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Thread: How a rods spine is Formed

  1. #1

    How a rods spine is Formed

    When it comes time to build a fishing rod people often ask what is a back bone and how do you locate it? Both these questions are very simple to answer. To begin with you need to understand how a blank is made and the processes it goes through before itís available as a blank. Most understand that blanks are made using several different layers of cloth to make up its mass and that these sheets are rolled around a mandrel to form its taper. Its all in how these sheets of cloth are laid that gives us one back bone or multiples. To begin with you need a mandrel, thatís a long piece of metal that the cloth will be wrapped around to form its shape and taper. The diameter of the mandrel, tip and butt will determine the rods action. Mandrelís can be made from alloy, mild steel, high speed steel it doesnít matter, as long as the mandrel is clean and straight as a die.

    To begin with we take a mandrel and apply a release agent over its entire length. This will enable us to remove the mandrel from the inside of the blank upon completion. Once the release agent is applied we take a roll of cloth from the freezer, cloth needs to be stored in a freezer because its pre impregnated with resin. We then use either meserments or templates to cut out the cloths shape which will also determine the rods action and power. If we were going to make 20 blanks then we would cut enough cloth to do the whole run in one go. We now have our cloth cut and ready to be wrapped on the mandrel. We take our hot TAC iron and we carefully press this onto and against our cloth and mandrel. This makes the cloth edge stick to the mandrel so we can roll it with out the cloth moving every were. Itís absolutely critical that the cloth be laid with the fibre running up the blank in a 0 degree orientation. If the fibre runs a bit of centre then it can and will weaken the rod by more than 40%.

    Now, this is where things become a bit more complicated. We take or cloth and mandrel over to the rolling table. This table has one huge hydraulic arm that moves up and down and from front to back. The table in which the mandrel and cloth lay on is called a plenum. This plenum can be an air bag style; it can be just a hard bed with some fine cloth on its surface. The idea of the plenum is to keep the mandrel hard on the flat surface while it is rolled back and forth by this large hydraulic arm that compacts the cloth into a tight roll around the mandrel, sort of like rolling your own cigarette. Now this is where we start forming our back bone in the blank. After rolling the first sheet of cloth, we now have a start and a finish point that donít match up. What this means is that the beginning of the cloth were we tacked it onto the mandrel using the TAC on iron is overlapped by the end of the same piece of cloth. The tail end of the cloth may only overlap by a ľ inch but it now means that there is more material in one section than the other. This over lap means an extra thickness in the overlap of around 0.15 which isnít much at all. When we lay another sheet of cloth on the same thing happens. With every layer of cloth that goes on you will end up with some degree of overlap, it canít be helped because the diameter is always changing.

    Once we have laid up our last flag we then take the rolled mandrel to the cellophane wrapping machine. This contraption is going to roll cello tape around the blank from tip to butt maybe twice under a pre determined load. The purpose of cello tape is to compact the fibre and force out any air bubbles and excess resin. Cello tape is also heat resistant and contracts in on its self some what like heat shrink. Why? Because we are about to hang this blank and mandrel up in an oven for around 3 hours at 120 C. The heat softens the resin in the cloth making it run and fill any voids. With the constricting nature of cello tape the resin and any air bubbles are soon displaced to make a solid walled blank. While the blank is being baked, you get a bit of movement in the wall of the blank, material is moving along with resin flowing and air escaping. This is were we start getting irregularities with in the blank wall. Again this all adds to what we call the spin and in some cases multiples. After three hours the blank is taken from the baking oven and then placed in a tank of water to cool the blank, mandrel and to aid in the removal of the cello tape. The blank is then placed in a hydraulic pulling ram to remove the mandrel. After the removal of the mandrel the blank is trimmed to suite, the tip and butt is cut to the pre determined length. Back bones or spins as some call it is in fact a defect of the manufacturing process, a perfect blank is one with out any distinct backbone. And this is exactly how a backbone is formed; hope all of you have learnt something.

