Point Weight and Spine Change

albatross

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Is it possible to make an Easton ACE arrow weaker by 2 spines (620 > 720) by increasing the point weight.
 

BillM

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I asked a very experienced archer this type of question and he replied that it will have a detrimental effect on the arrow. Easton recommend a particular point weigh for their arrows and there is a slight leeway in using a heavier point. The point weight needed to make a 620 act like a 720 will likely exceed the leeway and will eventually cause the arrow to destroy as it will cause more bending upon release (archers paradox), the point needing a lot more energy to get it moving. It is probable that the carbon will delaminate from the alloy and the shaft will fail with possible severe consequences. This was the explanation I was given.

BillM
 

albatross

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@BillM. @gtek.

Thanks for the replies. It was as I suspected but I never realized the damage that could be done as the explanation from BillM points out very clearly.
 

geoffretired

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Perhaps the extra point weight makes the arrow bend more, but the weight slows down the string making the timing of the bends more like a stiffer spine.
You end up a bit like when you started.
 

Timid Toad

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Ironman
Increasing or decreasing point weight can give some very unpredictable results with regards to spine.
For Flight archery, it's very common to chop points down so you have only 10-20 grains of point. But that leaves very little shank, so almost the whole length of the shaft flexes, when normally the front 2-3" would be supported by the insert. So don't expect the spine to change as much as calculations might suggest.
In Clout, it's common to tinker with arrows to increase FOC enormously, by putting a rod into the shaft before the point goes in. This will weaken the arrow, but as a larger portion of the shaft is supported by the insert, it flexes differently.
It is possible to make a very consistent set of arrows with both these methods, but they work for a very specific purpose and both spine and behaviour as it leaves the bow cannot fit any spine charts.
Best advice: get the right arrows and flog the stiff ones.
 

Andy!

Active member
longbow.jpg

In order to hit the target, the arrow points away from it.
What you SEE is the paradox.

That's it.
Nothing else.
 

BillM

Member
This is what I knew as the definition of archer's paradox. It is the bending of the arrow shaft that allows the arrow to travel to the target otherwise it would follow the path the point was aiming. That is why excessive bending of the composite shaft will cause delamination and possible failure upon release.

Archer's Paradox

The term archer's paradox refers to the phenomenon of an arrow traveling in the direction it is pointed at full draw, when it seems that the arrow would have to pass through the starting position it was in before being drawn, where it was pointed to the side of the target. The bending of the arrow when released is the explanation for why the paradox occurs and should not be confused with the paradox itself. Flexing of the arrow when shot from a modern 'centre shot' bow is still present and is caused by a variety of factors, mainly the way the string is deflected from the fingers as the arrow is released.

Archer's paradox - Wikipedia

BillM
 

Aleatorian

Member
This is what I knew as the definition of archer's paradox. It is the bending of the arrow shaft that allows the arrow to travel to the target otherwise it would follow the path the point was aiming. That is why excessive bending of the composite shaft will cause delamination and possible failure upon release.

Archer's Paradox

Paradox: The term archer's paradox refers to the phenomenon of an arrow traveling in the direction it is pointed at full draw, when it seems that the arrow would have to pass through the starting position it was in before being drawn, where it was pointed to the side of the target.
As seen in Andy!'s picture

Explaination: The bending of the arrow when released is the explanation for why the paradox occurs and should not be confused with the paradox itself. Flexing of the arrow when shot from a modern 'centre shot' bow is still present and is caused by a variety of factors, mainly the way the string is deflected from the fingers as the arrow is released.
Flex round the stave of the bow causes it to hit right of where is is pointed, recurves/AFB only offset marginally due to finger deflection
Archer's paradox - Wikipedia

BillM
See bold text
 

Timid Toad

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And in this instance you have found one of the many ideas in which Wikipedia is incorrect. It should state modern *compound* bows. As all other bows are set up with the arrow outside of centre, and to allow for a fingers release. And paradox. Andy you have shown only the first symptom of paradox - the arrow pointing away from the target - the bending arrow does permit clearance of the riser and a return to the path towards the target.
 

