Question for rod builders

[reggy]

With regard to the spine on a rod blank, does it matter whether the spine is on top(at 12 o`clock) or on the bottom (at 6 o`clock)?
I would not have thought it mattered, as long as it is not at any other position.

[Bazzawookooka]

Ok Reggie, I'll take the bait ...

Yes it matters, and it depends on whether the rod is for overhead use or not.

The basic proposition is this ... when the rod is loaded up it will 'spin' in your hand (or try to) if the spine is not set properly.

So, find the spine, the position the blank naturally rolls to when a decent curve is applied. For an overhead rod, the guides are placed on the OUTSIDE of the curve, and for a spinner rod (reel mounted below), the guides are mounted on the INSIDE of the curve.

I'm happy to be corrected if others believe this to be wrong.

Cheers, Steve

[reggy]

Thanks for clearing that up for me Steve.
Reggy

[Daintreeboy]

There are many schools of thought on this. For Carbon fibre blanks some advocate building on the straightest axis which is not always the spine. Others build on the spine as above and others build opposite the spine. That is the guides are 180 degrees to what was suggested above. The idea there is to build on the bend with the least amount of compression so its stronger. If it makes more sense explaining it, some people say building on the spine for say a spinning rod is allowing the rod to bend in its weakest point which is why it is bending so easily that way. So opposite that ensures the rod does not bend that way and is less stressed.
So there are three approaches right there!!

[galaxia1]

12 oclock is where you need your spine, either overhead or spin, find your spine with a slight bend in rod, the rod itself will find it for you. then you will get the best performance from your blank.
Regards galaxia1

[Stuart]

Well, all of the above are the usual answers. In fact if you read any article whether in print or on the web, they will all espouse to this same train of thought/opinion. Next thing you need to look at is the actual background of these people who are doing the educating on such matters. Have they rolled any blanks, have they designed any blanks; do they actually know the mechanics of a blank? Answer to most if not all, is none of the above. Have a read of the article I posted on this page.



When a blank is rolled, there is going to be overlaps of different flags, some have two or maybe three types of materials in the design. These overlaps play a big role in how distinct the spine will be. This slight overlaps also mean a slightly thicker portion of the blank. Let’s say the spine is located at 12 o clock when we load it up. Now put on your thinking caps. The blank wants to lock into a certain location as has already been established above. When a blank is loaded into a curve, it wants to twist into the curve of least resistance. So, if that’s the case, then the thickest part of the blank is now on top of the curve.

Stick with me guys. If the thickest part of the blank is on top, what’s beneath it? Well I’m glad you asked. It’s actually the thinnest part of the blank. So, we now have the thinnest part of the blank below the curve under enormous compression. You see, the top is in tension, and glass and or carbon are at their strongest while in tension. Did you know this little bit of trivia? When a blank snaps, it lets go below the curve, never on top. Do you get where I’m going with this? That being the case, you should at all times place the spine below the curve, that is to build below the curve where the blank wants to lock into. In fact, always build opposite to where the blank locks into. After 20 years, I have never felt a rod that wants to turn in my hand when built this way.

Sure many will say that’s BS because they have read somewhere its actually opposite to what I said. By all means do what you think is best by you. I can assure you though, after building over 16,000 rods and designed and rolled god only knows how many blanks, that what I say is sound.

Stu
Precision Rods

[Daintreeboy]

I agree with Stu. I've built stuff all rods and used to build on the spine until I read his article and now build opposite to it. Makes perfect sense.

[diabolical]

Curly question.............Why does a vertebrates spine run down its back and not along the chest? Mother nature, what would she know?

[Stuart]

Different cloths can have different transverse % ratios. You can buy cloth that has anywhere from 5% through to 95% of its fibre running transversely with the remainder running lengthwise.
Some blanks require a bit more transverse support depending on action and function. This means bugger all to 99.9% on this site. Its much like removing a tip from a rod. How many times have you heard, maybe done yourself, that once heated, you twist the top only to relies the blank tip has now De-laminted rendering it much like Kevin Rudd....useless. Again, most of these is meaningless to most, but just sharing.

Stufart

Precision Rods

[Mark Fisher]

You can also build opposite the "conventional" to achieve specific casting and fighting actions. eg spine located on the bottom side of a baitcaster allows the action to be stiffer (eg a 6kg blank will feel like the power of an 8kg) and the casting characteristics will be better as the blank will not be as stiff in the loading action in the back stoke of the casting action. Don't just get caught in believing "must be right theories" because there are exceptions to many things in rod building.