What makes for a really good chopper?

[sumtinfancy]

Hi,

As the title says, what is or are the main factors of or characteristics of a blade that make it good at chopping? I suppose the answer would depend on what exactly was being chopped, wouldn't it?

So the best for going through a log would be an Axe due to its particular qualities and the best for going through a tatami mat would be a Katana due to its attributes.So the question then is what is the most important factor, is it length,weight,sharpness of the edge,grind and shape of the blade or a combination of all those things that make a blade good at getting through material be it would or pool noodles or whatever?

I got thinking about this after watching a video of Ron Kosakowski (owner of TFW) chopping through a log with one of his swords, it was impressive how he used a relatively narrow blade which I assume does not weigh that much,to get through a decent sized piece of wood very quickly.As far as I'm aware the Filipino sword used was not traditionally designed for such a task but I must say it seemed to me that it did a better job than maybe other tools such as hatchets etc which are specifically designed for such jobs.

So that's why I got to thinking about what is the most important ingredient which goes into making a blade a great chopper, It seems like in the case of the Filipino sword, the very sharp edge is what helped it get through the log, but surely a sharp edge is not enough on its own, surely weight,shape, grind of a blade all play a role?

Anyway here's the video, see for yourselves.



[video=youtube;dy35FrlRMYA]http://www.youtube.com/watch?v=dy35FrlRMYA[/video]

 

[marcinek]

The correct geometry for the material being cut.

 

[Fancier]

I'll take a crack at this. Look to the tip heavy machete as the chopping optimized blade form, something along the lines of a bolo.
You want a blade that is sharp, long, thin, and wide, with significant flaring towards the tip. Sounds a bit like an axe, doesn't it?
The length gets you velocity and thus energy at impact. Thin and sharp transfers that energy into a deep bite that removes more wood.
The increased width towards the tip concentrates the mass behind the point of impact, giving additional momentum to drive the blade deeper into the wood.
Because you have a thin cross section and high impact forces you need a tough alloy. Production machetes are generally high carbon steel run pretty soft to give toughness. If cost is not a consideration you can get a custom made from a more impact resistant alloy and run the hardness up a bit to improve edge retention, but most of the custom choppers I see are FAR too thick for optimal wood chopping.
The barong style of machete is a very good general purpose blade shape, but it is not optimized for chopping wood.

 

[sumtinfancy]

I'll take a crack at this. Look to the tip heavy machete as the chopping optimized blade form, something along the lines of a bolo.
You want a blade that is sharp, long, thin, and wide, with significant flaring towards the tip. Sounds a bit like an axe, doesn't it?
The length gets you velocity and thus energy at impact. Thin and sharp transfers that energy into a deep bite that removes more wood.
The increased width towards the tip concentrates the mass behind the point of impact, giving additional momentum to drive the blade deeper into the wood.
Because you have a thin cross section and high impact forces you need a tough alloy. Production machetes are generally high carbon steel run pretty soft to give toughness. If cost is not a consideration you can get a custom made from a more impact resistant alloy and run the hardness up a bit to improve edge retention, but most of the custom choppers I see are FAR too thick for optimal wood chopping.
The barong style of machete is a very good general purpose blade shape, but it is not optimized for chopping wood.

Yes I pretty much agree, thanks for nicely defining the features of a good chopper, I assume you were joking when you said "Sounds a bit like an axe, doesn't it?" because that description of an ultimate chopping tool sounds the complete opposite of an axe to me. I was quite surprised by how the pinute performed on wood though considering it is a narrow blade and does not appear to be particularly tip heavy, maybe because its made of hard steel it can get away with having a very fine edge which bites deep but at the same time does not roll or get damaged which would be the case with a commercial carbon steel machete if it had such a thin edge. So am I right in saying that a convexed edge provides strength but reduces the biting ability?

 

[Huntsman Knife Co. LLC.]

Long, thin, forward heavy, appropriate edge geomety, and a comfortable handle.

 

[FortyTwoBlades]

I'll take a crack at this. Look to the tip heavy machete as the chopping optimized blade form, something along the lines of a bolo.
You want a blade that is sharp, long, thin, and wide, with significant flaring towards the tip. Sounds a bit like an axe, doesn't it?
The length gets you velocity and thus energy at impact. Thin and sharp transfers that energy into a deep bite that removes more wood.
The increased width towards the tip concentrates the mass behind the point of impact, giving additional momentum to drive the blade deeper into the wood.
Because you have a thin cross section and high impact forces you need a tough alloy. Production machetes are generally high carbon steel run pretty soft to give toughness. If cost is not a consideration you can get a custom made from a more impact resistant alloy and run the hardness up a bit to improve edge retention, but most of the custom choppers I see are FAR too thick for optimal wood chopping.
The barong style of machete is a very good general purpose blade shape, but it is not optimized for chopping wood.

Long, thin, forward heavy, appropriate edge geomety, and a comfortable handle.

^Pretty much these. I'll chime in a little later when I have the time to write out my thoughts on the subject.

 

[sumtinfancy]

^Pretty much these. I'll chime in a little later when I have the time to write out my thoughts on the subject.

