Questions about axe handles (fawns-foot to start with)

FortyTwoBlades said:
As I said, it increases the impulse of the blow, or the amount of energy transmitted over an interval. Moving the edge further ahead will cause the edge to impact the target sooner, extending the period in which the blow is actually occurring due to follow-through. The actual difference in period is incredibly small but makes a significant difference in the actual amount of energy transferred. Imagine, for instance, how poorly an axe would cut if the edge actually trailed behind the handle. Your swing corresponds with a prescribed section of an arc. The actual radius of that arc will vary greatly, and while the length of the handle is one factor, the compounded action of your pivoting joints will actually have a very large effect on the radius length, placing the epicenter well behind you under most circumstances.
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Good discussion. I would imagine that if the swing is correct and hits at the right angle, the force at impact will take it as far into the wood as it will based on mass, sharpness, wood density etc.
I agree that having the cutting edge as close to the moment arm as possible is best, but I would think that head shape (Maine wedge anyone?) would have greater effect on this than handle shape.
 
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FortyTwoBlades said:
As I said, it increases the impulse of the blow, or the amount of energy transmitted over an interval. Moving the edge further ahead will cause the edge to impact the target sooner, extending the period in which the blow is actually occurring due to follow-through. The actual difference in period is incredibly small but makes a significant difference in the actual amount of energy transferred. Imagine, for instance, how poorly an axe would cut if the edge actually trailed behind the handle. Your swing corresponds with a prescribed section of an arc. The actual radius of that arc will vary greatly, and while the length of the handle is one factor, the compounded action of your pivoting joints will actually have a very large effect on the radius length, placing the epicenter well behind you under most circumstances.
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Why don't sledge hammers have curved handles?;)
 
quinton said:
Why don't sledge hammers have curved handles?;)
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The first reason is two sided striking. However, every other implement that I can think of that is used for efficient energy transfer through striking is straight. I like the discussion, but regardless of the true answer to the efficiency question, I think that is incidental to it's design. My feeling is that the design started out as form over function, but I don't know the truth there. At the very least, it was not designed with purpose driven intent by an engineer.
 
The curve that's important in this case is the crank of the fawn's foot--those last few inches cant the whole axe forward, increasing the forward lay of the edge. A lot of really sexy curved handles out there are really just for looks (as far as I can tell) rather than having an effect on the swing itself. I've seen plenty of high-curve handles that deviate in one direction only to return to the same point long before reaching the hand. A single curve in the neck can have a large effect on balance, and something of an effect on effective edge positioning, but when you have that little curve at the end of the full length of the handle it moves the edge a few inches. I have a 36" Link handle here that's straight until the end where it cants 10°. That moves the edge an additional 6" forward along the arc. :)
 
Some people can efficiently use a curved haft, some feel more comfy with a straight one.. that is the difference.

As a carpenter I've seen newb's show up on the job with new tool belt, tape measure, and a big curved haft California framer. Generally after first payday they come back to work with a 20oz Estwing.
 
quinton said:
Why don't sledge hammers have curved handles?;)
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As jblyttle said, two-sided striking is one reason, balance is another, and accuracy of blow placement is a third. BUT have you seen railroad spike mauls? The reason for the long head is the same principle at work, but the head length is the means used to achieve the effect rather than a curved handle.

ry%3D400
 
42,
It sounds like you are assuming a constant force is applied to the handle during the swing in your analysis, meaning the integral of that force may be significant for the extent of the penetration. I may not swing correctly, but most of the force I apply at the beginning of the stroke. I can see pushing it in a racing situation, but generally it seems just to add stress to the impact and do little or nothing productive. Either way, I'm guessing the effect of the axe's mass and velocity at impact greatly overwhelms any small force applied to the handle during or after impact.

What am I not getting?
 
In cases where the head is merely loosed towards the target the curve creates a point of rotation that significantly tightens the radius of the curve, causing an acceleration of the head. Which is what would probably be happening in the sort of stroke you're describing.
 
FortyTwoBlades said:
As jblyttle said, two-sided striking is one reason, balance is another, and accuracy of blow placement is a third. BUT have you seen railroad spike mauls? The reason for the long head is the same principle at work, but the head length is the means used to achieve the effect rather than a curved handle.

ry%3D400
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Wikipedia

They have an elongated double faced hardened steel head. The head is typically over 12 inches (30 cm) long to allow the user to drive spikes on the opposite side of the rail without breaking the handle.
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idaho_crosscut said:
the fawns foot typically feels better on the wrists as you are chopping all day, because it doesn't over extend your top wrist as much-- but style probably played a strong factor as well. thin handles are lighter and IMO much easier to grip if they have a good wide swell at the foot. the thinner handle is preferable due it is ability to limit impact and shock into the head, and limit vibration down the handle.
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That pretty well sums it up.

