The Ergonomics of Chopping (VERY LONG)

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Mike P. Swaim

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Sep 14, 1997, 3:00:00 AM9/14/97
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This post has a little to do with physics, a little to do with
descending arcs, momentum, and a good bit of admitted speculation
based on what I've seen so far. It's one guy's struggle to understand
why two similar tools sometimes perform radically differently when the
steel meets the wood. Mostly, this long post just seeks to address a
simple question:

"Can one determine how well a particular knife, machete, hatchet, ax,
kukri or other tool will chop wood simply by looking at it?"

I think that the answer is not only a highly cautious yes, but I think
that one can go a long way towards determining the outcome merely by
laying a straightedge against a picture in a magazine or catalog. That
certainly won't tell the whole story, by any means, but it might go a
longer ways towards figuring out the truth, than relying on the ad
copy hype.

By now some of you are probably wondering if I'm posting drunk, (again
;-), while others are probably wondering why it took me so long to
figure out something this obvious. ;-) Could've saved myself a whole
lot of time and $$ if I'd applied a turn of the century technique for
mounting or "hanging" an ax head on a handle to choosing big chopping
knives & machetes. The real irony is that it took a post on maces,
turned into a discussion on the physics of numchucks to get me to
really see what's happening when one swings a kukri. Follow that? ;-)

Let me take you on the somewhat torturous, winding path of one guy's
re-discovery of the simple and the obvious.

What's the most important factor in determining how well a knife,
kukri, hatchet, machete or other tool will chop hardwood?

A. Balance Point
B. Length
C. Weight
D. the handle

Before I tell you what _I_ think the answer is, let's look at what's
really going on in a one-handed downward chop. Other chopping/hacking
strokes are really just variations on a theme, so to keep it simple,
let's just look at a stroke like a simple hammer swing.

Depending on the person and the implement, the tool gets swung up past
vertical with either the wrist, or the elbow, or both acting as
pivot(s) & the edge of the tool describing an arc as it gets swung
back down into the target.

Now that's where I think that a lot of folks, (like me ;-), start to
get confused. They apply, or perhaps in my case, mis-apply a little
bit of knowledge of elementary physics to the tool and the descending
arc, and stop looking at the whole picture right there. In one sort of
cruel joke of a book that claims to be, "Everybody's Knife Bible", the
author, Don Paul, lays out a seemingly perfectly reasonable sounding
theory that since Inertia equals mass times velocity, then one can
double the effectiveness of one's chopper by merely doubling the
weight of the blade. I'll not even bother to get into his totally
preposterous suggestion that one should weaken the blade by drilling
holes into it to put on fishing weights to accomplish this blade
weighting. His theory of a heavier blade being able to cut deeper &
faster is fine in the abstract sense, but it doesn't really go far
enough to explain real variances in different shape blades. It doesn't
explain why, so often, I've seen an 18" 1lb. 6.5oz. US GI machete
outcut a 2 or 2.5lb. hatchet. (BTW-- I've seen that so often, now, on
logs up to 10", that I don't consider it a fluke.) If weight was the
most important criterion, then you ought to be able to cut down a tree
with a Maglight, or maybe an anvil. ;-) If all else is exactly equal,
then an increase in weight should result in better chopping, (to a
point), but all else is rarely equal. (Also, if you double the weight
of the average production knife, without otherwise changing it's
dimensions, you'll very likely snap the blade.)

If it's not mere weight, then how 'bout weight distribution? So why
can't you cut down a tree with a 5lb. pick? (You probably can, but
it'd take awile.)

OK, so surely it's got to be the overall length of the machete causing
it to describe a larger arc, causing more speed and more momentum and
inertia. Right? Uh-uh. Why does a shorter 12" blade machete outcut a
longer 18.5 CS Rifleman's Hawk hatchet? (It does,.... trust me. ;-)

If one took the weight, weight distribution & length arguments as far
as some writers seem to want to take them, one might almost get the
notion that a rockhammer would be a better chopper than a machete. ;-)

In an earlier post, I mentioned, perhaps too casually, that I didn't
see much difference in chopping ability between cheap hatchets &
expensive ones. Well, that's not exactly right. All hatchets are most
definitely not created equal. I do very much notice a difference, but
the differences don't fall neatly and evenly into price lines. I've
got one expensive CS Rifleman's Hawk, and one cheap generic Rigger's
hatchet that just don't chop wood at all well. I've also got one
mid-priced Estwing camp hatchet, and one cheap generic camp hatchet
that both do pretty well. So what's the difference between them? The
head sizes are all close enough that there shouldn't be much variation
in weight. The generic Rigger's hatchet has the most blade area, and
the Estwing has the least, yet the performance between them is
reversed from what you might infer from that. If anything, the longer
handle on the CS Hawk ought to make it the hands down winner, but the
reality is that it's just about the worst of the lot. Why?