Thanks 42, I look forward to reading your thoughts on the subject, if you could maybe name some commercially available tools that best fit the bill I'd appreciate it, preferably something light not too long and fast in the hand.Thanks

 

[FortyTwoBlades]

Ok--here goes. There are a TON of different aspects that contribute to making a good chopper. Amongst the greatest of those factors are, in no particular order:

Distal mass distribution
Sectional density
Sectional volume
Distance of sweet spot from point of pivot
Total mass
Rotational inertia
Angle of presentation
Blade width at point of impact and spatial relationship to grip centerline (affects the impulse of the blow)
Technique

As I can't presume what you are or aren't familiar with in terms of the above concepts just let me know if you want an in-depth explanation of any of them and why they're important--it should help cut down on the "wall of text syndrome" that technical posts like this can suffer from

Ultimately the "sounds a bit like an axe, doesn't it?" is actually a very accurate statement because an axe has almost all of the mass concentrated at the very end of a long handle and has very high sectional density (which is to say that most of the mass is concentrated vertically over the target rather than to the side), and the mass itself is fairly high. The winding technique used by some advanced axe users allows for increased acceleration time which overcomes the high rotational inertia of the tool, and the depth of the bit extends far past the centerline of the grip. The one thing that axes often suffer from compared to tools like machetes is that even the thinnest of eyed axes is fairly thick, but this is compensated for in a lot of different ways, including the increased ability of many axes to prevent binding during the cut which more flat geometries can suffer from due to increased surface contact with the cutting medium.

Just let me know which way you want to steer the conversation and we'll take it from there. I don't profess to be an expert or anything, but it's something I've done some research on, gotten plenty of dirt time with, and given TONS of thought to so I think I've at least got some insight to share.

For a commercial chopper that blasts wood very well, the Imacasa 20" Panga and Rozador machetes are favorites of mine, and of course my own Baryonyx Machete.

 

[TheSolitaryTraveller]

Depends on what you mean chopping if you meant whacking wood until you got pieces then that's all about directing the force of the impact onto a small point to maximize the depth of the strike.
But if you meant pounding a blade through wood thus batoning it, that's a matter of blade thickness, bevel, and also total surface contact (more is bad thus more friction and more energy needed).
Also weight is important in all matters of chopping since more weight means more energy in each hit, thus less energy wasted in needing more hits. Also note for batoning the more wedge shape that helps it split the wood, dampens it effect at piecing into the wood thus each hack is less effective since it disperses it energy faster.

 

[tatfiend]

I suspect that the axes used in timbersports are as close to the ideal as the sports rules and the type of wood being dealt with in competition allow. After all those competitors are competing for substantial money prizes so are going to get the most effective competition tools that the rules allow. Amazing to watch how fast they can chop through a substantial size log.

 

[FortyTwoBlades]

Depends on what you mean chopping if you meant whacking wood until you got pieces then that's all about directing the force of the impact onto a small point to maximize the depth of the strike.
But if you meant pounding a blade through wood thus batoning it, that's a matter of blade thickness, bevel, and also total surface contact (more is bad thus more friction and more energy needed).
Also weight is important in all matters of chopping since more weight means more energy in each hit, thus less energy wasted in needing more hits. Also note for batoning the more wedge shape that helps it split the wood, dampens it effect at piecing into the wood thus each hack is less effective since it disperses it energy faster.

Batoning would be splitting, which requires a very different set of parameters.

 

[sumtinfancy]

Ok--here goes. There are a TON of different aspects that contribute to making a good chopper. Amongst the greatest of those factors are, in no particular order:

Distal mass distribution
Sectional density
Sectional volume
Distance of sweet spot from point of pivot
Total mass
Rotational inertia
Angle of presentation
Blade width at point of impact and spatial relationship to grip centerline (affects the impulse of the blow)
Technique

As I can't presume what you are or aren't familiar with in terms of the above concepts just let me know if you want an in-depth explanation of any of them and why they're important--it should help cut down on the "wall of text syndrome" that technical posts like this can suffer from

Wow thanks for the details 42, I dunno if I'm gonna be able to digest everything you said but I think I get the gist of what your getting at, I think you missed out "velocity", surely the ability of the blade to be swung at speed is a factor, unless of course that has been covered by one of the technical points above and I've failed to recognise it

Just let me know which way you want to steer the conversation and we'll take it from there. I don't profess to be an expert or anything, but it's something I've done some research on, gotten plenty of dirt time with, and given TONS of thought to so I think I've at least got some insight to share.

I guess when it comes to chopping ability, it really does depend on what needs to be chopped.There probably isn't one tool that would excel at chopping various different things.I can see how a big heavy chopper like an axe would be good for big logs but not so good at thinner lighter more flimsy targets.An axe would need a solid immovable target to absorb the energy of the chop being delivered,whereas lighter freestanding targets with some give would need a faster sharper tool to slice through.I suppose that's why the machete is so popular as it tries to strike a balance and has the heavy chopping capabilities as well as the ability to deliver a fast slicing type chopping cut.

For a commercial chopper that blasts wood very well, the Imacasa 20" Panga and Rozador machetes are favorites of mine, and of course my own Baryonyx Machete.

