Cutting Poles

[NovaVault]

What are everyone's feelings/advise on cutting poles? My school is very cheap (only spend money on distance runners) and they've bought me one new pole in the last 3 years. I just recently got a 15' 170 carbon fx, the next thing I have to move up to is a old 15' 180 pacer carbon which is a bit much right now. But we do have a bunch on 16' poles that I'm thinking about cutting down to about 15'3. Anyone have any insight on this? and has anyone ever seen a skypole carbon before, we have one but it weighs a ton and looks a bit sketchy.

[Neo Vaulter]

Well if you cut a little off the top you're not really effecting how the pole works, just how high you can grip it.

Usually when people cut their poles its from the bottom. This basically moves the sail piece down the pole.

I'd would be sketched out on cutting any pole especially carbons as they are more brittle than regular poles.

You should contact Eddie Seese of vault world. He should give you an earfull. his email: prsport3@aol.com

[PVJunkie]

No manufac of poles would ever suggest cutting a pole. You change a lot about the pole when you do so. What are the 16 footers you have in comparison to the 15 footers? You may already have what you need without the hacksaw addiction.

Now as for the "brittle" thing. Carbon poles are as strong, and in most cases stronger, than non carbon poles. They return more energy than regular glass poles (have a higher tension when bent) and are lighter because carbon is stronger than fiberglass. Any carbon pole fresh out of the oven will match any all glass pole in max bend. The negative is a bang bruise or spike mark is more damaging to a carbon pole because there is less material in the overall pole. So if your not abusive to your poles a carbon pole will last just as long as any pole out there. Any pole with a bruise or spike mark, in the right spot, will fail. I play this game at the factory all the time for people. We take a scrap pole and bend the snot out of it. Then i grab the local hammer from the bench and whack the pole (carbon or regular) a couple of times and ask if they think it will break (i hit the pole pretty hard and leave obvious damage). They say it will break 99% of the time. So I then crank it up a notch and bend it even more than the first time, stop it in full bend and watch it. Then let it back out. Then I put one last little love tap in it (in the right spot) and it wont even make it to half way before it fails. Any damage anywhere on a pole is somthing to be wary of but it is far more likly to cause a failure in certain areas than others. Inspect all poles you use regularly and get rid of any that show obvious damage.

[vaultin chris]

u could just hold down on the pole. if the pole is 16 foot u can still hold around 15 feet on a lighter pole. plus why cut off a handhold u may need in the future.

[Neo Vaulter]

Now as for the "brittle" thing. . .

I stand enlightened. I always thought that the presence of carbon and it's lack of flexibilty as an element made the pole more brittle. Not the fact that there was less glass used.

But what about mandrel size? Are carbons that are made on smaller mandrels with thicker walls not as brittle as other carbons?

...and are lighter because carbon is stronger than fiberglass.

I thought the poles were lighter because carbon is in fact lighter then fiberglass, not because it's stronger.

[Decamouse]

Carbon - Modulus (Stiffness) - about 20 MSI, E-glass about 7 MSI, Ultra High Mod Carbon 41 MSI - big stiffness difference between carbon and std glass used in poles - Strength (Tensile - KSI) - Standard Carbon - about 340, E-glass about 150, the real trick is the type of carbon used, and where you put it - i.e. spiral wrap, body, sail etc. and how much - if you don't have testing or live experience you will get poles that are unjumpable, blow up, or perform poorly - The Carbon FX is light years ahead of the original Skypole Carbons (no-longer made) and better that the Pacer Carbon (which is a very good pole - probably better that all std glass poles for performance) - does that mean poles will not continue to improve - no - and it sure is fun to play

[PVJunkie]

I think..........once again those engineers.........what i meant to say is carbon is BOTH lighter AND stronger.

[Decamouse]

Neo (Matrix fan?) - regarding the mandrel and wall thickness - yes the smaller the mandrel (bigger the number) the more wraps or thicker the glass to get the same stiffness - Mechanics of Solids - Moment of Inertia = I = π(ro4-ri4)/4 --- I = pie(radius outside to fourth power - radius inside to fourth power)/4 - in plain terms the bigger the diameter the less wall thickness you need for the same Moment of Inertia - now - there is also a manufacturing and application side where if the wall is to thin it fails to easily due to the way you load a pole or how easily you damage it to the point it fails - so you could have the same flex pole on two different mandrel sizes - for std production there is a set mandrel to match length and weight combinations and material combinations (carbon vs regular) - we will not build certain wall thicknesses for safety reasons (thin side) - hope this helped

[vaulter580]

i have all pacer carbons in my bag, and all of them are cut, (from the bottom)
<---------------and just look at how much this one is bent!!

[Decamouse]

ok- explain why someone would cut a good pole - don't want to hear urban legend stuff - if the bottom was damaged , that is a diffent story - but just a little nugget to feed the thought process - cutting a foot off the bottom of a 17' pole will only change the relative sale piece and its center by just over 2% - do you real think you could tell the difference - and don't say it makes it a fastback because it isn't even close - now if you say it gives a placebo effect and you always jump better on cut poles - or that is what you had - ok - or you are used to a series like that - fine - but it will make transitioning from pole to pole more interesting unless you bought a whole series from the same source, same length and cut them all the same - by the way - changing you velocity at takeoff by .1m/s has a bigger impact on the force equation than the change in sail location you get by cutting the pole one foot - we know that higher force application does result in higher potential vaults - that is a fact - law of physics - shortening the length of the usable spring and it energy storage - not quite sure on that one -

[lonpvh]

Well, it does change the flex number a bit. Not always the same, but it does. If you do like us and check the flexs, the main reason for cutting them is to make sure that the spans in the flexs are really what we want. LB

[Decamouse]

Now that is a more reasonable answer - and yes cutting will not always change them the same amount - that is related to mandrel size, taper of the mandrel, angle of the trapezoid of the sail piece, body wraps - E and I are not constant throughout the length of a pole - try this flex a pole with the one fulcrum two feet down from the top - then flip the pole end for end using the same fulcrum placements - big difference - just another of those anal engineer things I guess