Let me drop a bomb on ya. :-0 --Both of the lousy choppers have
straight handles & both of the good choppers have curved handles. Now
why, I wonder, would that make so much difference? Well, if you look
down at the log, the difference becomes painfully obvious. The ones
with curved handles are making _much_ bigger cuts. More of the blade
surface is coming into contact with the wood. Same thing is true of
the US GI machetes. They're making 5-6" cuts with nearly every swing,
whereas the best of the hatchets, (the Estwing), is only making 3"
cuts. This despite the fact that the machetes have straight handles.

So what's going on, and when the heck am I going to get to the point?
;-)

Let's take a look at an example that I think is most telling. When I
look at the wear patterns on my CS LTC Kukri & compare them to my US
GI machete, they are quite different. The LTC Kukri, shows the most
wear on about 4" of the belly of the blade. The US GI machete, shows
wear on over 8" of blade. Clearly the machete is contacting more wood
& therefore should be, (and is), more effective.

OK, so what about the argument that the hatchet concentrates more of
it's momentum into a smaller surface area & therefore should cut
deeper? Frankly, after trying both hatchets and machetes on many, many
different kinds of both hard and soft wood, I'm just not seeing that.
At least not with one-handed use. If anything, I'm seeing the thinner,
sharper blade of the machetes cutting deeper. This seems to hold true
for both cutting across and with the grain. Even in making kindling,
the sharper, thinner machetes seem to have the edge, (so to speak;-).
They're also much easier to pound through with a pounding stick when
they get stuck, than are the hatchets, due to the machete having so
much blade hanging out of both sides of the work.

In fact, for the first couple of cuts, one of the deepest cutters
that I've got is a sugar cane machete made of simple sheet metal. I
mention the 1st couple of cuts, only, because after that the edge is
so destroyed by the hardwood that it has to be re-ground.
None-the-less, it is illustrative of the point that the steeper
beveled hatchets just can't get as deep, as fast. They may, however,
be able to make mediocre cuts in hardwood for a longer time inbetween
sharpenings, but even that is relative to the hardness of the steel
used in the heads. (The Estwings are proving to be maddeningly soft.)

One can, of course, take either the concentration of force argument,
or the blade contact area argument too far. I don't think I'd want to
cut down any trees with either a pickaxe or a roll of aluminum foil.
;-) Now, since that example is clearly absurd, then let me hasten back
to where I see the real line being drawn. It's the difference between
one-hand use & two-arm/whole body swing use. Notice that throughout
this, I've referred to hatchets, not axes? Despite the best efforts of
Estwing to confuse the issue by calling their hatchets, "axes", there
is a difference. I see the difference as the vast increase in power
one gets when one switches from simple one-hand wrist/elbow motions,
to whole back/trunk/body motions using both arms and shoulders. At
that level, you've almost got to go to an ax, not just to concentrate
the blow into the wood, but to focus and minimize the shock
transmitted to the tool. (Remember the thread where a couple of
swordmakers pretty much said that woodcutting was considered abuse of
their tools? Given the enormous forces generated by a baseball bat
type swing, they've got some pretty good reasons to be cautious in
that regard. ;-) It's also at that point, that I think one can take
best advantage of the wider bevel and cheeks of an ax or splitting
maul.