I came across the oberst while I was checking out your Baryonyx which judging by the demo vids is a formidable logger, but I always appreciate the weapon capabilities of any bladed tool and the ability for a blade to be maneuverable I think is one of, if not the most important factor.Its why I was so impressed by the pinute in the vid I posted, that thing evidently makes for a great chopper but at the same time retains its agility and no doubt ability to deliver very fast devastating cuts.

 

[sumtinfancy]

I suspect that the axes used in timbersports are as close to the ideal as the sports rules and the type of wood being dealt with in competition allow. After all those competitors are competing for substantial money prizes so are going to get the most effective competition tools that the rules allow. Amazing to watch how fast they can chop through a substantial size log.

Yeah I checked out some of those guys and their tools, and yes I'm sure they're at the top of the food chain when it comes to chopping trees. I prefer watching the bladesports competitions though as the competitors have a variety of targets for cutting witch in turn presents a tougher challenge IMO and places a demand on the competitors and their blades not found in single target comps.

 

[FortyTwoBlades]

Wow thanks for the details 42, I dunno if I'm gonna be able to digest everything you said but I think I get the gist of what your getting at, I think you missed out "velocity", surely the ability of the blade to be swung at speed is a factor, unless of course that has been covered by one of the technical points above and I've failed to recognise it

Yup! Ability for the user to accelerate the tool falls under rotational inertia. You're not just fighting the direct total mass, but the leverage caused by the distribution of that mass. This also impacts the ability of the tool to deliver force to the target. Think of holding a sledge hammer upside down with the head acting like a pommel. You'll be able to swing it faster and easier than holding it in the normal direction, but try driving a peg with it that way and you'll quickly find why we use it the way we do! The mass hasn't changed, but its rotational inertia has. Chopping tools generally have to strike a balance between being heavy-hitters while still being controllable and nimble in the hand, all while trying to keep total mass down. After all, if you had just the sledge hammer HANDLE without the head you could swing it even faster than when holding the whole tool upside down, and deliver a greater amount of force to the target while weighing much less. It still would suck for driving pegs though.

I guess when it comes to chopping ability, it really does depend on what needs to be chopped.There probably isn't one tool that would excel at chopping various different things.I can see how a big heavy chopper like an axe would be good for big logs but not so good at thinner lighter more flimsy targets.An axe would need a solid immovable target to absorb the energy of the chop being delivered,whereas lighter freestanding targets with some give would need a faster sharper tool to slice through.I suppose that's why the machete is so popular as it tries to strike a balance and has the heavy chopping capabilities as well as the ability to deliver a fast slicing type chopping cut.

Yes--the slower choppers rely on having a stationary or at least fairly rigid target while lighter more flexible targets require higher velocity to cut them. You essentially want to sever them before they get the chance to be pushed out of the way instead. There are lots of ways to tackle this problem when balancing a design between functions.

I came across the oberst while I was checking out your Baryonyx which judging by the demo vids is a formidable logger, but I always appreciate the weapon capabilities of any bladed tool and the ability for a blade to be maneuverable I think is one of, if not the most important factor.Its why I was so impressed by the pinute in the vid I posted, that thing evidently makes for a great chopper but at the same time retains its agility and no doubt ability to deliver very fast devastating cuts.

The Oberst will likely be my next production undertaking after getting the Baryonyx rolling.

 

[Mitchell Knives]

Geometry, balance, mass, etc.

 

[Shotgun]

A good chopper has a good balance between biting deep and releasing the tool when you pull it out of the material being cut. The last I don't see anyone hardly ever talking about. I see countless vids and pics here and on youtube where someone chops a machete into a log and says how good the machete is because it bites really deep. Then they spend a great deal of energy pulling that wedged tool OUT of the log which IMO defeats the whole thing.

 

[chiral.grolim]

A good chopper has a good balance between biting deep and releasing the tool when you pull it out of the material being cut. The last I don't see anyone hardly ever talking about. I see countless vids and pics here and on youtube where someone chops a machete into a log and says how good the machete is because it bites really deep. Then they spend a great deal of energy pulling that wedged tool OUT of the log which IMO defeats the whole thing.

:thumbup::thumbup::thumbup:

I was just about to compose a message detailing the same thing! Penetration depth when chopping can be a severe hindrance to efficiency.

 

[FortyTwoBlades]

Proper technique for withdrawal is important under those circumstances, but yes that's important too!

 

[JayGoliath]

The correct geometry for the material being cut.

A very under-rated statement yet so TRUE. Some keep hacking perpendicularly onto the surface and wondered why it's not getting any deeper.
A correct method saves you energy and possibly injury as well.

 

[FortyTwoBlades]

A very under-rated statement yet so TRUE. Some keep hacking perpendicularly onto the surface and wondered why it's not getting any deeper.
A correct method saves you energy and possibly injury as well.

He said geometry, but yeah technique is important as well! I suppose that in terms of the question it comes down to the old debate of dishwasher vs. sanitizer if you know what I mean. YOU are the chopper, wielding a chopping tool--or the chopping tool is the chopper. Definitions definitions...