reference I build on
> St. Croix SC3 and 5 blanks most of the time and
> they are usually very straight.
>
> @John - when building on the straightest axis do
> you find that the rod twists under load? That has
> always been my concern and when building solid
> carbon ice rods it's amazing how much they twist
> if not on the spine.

Nate,

When line is strung through guides on a rod and the rod is loaded by applying tension to the line a lever arm effect is created through the guides as the line attempts to take the path of least resistance along the inside curve of the bent rod. If the guides are aligned along this axis they serve to stabilize the rod and overcome other forces (like a spine on a different axis) which might tend to twist a rod. The converse is also true - if the guides oppose this axis, the lever arm effect of the guides will twist the blank as the line attempts to take the shorter path (overcoming the effect of the spine attempting to keep the blank from twisting.) The lever arm effect of the guides, caused by the line taking the path of least resistance to the inside curve of the blank when the rod is loaded, trumps the much less significant effect of the spine every time.

That's not to say that you can't, or should not, build a rod to take advantage of the smaller effect of the spine if it compliments the lever arm effect of the guides. By all means do so if it is advantageous to how the rod is intended to be used.

There's a lot of history, lore, and misinformation about blank spines. Let's face it - it's a selling point, most big mfg can't take the time to find and keep track of the spine at the build scale they operate their businesses at. But we, as custom builders can. The trick is knowing when it's appropriate to do so.

I check the spine on every blank and on multi-piece rods I check each section. It only takes a few seconds. If i'm working with a multi piece rod, I'll align the individual spines. Then I rotate the rod sighting along the blank looking for straightness and for lack of a better term droop or sag. I try to learn about the individual blank's characteristics. Once informed, I take into account how the rod will be used and make a final decision as to the actual axis I will orient the build to.



Edited 2 time(s). Last edit at 06/16/2015 01:32PM by John E Powell.

Rod twist is determined by guide placement, not spine orientation.

Also, the strongest or greatest deadlift capacity of a rod blank is generally not found along axis where the spine effect is most noticeable.

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Not sure why the modulus of the blank would make any difference. [www.rodbuilding.org]

A shorter guide will lessen the amount of twisting torque as well. More than a few years ago I had the guides on a 5'6" bait casting spinnerbait rod replaced. The person put guides on it that were taller than the guides that came on it from the factory. With a fish on, the rod twisted so badly that at times it was a struggle to keep the rod oriented properly. Especially if I had a big fish on. It was so bad that I eventually just stopped using the rod.

I loved that rod, so last year I decided to replace the guides myself. The rod is now back to being the rod I loved so much before the initial guide replacement. I also ended up with more guides on it, which I am sure helped reduce twist by contolling the path of the line as it traversed the length of the rod.

A shorter guide will lessen the amount of twisting torque

But will not - eliminate it - It is still there

Bill - willierods.com

I mention higher modulus because higher mod - high performance blanks tend to be less forgiving.

Thanks - Marc

Keep it simple - that's all I can handle!

I always build on the spine. You will notice whatever modulus of blank, when you flex a rod blank against the spine and then with the spine there is a large difference in the flex of the blank. For multipliers the casting and power of the blank can be drastically effected. I do mainly beachcasting so the casting and retrieval of fish can be effected and totally effect your perception of the blank you are using. Finding the spine is the simplest thing to do, lots of articles on how to do it.

You give up some power and response when you orient the rod so that it flexes along the spine. Of course, it's impossible to fish a rod on only one axis so much of this is a mute point. But for the best sensitivity, power, deadlift capacity, etc., building on the straightest axis is the ticket.

There is no right nor wrong way to orient a blank. It's up to the builder to decide for himself and/or his customer.

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When I say build on the spine, when you find the spine for a multiplier you build on the concave side, for a fixed spool you build on the convex. By this I mean put your rings on the concave flex for a fixed spool; the rings go on the convex. This always gives you the best power for the rod in casting and playing the fish