It's probably worth pointing out that I've already managed to loosen
and loose a couple of the rivets holding on the med-soft plastic
Blackie Collins "D" handle on my small machete. This despite only
limited one hand usage. I think it's due to the plastic having more
"give" than the mil-spec hard plastic on the US GI ones.
None-the-less, it's interesting to contemplate how much force it takes
in shear vibrations to loosen up a couple of hammered in place locking
rivets. Likewise, I've managed to snap the molded plastic handle
completely off a 1/2 tang stainless bowie pattern just by chopping one
handed. What would two arms, two shoulders, a back and leg muscles do
to a chopping tool? I'll tell you from personal experience, that if
you want to turn a high quality 5' handled large brush hook into junk
in a hurry, try cutting down a 2' oak tree with one. ;-) At some
point, you may simply have to start really focusing the impact area,
not just for cutting efficiency, but also to save the tool.

Anyway, just on the off chance that anyone is still reading, I'll now
get to the main point. That is, that I think it's probably possible to
predict how well a tool will cut wood one-handed by simply drawing a
line from the area that would be where the little finger would most
comfortably and naturally wind up on the edge side of the grip,
forward past the edge. To illustrate what I'm getting at, take
whatever large choppers you've got laying around, and lay them edge
down on a flat hard surface, with just the pommel and the edge
touching the surface. What portion, and how _much_ of the blade comes
into contact with the table, yardstick or whatever?

Due to guards, oversized pommels etc. this may or may not show what
I'm trying to get at, but if you take a piece of string & draw it taut
between where your little finger most naturally grips the handle &
some pt. past the tip of the blade & then rock the knife or hatchet
down to the string until the blade just touches the string, then you
should see the area that is the natural "sweet spot" of the blade.
It's almost easier to see it the first time, by simply taking a ruler
to the edge side of a picture of a blade profile in a catalog. What
you're looking for, is the point at which the blade will first swing
through the target medium. Ignore false contact points like guards,
etc.

If not much, or none of the blade contacts the straight edge before
the last part of the usable grip area does, then chances are it won't
chop wood worth a darn. Also, if only the 1st 1/2 of the blade coming
out of the handle touches the flat, (or string), it won't do too well
either. A radically upswept skinning knife or scimitar are examples of
knife styles that won't be good wood choppers. Sound obvious? ;-> It
is, but it gets fun when you start looking at how little contact area
things that are sold as choppers really have.

In the case of the CS Rifleman's Hawk Hatchet & the Rigger's hatchet,
only the 1st inch of the less forceful bottom of the blade touch the
flat surface. What makes that particularly obnoxious, is that at one
time, at least as early as the turn of the century, it was evidently
pretty common knowledge among American woodsmen that for an ax or
hatchet to be effective, they had to be "hung" on the handle in such a
way that the 1st contact point is not more than 1/2-2/3 way down the
blade. In older texts, "centerline hung" was considered pretty good
for all around use. The curved handle, rounded blade small Estwing
touches the yardstick very near the center of the blade.
Interestingly, their longest and most expensive two handed model does
not, but I think that's because it's primary role was conceived as a
kindling splitter. (Perhaps more on straight handled hammers and
splitting mauls in a followup post, but not now. ;-)

In the case of the Ontario SP8 Survival Machete, it could be made into
a most interesting device, if only Ontario had bent the handle up
about 15-20 degrees. (Just a guess, that may not be the exact angle.)
As it is, it's actually less effective than some machetes that weigh
less, and I'm convinced that it's because it gets less blade on target
per stroke than the other Ontario US GI ones. (Sorry, Marvin, but I
believe it's the truth. Do you see what I'm getting at?)

Anyway, none of this does anything to describe other necessary blade
attributes, but quite often materials & grinds get all the attention.
Rarely, have I ever seen much in print about contact points and "sweet
spots". This is just my attempt to help correct that.

Thankyou for indulging me to the point of reading this far ;->

MPS--- remove asterisk in email address to email me


Matthew Rapaport

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Sep 14, 1997, 3:00:00 AM9/14/97
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In article <5vhtir$s...@camel3.mindspring.com>,

Mike P. Swaim <mi*a...@cphl.mindspring.com> wrote:
>
>"Can one determine how well a particular knife, machete, hatchet, ax,
>kukri or other tool will chop wood simply by looking at it?"

It seems to me that there are three general factors involved in this.

1) The over-all momentum of the blade at the point of contact
2) The length of the "sweet spot", and its relationship to the
fulcrum of the swing.
3) The edge geometry of the blade

Your analysis mentions (1) in an effort to show that it is not all-
important, and at the end mentions (3), but otherwise concentrates
on the effect of (2). I think this element is quite important and
as you say probably neglected by the media. It would be interesting
to see all three elements factored into a performance analysis of
real chopping tools (and knives). Thanks for the effort to this
point..

