Bill -

I don't agree with either of those "tips". 1) Closed cars sitting in the sun do get hot, but not hot enough to soften epoxy resins. IF that were the case, you sure would have a pile of parts on the floorboards after a summer day in Lake Havasu, Arizona and; 2) There isn't any reason to stay away from high modulus blanks and the only legitimate factor that I see entering the decision making process is price.

Jim -

Ypur right That is why I added the Hmmmm

Bill - willierods.com

Bill & Jim
Those "tips" are One builder's view / opinion akin to building on the spine.... I put that link up there for anyone who wanted to see the steps involved in making a glass / graphite blank. The drill down at the bottom of the page "wanna learn more..." is a condensed summary of materials and is also pretty good - although a little "dated". As you read - please remember this was written by an foreigner - English not "first language".



Edited 1 time(s). Last edit at 09/19/2010 08:14PM by Ken Preston.

After seeing the discussions on this thread, I felt that I better ask Susan Loomis and Gary Loomis in person for their explanations for building on the spline...

-How Susan was taught (based on 35 years of rod building experience)

"If a blank were at all crooked you would want to place the guides on the spline to utilize the strength of the blank. Also, if there were more graphite wraps on one side than the other, you would use the spline to your advantage to balance out the weight."

Gary elaborated by saying "A blank with a small sweep would have the benefit of the guides straightening out the blank, based on the side that needed the guide weight to straighten it"

Susan's General Rule with building on the spline:

Fly and Spinning - on the belly

Casting - on the back bone


Another example she provided was when she recently built up a salt water blank for Marlin fishing. She mentioned that gigantic fish tend to cause the blank to twist, making sure to utilize a 90 degree angle to best fight the fish, you would want to build on the spline to reduce the torque and twisting that could cause the angle to change in a less than ideal way.

Peter,

Excuse me, but what Susan and Gary are describing isn't the spine. They seem to be talking about the straightest axis which is along the natural curvature of the blank (note the words belly, which is almost never on the spine).

.................

Jon emailed explained that Suzi was talking about what she calls the "visual spine." This is what we call the straightest axis or the natural curve of the rod blank. This is exactly what I suspected when I saw the reference to "belly." It's not what custom builders refer to when talking about the "spine." The spine is an effect created by the various manufacturing anomalies that occur when making a shaft.

..............

Peter,
There are half a dozen manufacturing variables that can contribute to where what we call the spine can be. You point out one of them which is how the layers of prepreg that are wrapped on the mandrel. In fact, any curve in the blank can also contribute to what we call spine as Tom's post suggests. However, the biggest factor is the fact that the cross section of blanks do not end up perfectly circular but are very slightly eliptical. Stiffness increases as the third power of diameter. If the diameter isdoubled, believe it or not, the result will be a nine times increase in stiffness. This means that a very small increase in the diameter of a blank in one plane will result in a significant increase in the stiffness in that plane as opposed to other planes.