I just finished making a vertical spine finder. when I compared the marks to the of a regular spine finder on 3 seperate blanks
they were from 30 to 45 degrees off. What would create this?
Thank you.

The accuracy of the other spine finders or your own methods for spine finding.

One thing you may wish to remember is that the spine is an effect, not a physical thing, and the vertical finder will give you the effect as it occurs over the entire length of the blank. On most horizontal types, some amount of the blank is past the front bearing, so the effect is being shown only on that part past the front of the spine finder. That can easily give a result that is a few degrees different.

If yours were off as much as you say, then you have spine finders that aren't doing the job or you are using a bad method for finding it. I have both types here and the spine is usually shown to be on the same axis, and if not, it will only be off by maybe a couple of degrees between the various spine finders or by the hand rolling method.

Remember that there can be more than one soft axis and the vertical spine finder is the best tool for finding the softest, which is the effective spine. I'd almost bet you just didn't find the axis with the greatest effect when using your other spine finders.

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Question, Tom. With a verticle spine finder, by pressing against the tip and letting the blank roll to its effective spine, my impression is that what's being shown is really the spine of your tip section because that is what is prompting the blank to roll. When you place the rod on a ceramic tile and bend the blank's full length, the spine position will often shift from the tick mark found by the verticle method. I've been a little skeptical of this method for that reason, although many folks I trust say it's "the best." Especially with bigger rods, I want the full spine represented, not just the tip. Am I off base in this observation?

I'd say you are. You want to bend or press until you have a pretty good load on the rod so that you are getting the effect from not just the tip area. So it's not just the tip that is affecting the spine, it's the whole rod. However, let's remember that the portion of the rod that bends the most will contribute the greatest amount to the spine effect. The tip and mid sections generally fall in this catageory. The various tools we have for spine finding will never be any better than their operators.

In the next issue of RodMaker, we will have a bit more info than what has normally been presented on the spine effect. In the Q&A column I have laid out the 6 main causes (there are more, but these 6 are the usual culprits) that create the spine effect. Hopefully it will help builders gain a greater understanding of just what this effect is and what causes it.

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Tom,

I agree with Rob in thinking that placing pressure on the tip section does not reflect the same even pressures placed on the rod when fighting a fish. By putting pressure on the tip to force it to bend is almost the same as trying to break off the tip; where as the hand rolling and horizontal spine finders would allow the pressure to be distributed on the entire length of the blank (or the portion in front of the front bearing) yielding a more accurate representation of the overall spine. What do you think?

Ed,

If you will pressure the blank on the vertical spine finder, to the same point that you pressure it on a ceramic tile, or horizontal unit, or the hand rolling method, you will arrive at the exact same spine location.

On the vertical spine finder, you are pressuring the entire blank, not the tip, just as you are in any other method. The only difference is the blank is in a vertical position which negates the need for two bearings as found in horizontal spine finders. The method is the same.

By the very nature of their construction, vertical spine finders allow any introduced load or pressure to be applied to the entire blank and not just a section.

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I don't understand how anyone could only pressure the tip? Just bend or press on the tip and keep you other hand out of the fray and the entire blank will be pressured. I use a marble to simulate the bearing type vertical spine finder and get easy and good results with it. I get the same spine location whether I use my standard 2 bearing spine finder or my lazy man's vertical spine finder. I must be missing something on these posts.

I need to build me one of those vertical spine finders. Can anyone help explain what the easiest and best way to accompish that is? I understand how it works but it there parts such as the rolling point that rolls on the bearing surface available somewhere or is there machining involved? Any help is greatly appreciated.

Take a piece of 2x4. Drill a hole that will accept 1/2 marble. Insert marble and place rod blank on marble. Apply loading pressure on tip of blank.

This is an easy way.

Rolly's suggestion will work fine. There were also plans to build one in the July/August 2000 issue of RodMaker.

You can also use the wood base and fit it to accept a lathe live-center. They all pretty much do the same thing. The freer everything spins, the easier and more accuracte they tend to work.

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