--
matthew rapaport The difference between theory and practice KD6KVH
is that in theory there is no difference,
m...@crl.com but in practice, there is. qu...@dfw.net

Marvin Edgeworth

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Sep 14, 1997, 3:00:00 AM9/14/97
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Dear Mr. Swaim,
Yes, I see what you're getting at. I believe you recommend the Ontario
ON-18 machete, $15.95 at the KnifeCenter (please correct me if I'm wrong).
If that's correct, I'll get one and try it out in a test with the SP-8.
Test may not be immediate - wife scrogged her knee, so I've been staying
close to home the last little while. )

Mike P. Swaim

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Sep 15, 1997, 3:00:00 AM9/15/97
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m...@crl.crl.com (Matthew Rapaport) wrote:

>Your analysis mentions ....
<snip>


> Thanks for the effort to this
>point..

So does this mean that we're going to see this respun into a magazine
article?

MPS--


Don Robinson

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Sep 15, 1997, 3:00:00 AM9/15/97
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Mike, I read every bit and enjoyed it much.
Logical argument and I agree. I'll take into consideration on my camp
knives..
Thanks,
Don Robinson
http://home.att.net/~don.robinson.cutting.edge/robinson.htm


Mike P. Swaim <mi*a...@cphl.mindspring.com> wrote in article
<5vhtir$s...@camel3.mindspring.com>...

Mike H.

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Sep 15, 1997, 3:00:00 AM9/15/97
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Interesting and entertaining article Mike S. You just made my
morning...

While working recently on design ideas for my (not everyone's) ideal
chopping camp knive, I've had similar observations regarding blade and
handle angle . Note that these are just my observations which in
reality could prove to be completely bogus. However, I do agree that
there is something here worth studying. For the sake of sticking to
the subject, I won't go into things like blade length, depth, width,
grind, steel, etc.

The very unscientific approach I used was to make a cardboard mock ups
of some different blade and handle shapes. By making the handle and
blades seperate units, I was able to play with angles. Handle angle
didn't occur to me at first. It was not until I got on one knee or
stood bend over and went through chopping motions in various positions
that I noticed womething felt wrong.

To see what I'm talking about try this simple simulation. Get a 12 to
24 inch ruler or straight edge. Hold it as you would a big knife.
Place a log or some prop down on the ground. Now get down on one
knee or stand as you would otherwise to chop that low. Slowly bring
the ruler down in a chopping motion until you would contact the
'wood'. Look at the 'blade' angle, contact points, and angle of your
wrist. Now grip it with your hand angled so that the pinky/pommel
end would be angled upwards. Try the motion again.

I found two interesting things:

1) To get the most blade to come in contact with the 'wood', thus what
I think would be to maximize each chop, it should be parallel to the
ground or 'wood'.

2) The most fluid, comfortable, and I think powerful, motion ended
when my wrist was straight in line with my forearm. As when you throw
a punch, the wrist is neither crooked up or down.

When holding the ruler (or mockup) as I would a straight handled
knife, the angle was all wrong. With my wrist straight, just a small
portion of the blade would come in contact with the 'wood'. It
seemed inefficient. It came down at a tip first angle and not
parallel to the item. To get the blade parallel my wrist had to be
crooked upwards and my elbow seemed to be hyperextending. It was
awkward, and felt like I had less power. To avoid that I had to
extend my reach outwards about a foot infront of me, which felt very
unsafe, and placed more strain on my back.

To resolve both those problems, I found that by holding the blade
parallel near the ground, the handle should be angled up twoards the
pommel so that the wrist/arm remain in line. I would venture to say
that the ideal angle would be a factor of several things like blade
length, an individual's swing, chopping positions, etc. etc. Mike S.
mentioned a 15-20 degree angle. I would say that even more might be
good for low to the ground chopping. Though, just a slight 10-15
degree angle would make it more versitile in other positions.

Interesting stuff. I wonder how this would play out in a real knife?