Andy!

Active member
There is no symptom of paradox.
There's only what you see which looks to be incorrect, but isn't.

There is the explanation of the paradox. The explanation is not the paradox.

Would you like to get into an evidence war where I present all published references?
I have everything from an actual physical copy of the 1912 Field and Stream where Rendtroff coins it as toxophilist's paradox, the book with Elmer's reference to it, Stills from Hickman's high speed video of the phenomenon, through to the point where Kooi first calls the explanation of why, the actual paradox. For almost 100 years, people knew what archers paradox is.
Then came Kooi.
If you ever wanted to nail down a part in history where someone investigating a phenomenon totally hashed it a nomenclature level, it's right here:
You don't even have to consider yourself intelligent to work it out.

At figure one, he illustrates "archers paradox" which is the explanation for the paradox.
http://www.bio.vu.nl/thb/users/kooi/kosp97.pdf

If you trace the history, it's not even something you can argue about. It's just flat out what happened. You may as well argue that Hitler didn't invade Poland.
 

BillM

Member
OOps! I now wish I hadn't mentioned the word 'PARADOX'. Ask 100 archers at random what they think it means and the vast majority will associate the bending bit without the offset bit. Going back to the original question, all arrows bend upon loose of the string but adding excess point weight will cause the arrow shaft to bend more than the design intended leading to damage of the shaft. That was the explanation I was given by an experienced international archer and was what I wanted to pass on to the OP. This was in connection to composite arrows. The centreshot offset on my recurve is not really obvious whereas the offset on my longbow and horsebow is. Only by using the correct stiffness of shaft with a realistic point weight I achieve the desired dynamic result of the arrow attacking the target face. The arrows for my horsebow falls into the 'pound for pound' adage while the arrows for my longbow are about 10# lower. Stiffer or whippier arrows outwith this will go left or right depending on other factors meaning that I need to aim off. That's life I suppose.

BillM
 

BillM

Member
Yet another duplicate, but too much already said about 'archer's paradox' in a topic about making a shaft weaker by adding more to the point.

BillM
 

albatross

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Supporter
OOps! I now wish I hadn't mentioned the word 'PARADOX'. Ask 100 archers at random what they think it means and the vast majority will associate the bending bit without the offset bit. Going back to the original question, all arrows bend upon loose of the string but adding excess point weight will cause the arrow shaft to bend more than the design intended leading to damage of the shaft. That was the explanation I was given by an experienced international archer and was what I wanted to pass on to the OP. This was in connection to composite arrows. The centreshot offset on my recurve is not really obvious whereas the offset on my longbow and horsebow is. Only by using the correct stiffness of shaft with a realistic point weight I achieve the desired dynamic result of the arrow attacking the target face. The arrows for my horsebow falls into the 'pound for pound' adage while the arrows for my longbow are about 10# lower. Stiffer or whippier arrows outwith this will go left or right depending on other factors meaning that I need to aim off. That's life I suppose.
BillM
As the original poster of the question I was greatfull for this explanation.
 

geoffretired

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I think it's easy enough to get "archer's paradox" confused with arrows bending. After all, most people new to archery, think the arrows fly straight ( without bending) until they are told otherwise. They then associate bending with paradox because bending seems paradoxical and the message gets passed on.
 

Rik

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As the original poster of the question I was greatfull for this explanation.
I don't think it's been established to be accurate, though. I find it kind of boggling that anyone could assert that a shootable point weight would damage a shaft... I'd want to see evidence for that, as it's such a strange thing to say.
 

geoffretired

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I don't think it's been established to be accurate, though. I find it kind of boggling that anyone could assert that a shootable point weight would damage a shaft... I'd want to see evidence for that, as it's such a strange thing to say.
I think it is interesting to just imagine what point weight would be required to bring about the " spine change" in question. Would any readily available point that fits actually do the job?
 
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