    Stuart Mackenzie
    Precision Rods

  2. #2

    Re: How a rods spine is Formed

    Why thanks matey for explaining this.
    Is there a factory around that does tours to witness these procedures??
    I'd love to see how everything is done
    I intend on living far so good

  3. #3

    Re: How a rods spine is Formed


    Send an email to Snyder Glas. There is contact details on this site under Products.

    A couple of years ago I sent an email to Snyder Glas about the appropriateness of a couple of blanks I was considering building.
    They were very helpful and invited me to their factory where I could have a look at the blanks, as well as a couple of others suggested as appropriate.

    The bloke I spoke to was obviously pretty busy, but willing to answer the questions I had.

    They are located Brisbane SOR somewhere, can't remember the suburb.

    You won't know if you don't ask.
    Last edited by Grunter71; 07-08-2007 at 07:46 PM.

  4. #4

    Re: How a rods spine is Formed

    Got a bit of brain over load from that, but found it very informative, thanks Stu.

    Brings me to a question.

    In the case of multiple spines what choices are there.

    I've come across this a few times, in every case I've chosen the dominant spine.

    On the other hand there have been times when I've not been able to detect any difference in perhaps two spines. What do you think?



  5. #5

    Re: How a rods spine is Formed

    Stuart if i was trying to find a back bone on a blank that had a dual helix construction how would go about it ?

  6. #6

    Re: How a rods spine is Formed


    Multiple spines are a fact of life in many blanks. You can choose the the most dominant which will work just fine. If you have two spines that are the same then pick one of them to build on.


    My own blanks have a dual helix which makes no diffrence to a spine. To locate the spine, hold the tip with your thumb and index finger and with the other hand support the blank around half way down. Flick the blank from from side to side so you can feel the blank click into postion.


  7. #7

    Re: How a rods spine is Formed

    Stuart, what do you think of this method? Place the blank upright, butt end down on a flat floor. then gently press straight down on the tip. As you say the blank will rotate a bit then "snap" into a preferred bend. I've done this a few times, and once the spot is marked it is consistent every time you repeat the process/bend the blank.

  8. #8

    Re: How a rods spine is Formed

    either way will locate the "backbone" I use the thumb and finger system, but have used your method as well, ends up the same.

  9. #9

    Re: How a rods spine is Formed

    Thanks for that Stu very informative even though I wouldn't know the first thing about the building process of rods.......yet.

    Finga if you have any success can you please give me a PM i'd love to do the same.

    Cheers Chris
    Democracy: Simply a system that allows the 51% to steal from the other 49%.

  10. #10

    Re: How a rods spine is Formed

    i have found some spines can spiral a bit up the blank. always used the butt on a smooth surface on the floor system, then i never backboned the tip, i always did it lower down the rod where the main load will be, not much use having a nicely backboned tip if it still wants to twist when loaded.
    not all do it, like others have found some with no, or almost no backbone.

  11. #11

    Re: How a rods spine is Formed

    That is the correct way to do it mate. However in saying that, it realy only matters on stiffer rods like that of heavy spin, game rods and chair rods that will be under more load than that of a small bait caster or whiting rod.


  12. #12

    Re: How a rods spine is Formed

    So the backbone is not something that is physically locateable, and is identified by the curve tendencies of the rod? Is it the back of the natural curve or the inside of the natural curve?

    I have an ugly stick overhead that always twisted. Put me off using overheads. I wonder if it was not built properly with the guides on the backbone/outside curve.

  13. #13

    Re: How a rods spine is Formed

    Very imformative post, easy to read explanations.
    Would love to see blanks being made, so will look into it next time i come north.
    Cheers Garryh.

    in Port Philip Bay.

  14. #14

    Re: How a rods spine is Formed

    The backbone is able to be physically located and all casting rods should be built on our as close as possible to the rods strength line.As you say the rotational torque that is potentially created by one not built correctly can be devastating when fighting fish on a rod not built correctly. We pride ourselves on the fact that we will not sell a casting rod that does not meet our guyide lines on backbone,many others in the same price category/assumed quality appear not too.GREAT FISHING Ian

  15. #15

    Re: How a rods spine is Formed

    There's a good vid on you tube about this. Worth a look.

    Avast ye matey!

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