Mike H.
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Don Robinson

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Sep 15, 1997, 3:00:00 AM9/15/97
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Interesting thoughts. You are probably right.
But can you imagine how awkward this knife would look? I'd hate to try to
sell it.
Regards,
Don Robinson
http://home.att.net/~don.robinson.cutting.edge/robinson.htm

Mike H. <nospam...@tiac.net> wrote in article
<5vjguk$4...@news-central.tiac.net>...

Carl J. Paulsen

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Sep 15, 1997, 3:00:00 AM9/15/97
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I think I missed something, as I'm not too sure what it's supposed to be
shaped like.
Curved up?

Carl.


TonofFun

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Sep 16, 1997, 3:00:00 AM9/16/97
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What he's getting at is taking advantage of the natural angle that a human
hand will hold an object at. Pardon the lousy artwork, but if you grab
hold of a flashlight, or a machete handle and look at what your hand is
doing, it should look more like figure A than figure B.

He's saying that for your machete swing to bite into the most wood and do
the most work, it needs to contact the material with the blade parallel to
the ground. If you try and hold a regular machete so that the blade is
parallel to the ground when your arm reaches it lowest point (i.e. figure
B) you either have to crook your wrist uncomfortably, or have to loosen
your grip so that pretty much only the thumb and index finger are gripping
the handle. Neither of which is a good idea.

--
Rob Casler
rob at casler dot com

Carl J. Paulsen <cjpa...@usa.net> wrote in article
<341DCBFE...@usa.net>...

begin 600 humnhand.bmp
<encoded_portion_removed>
end


Michael Koblic

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Sep 16, 1997, 3:00:00 AM9/16/97
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In article <5vhtir$s...@camel3.mindspring.com>, mi*a...@cphl.mindspring.com
says...


>
>This post has a little to do with physics, a little to do with
>descending arcs, momentum, and a good bit of admitted speculation

>based on what I've seen so far. Don Paul, lays out a seemingly perfectly

reasonable sounding
>theory that since Inertia equals mass times velocity, then one can
>double the effectiveness of one's chopper by merely doubling the
>weight of the blade.

I will not dispute your practical experience.

From theoretical point of view, however, rather than inertia one should
consider transfer of ENERGY, which equals mass times velocity SQUARED (NB
rifle bullets), i.e. the main factor should be the velocity with which the
cutting implement is swung.

I wonder if the better results you got with the 18" machettes is because they
are much faster to swing than anything else in your arsenal. I have recently
done some calculations for golf clubs and tennis rackets with longer handles
which are quite interesting in this respect.

The other factor I thought might be the way the weight is distributed, i.e.
the effective mass.

There must be an optimal angle of the edge: too thin will bind in the wood
early, too thick will just not penetrate to any depth.

I was interested in your comments about the shape of the handles: presumably
there is good reason why the better axes have shaped handles rather than
straight ones like sledge hammers. Looking at the kukri handle, I think it is
less tiring to use due to the angle of the wrist, but one will loose a
portion of the swing arc due to the angle of the blade.

I must get some of my blades out (different to yours) and try this in
practice, rather than just blow hot air.

I do find your posts fascinating!

Mike Koblic,
Quesnel BC


TonofFun

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Sep 16, 1997, 3:00:00 AM9/16/97
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I think this is kind of what he means... I've seen snow shovels with
handles kind of like this.

Now realize that a handle of this sort would only be helpful for chopping
things near your feet. If you were chopping at chest or waist level, a
straight handle would be fine. If you were chopping primarily overhead,
you'd want the handle bent the opposite way.

--
Rob Casler
rob at casler dot com

Carl J. Paulsen <cjpa...@usa.net> wrote in article
<341DCBFE...@usa.net>...
> I think I missed something, as I'm not too sure what it's supposed to be
> shaped like.
> Curved up?
>
> Carl.
>
>

begin 600 handle.bmp
<encoded_portion_removed>
end


Mike H.

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Sep 16, 1997, 3:00:00 AM9/16/97
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"TonofFun" <sp...@spam.spam> wrote:
>Now realize that a handle of this sort would only be helpful for chopping
>things near your feet. If you were chopping at chest or waist level, a
>straight handle would be fine. If you were chopping primarily overhead,
>you'd want the handle bent the opposite way.
>Rob Casler
>rob at casler dot com

Yes! The ideal handle angle would depend on how you were coming at the
item to be chopped - ie, the angle of your wrist/arm that allows the
blade to be parallel. If the tools' primary use would be hacking
through bush to clear a path, then maybe a straight or angled down
handle would be best.