Octagonal hafts help to register in your brain exactly how the the haft is oriented. Any slight twist of the haft is noticed and corrected for right away.

Dudley Cook's assertions in 'The Ax Book' about the inaccuracy of curved hafts is wrong or at least greatly overstated. If there was anything to that notion then racing axes would have straight hafts. They don't. 'Nuff said.

Length, weight and grind are all so much more important than handle style. I use straight and curved hafts interchangeably. As long as the haft isn't warped and has a decent swell I'll be OK with it.
 
FortyTwoBlades said:
As jblyttle said, two-sided striking is one reason, balance is another, and accuracy of blow placement is a third. BUT have you seen railroad spike mauls? The reason for the long head is the same principle at work, but the head length is the means used to achieve the effect rather than a curved handle.

ry%3D400
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No. The reason for the long head is to prevent overstrikes, i.e. hitting the rail with the haft when driving a railroad spike. See video at 4:45.

https://www.youtube.com/watch?v=3r_cI3kYYhM
 
The difference would be in working all day. If you are working for a few 30 second bursts, as a racing chopper, it is much easier to compensate for a handle that has less accuracy, and use the benefit of power (in wood that only takes a few hits anyway). Over hours of work the tradeoff is more likely skewed towards accuracy since it is harder to compensate when tired.

The racing competitiors are also highly trained, so they have become accurate with curved handles in spite of the shortcomings and not because the accuracy of straight handles is overstated. Comparisons to racing axes to prove what is correct is much like saying one should tune their cars based off of Formula 1. How long will your car last at 14,000 to 20,000 rpm?
 
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Square_peg said:
Octagonal hafts help to register in your brain exactly how the the haft is oriented. Any slight twist of the haft is noticed and corrected for right away.

Dudley Cook's assertions in 'The Ax Book' about the inaccuracy of curved hafts is wrong or at least greatly overstated.
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These two factors are strongly connected. Because the hand actually guiding the axe is commonly the one sliding down the length of the handle, it greatly diminishes the degree of influence of the hand holding the curve at the end, and the information of that hand helps guide the position of the other. While small misalignments are magnified in the final moments of the blow, a skilled user will have likely corrected this during the earlier stages of the swing and their wrist is unlikely to deviate when they loose the head.
 
42, my sympathies. This concept was obvious to people who couldn't even write, but you try to explain it to grown, educated folks and this is what you get.

Carving axes hung wide "open" when hung on curved handles, same idea, they are exploiting the concept. Downward curved knives, knives with curved handles which resemble almost identically an axe handle, used all over the planet by people who have no specific academic understanding of physics - same idea, as 42 said. Swing a straight axe (or knife) from point A to point B and then swing a curved axe - same head, same length - from the same points. The head on the curved handle impacts sooner when traveling the same distance. Just hold one of each on your hand out in front of yourself and you will witness this hearsay, convenient voodoo first hand. Whether you choose to ignore physics or not is irrelevant, how useful it is for the tool's intended purpose is relevant.
 
I like the "handshake" grip I get from a curved handle and the more relaxed wrist angle. While I can't claim to have swung an axe for more that a few hours at a time I do see tools in everyday use that still show some preference for the design. Anytime I see a crew framing a house, most, if not all the crew will have a framing hammer with a curved handle hanging off their belt. I think the more relaxed wrist angle is a big part of this. If you look at the evolution of pistol handles, fencing sword handles, even saw handles you'll see design shift from a straight handle to one that curves to allow a more natural wrist angle.
 
cityofthesouth said:
42, my sympathies. This concept was obvious to people who couldn't even write, but you try to explain it to grown, educated folks and this is what you get.

Carving axes hung wide "open" when hung on curved handles, same idea, they are exploiting the concept. Downward curved knives, knives with curved handles which resemble almost identically an axe handle, used all over the planet by people who have no specific academic understanding of physics - same idea, as 42 said. Swing a straight axe (or knife) from point A to point B and then swing a curved axe - same head, same length - from the same points. The head on the curved handle impacts sooner when traveling the same distance. Just hold one of each on your hand out in front of yourself and you will witness this hearsay, convenient voodoo first hand. Whether you choose to ignore physics or not is irrelevant, how useful it is for the tool's intended purpose is relevant.
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No one is trying to give him anything, I think that we all respect his knowledge and like the discussion. I am absolutely open to learning something. Also, I at least don't question that the head gets there sooner, what we are trying to grasp is why this would equal more force, deeper bite, more efficiency etc. I am not claiming to be correct, it is just that I don't yet understand why (or if) I am wrong.

This isn't to be argumentative, it is to get to the correct answer, whatever it may be, and have everyone gain better understanding. Debate is a healthy exercise, as those who were wrong gain new knowledge, a those who were correct, through thorough explanation, gain deeper understanding of what they already knew. :)
 
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