Here is my solution... a handle that can be locked/unlocked near the
hilt and racheted up or down to the angle that we need! Should be
pretty easy to do. Any patent attorneys out there?

--
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Mike P. Swaim

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Sep 16, 1997, 3:00:00 AM9/16/97
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"Marvin Edgeworth" <ed...@ibm.net> wrote:

> Dear Mr. Swaim,
> Yes, I see what you're getting at. I believe you recommend the Ontario
>ON-18 machete, $15.95 at the KnifeCenter (please correct me if I'm wrong).
>If that's correct, I'll get one and try it out in a test with the SP-8.

Hmm, recommend is a different word from what I might use. It's one
that I like alot. Perhaps you'd like it too. Who knows? Smokey Mtn.
lists it as MA1 for $13.99 wout/sheath and + sh.

> Test may not be immediate - wife scrogged her knee, so I've been staying
>close to home the last little while. )

Speaking of different wording, I'm interested in reading that you're
wife "scrogged" her knee. I've heard the term used as a euphimism for
concentual sex, but never as an injury. Looking it up in the Webster's
Encyclopedic Unabridged Dictionary, I see that it's listed as a
Northern English or Scotish term referring to stunted bushes and
trees.

So lemme see, One could scrog one's knee while scrogging in the
scrogs. Ain't language great? ;-) Or I guess you could use your
machete to cut a blackthorn staff from the scrogs?

MPS

Mike P. Swaim

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Sep 16, 1997, 3:00:00 AM9/16/97
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mko...@uniserve.com (Michael Koblic) wrote:

>From theoretical point of view, however, rather than inertia one should
>consider transfer of ENERGY, which equals mass times velocity SQUARED (NB
>rifle bullets), i.e. the main factor should be the velocity with which the
>cutting implement is swung.

The answer lies in the phrase "transfer of energy". Only in the case
of one-hand choppers, maybe the concept should be altered to most
cutting area delivered on target per swing.

>I wonder if the better results you got with the 18" machettes is because they
>are much faster to swing than anything else in your arsenal.

I seriously doubt if there is all _that_ much difference in a simple
one-hand downward swing between a 1lb. object and a 2lb. object. Keep
in mind that both objects are basically falling towards target, rather
than being propelled at speeds at which standard ballistics tables and
figuring rates might apply. (The slowest true ballisitics software
that I have, out of several different programs, mentions totally
unreliability below 300fps. A one-hand chop is definitely much slower
than that. ;-)

>The other factor I thought might be the way the weight is distributed, i.e.
>the effective mass.

How 'bout the way the edge is distributed? Not to make jest of total
weight distribution, because it is important. Perhaps the key phrase
is "effective edge"? Since to one degree or another the other mass is
somewhat extraneous, except as it transfers arm energy into cutting
energy.

>There must be an optimal angle of the edge: too thin will bind in the wood
>early, too thick will just not penetrate to any depth.

That's clearly something that needs a lot more in depth coverage.
Interestingly, my concern over "too thin" an edge, is not so much that
it'll bind, but rather that it tends to get destroyed too early. I
probably need to write up something on kindling splitting and see how
it compares to the experiences of folks that really split alot of
kindling, but my basic premise is that if you're splitting kindling
with a one-hand chopper, you're likely doing most of it by pounding
not chopping, since very rarely have I had any kind of one-hander
split clean through on the first chop.

The mere nature of the tools tends to mean that the first kindling
splitting stroke is more to set the blade into the wood than cleave
it. (As perhaps different from a two hand splitter.) The rest of the
strokes are often either to pound the wood and tool as one into the
ground or splitting block, or to hammer the tool through the wood with
a secondary tool device. Either way, the rapid swelling of the hatchet
head tends to bind _more_ in any but the driest of hardwoods, than
does the thinner, flatter machete, or bowie which can simply be
pounded through with another "pounding " tool.(stick)

The thin profile tends to cut it's way through, whereas the rapidly
enlarging wedge profile tends to force it's way through, if it can't
rather immediately find a very dry and willing grain structure to coax
into submission early on.

>I was interested in your comments about the shape of the handles: presumably
>there is good reason why the better axes have shaped handles rather than
>straight ones like sledge hammers. Looking at the kukri handle, I think it is
>less tiring to use due to the angle of the wrist, but one will loose a
>portion of the swing arc due to the angle of the blade.

I'm not sure if this is right, but the way that I think it works, is
the better of the curved handles put the hand more in line with the
"center of percussion", (sweet spot on the blade), and less in line
with the "line of impulse", (line through center of handle section
extending out through the tip of the tool). It's kinda hard to
explain, and I'm not even sure that I really get it, but I'm getting
to where I think I can see it and draw it, just not explain it very
well.


MPS-- remove asterisk in email address to email me


Mike P. Swaim

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Sep 16, 1997, 3:00:00 AM9/16/97
to

nospam...@tiac.net (Mike H.) wrote:

>Yes! The ideal handle angle would depend on how you were coming at the
>item to be chopped - ie, the angle of your wrist/arm that allows the
>blade to be parallel.

>Here is my solution... a handle that can be locked/unlocked near the


>hilt and racheted up or down to the angle that we need! Should be
>pretty easy to do. Any patent attorneys out there?

Why not just use a fixed handle curved like a bananna to facilitate
different grips for different angles or circumstances?


MPS


Marvin Edgeworth

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Sep 16, 1997, 3:00:00 AM9/16/97
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From
http://work.ucsd.edu:5141/cgi-bin/http_webster?isindex=scrog
I get the definition
\Scrog\, n. [Cf. Scrag, or Gael. sgrogag anything shriveled, from sgrag to
compress, shrivel.] A stunted shrub, bush, or branch. [Prov. Eng. & Scot.]
which pretty well goes along with your definition. I have heard 'scrogged'
used as military slang for 'damaged body part', possibly coming from the
'shriveled' portion of the definition.
And thanks for the tip about Smokey Mountain.


Mike P. Swaim wrote in article
<5vmu64$5...@camel4.mindspring.com>...>Speaking of different wording, I'm

Michael Koblic

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Sep 17, 1997, 3:00:00 AM9/17/97
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>
>I seriously doubt if there is all _that_ much difference in a simple
>one-hand downward swing between a 1lb. object and a 2lb. object. Keep
>in mind that both objects are basically falling towards target, rather
>than being propelled at speeds at which standard ballistics tables and
>figuring rates might apply. (The slowest true ballisitics software
>that I have, out of several different programs, mentions totally
>unreliability below 300fps. A one-hand chop is definitely much slower
>than that. ;-)
>
>
The limited studies I did with the golf clubs show appreciable differences in
clubhead speeds depending on length and weight (let alone the mode of swing,
which is the most important determinant of the final result. Do you chop with
your writ, forearm, the whole arm or do you put some "body" into it? Do you
do it consistently?)

I am thinking of buying a tennis chronny to test this out. I guess if one
were to eliminate the human element one should borrow the Iron Byron!

Mike Koblic
Quesnel BC


Mike H.

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Sep 17, 1997, 3:00:00 AM9/17/97
to

mi*a...@cphl.mindspring.com (Mike P. Swaim) wrote:

>Why not just use a fixed handle curved like a bananna to facilitate
>different grips for different angles or circumstances?
>MPS

If I understand you correctly then I think the blade would need to be
sharpened and functional on both sides. Holding the handle curved
down, using the "inner" edge, you would use it for overhead/high
swings. Holding the handle curved upward, using the "outer" edge,
you would use it for downward/low chops. Is that correct?
If so, its an interesting idea, but much to simple to ever work ;)
I was hoping maybe a micorprocessor controlled, variable angle, sensor
riddled thingy that would develop intelligence about the users size,
swing, force, etc. to automatically find the best angle....

Using the banana handle, double edger would require some additional
thought as to the ideal grind for each edge. I don't know the
technical knifemaking terms so stick with me on this. Would a
flat/conves grind best on low chop side, hollow on the high cut side,
or what? I like to complicate things as much as possible. Where
would the blade be thickest? In the center it which might create too
thick of a wedge for one or the other type of chop. Or, would the
grind lines be off-center so that maybe the flat side is 3/4 of the
depth and the hollow side is the remaining 1/4 depth?

Gonna have to break out the cardboard again....

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