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"Unlimited Class" Competition chopper


Geoff Keyes

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I've been watching the TV show Knife or Death. I've cast my design eye on the knives/swords being used, and I think I've noticed something, a convergence of style. The long blades (26 inches and longer) don't work as well as as ones in the 16-20 inch range. The compchoppers work well, but since they are limited to 10 inches, they are too short for some of the cuts. The longer blades are too light and flexible to withstand the heavy cuts. If there is anyone looking for a blade for the show (or related "unlimited" class cutting) I'd like to talk to you about just such a tool.

I've been working up some designs.  If other folks here also have thoughts, I'd like to see them.

Geoff

"The worst day smithing is better than the best day working for someone else."

 

I said that.

 

If a thing is worth doing, it is worth doing badly.

- - -G. K. Chesterton

 

So, just for the record: the fact that it does work still should not be taken as definitive proof that you are not crazy.

 

Grant Sarver

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I havent seen the show but I have some theories about cutting, I have made knives in lots of sizes and shapes though im limited to around 12" at the longest, though i have used 1/4 and 1/6 scale katana and naginata for cutting and they dont work right if they arent made right.

The most important thing in cutting is how the blade tracks through the cut, your movement might be perfectly in line with the cut but a longer blade might flex and twist, when that happens you are applying force to the target from the side of the edge of the blade which twists it more. This will happen with any misaligned cut, the cut will be curved.

Im wondering if a full flat grind would track better than a convex edge, while the convex edge can move material out of the way of the rest of the blade it can also move the blade out of alignment, think of western style kitchen knives compared to japanese kitchen knives.

After blade tracking you have to consider speed and mass, more mass further out is harder to swing, not enough material could mean more twisting in the blade. If the blade is too light your body could move too fast, you want cutting to be a smooth operation, the blade needs to be comfortable to swing, you and the blade need to be able to move together. 

A reverse distal taper puts mass where you want it and is lighter than a non tapered blade, naginata can have long blades and handles, there is a lot of leverage against the blade that way. Just switch the leverage force from a long handle to extra force from a heavier blade, we say things that work dont get changed, I would look into naginata or naginata-naoshi geometries because that might be the highest force application of a hand held knife/sword blade.

However with a reversed distal taper you could end up with flex nearer to the handle which would be very bad as everything past the flexed area is not in line with the cut, I have noticed that many naginata have a fuller for the first 1/3 - 1/2 of the blade and then the rest is hira-zakuri (I need to check that but my tablet might delete all this if I leave this page) the blade type that is most common on katana. 

I wonder if a double bevel single edge (think katana) would better resist twisting than a ridgeless design.

Dan keffeler (keffler?) Has made some mean chopping katana but I dont know if they are tapered, I do know a non tapered blade is prone to flexing and failing cuts, I have learned this with my miniature katanas.

Perhaps a chopper should push the blade through the target while a fighting knife of sword needs to be pulled through. You dont pull an axe so it slices you swing it out so it chops. 

The way you move when cutting is also very important, you need to be at the optimum distance and you need to move with the cut, I have found that stepping into a movement helps my alignment with my knives, my slingshots, and my rifle. 

Bad body alignment is bad blade alignment, period.

Edited by steven smith
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I've watched and I think, snarky thoughts aside, that it simply points out some basic physics in action. The long blades, coming up against a hard target demonstrates the principle of the lever and fulcrum. Unfortunately for the blade the closer to the handle the fulcrum (that being the object to be cut) the more leverage is applied to the "free" end of the blade. It is the same effect when you bend a hot blade over the horn of the anvil intending to bend it. No surprise many blades fail.

As far as blade geometry is concerned I would opt for a convex edge with a lenticular blade cross section. This would put the thickest, hence strongest, portion of the blade closer to the edge and would also mean that the thickest portion would encounter the target earlier in the velocity loss curve, as it were, meaning a tiny bit more velocity and also less drag/friction from the thinner spine side.

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I'm thinking a full flat grind, with a steep reverse bevel the full length of the spine.  On a Katana this allows the blade to be a bit thicker and still glide through a cut.  The blade would be thick and stiff, without a point, putting most of the mass forward, right over the COP.  Lengthen the blade to make the longer cuts (like through a 5 gallon water jug) a single hit .  Cant the handle down just a bit and lengthen it, so that a two handed grip is doable, but with good index surfaces'  Light enough the a one handed cut and recovery can be done, at least early in a run, but making a transition to a two handed cut easy.

In the show (and we haven't seen a final run yet), most of the cut are power cuts against difficult targets.  The blade needs to be light enough to flick through hanging slabs of boneless meat, but strong enough to chop through blocks of ice.

 

I have two designs in mind, a dha like curved blade with a long handle, and a bolo/yatagan, weight forward, design with a long handle.  A straight edge reverse curve is a good chopper, but less of a slicer, IMHO.

 

Geoff

"The worst day smithing is better than the best day working for someone else."

 

I said that.

 

If a thing is worth doing, it is worth doing badly.

- - -G. K. Chesterton

 

So, just for the record: the fact that it does work still should not be taken as definitive proof that you are not crazy.

 

Grant Sarver

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The only stock I got that can go beyond 3/16" thick are 3/4" W1 rounds. So, let's say, 11" long 1.25" wide, 1/4" thick at spine full flat grind, going slightly convex near the edge to almost zero. Does that sound right?

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I haven’t seen the show, nor am I very good with blade geometry. But my first thought is a kukri with a flat grind, used by the Gurkha’s of Nepal for survival purposes, and slicing arms clean off! 

Mason

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Longer, and a bit wider I think.  Say 16"-20" of blade, no point (unless they add a stabby test) and maybe close on 2" wide.  A nagamaki is too long, more on the order of this

s-l1600.jpg

But stiffer and in better steel, with a bit of cant to the handle.  The Prince's sword from Hellboy 2 (without all of the movie gimmicks).  I'm still refining my design.  I should have a drawing in the next day or so.

Geoff 

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"The worst day smithing is better than the best day working for someone else."

 

I said that.

 

If a thing is worth doing, it is worth doing badly.

- - -G. K. Chesterton

 

So, just for the record: the fact that it does work still should not be taken as definitive proof that you are not crazy.

 

Grant Sarver

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http://www.koldsmoke.com/2011/01/cloud-cutter/

Several people I have talked to think this is the best-cutting blade there ever was.  I know Don and Jimmy were so impressed with it they made a template of the cross section in the sweet spot so they could replicate the geometry.  I got to hold it once, but I couldn't cut anything since we were indoors.

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Cloud Cutter without the back edge is my thought, almost exactly.  Cloud Cutter still haunts my dreams.

Cloud-Cutter-Illaa.jpg

I also found this little gem, apparently a head hunters sword

2016-3_WM_451.JPG

2016-3_WM_455.JPG

Geoff

 

"The worst day smithing is better than the best day working for someone else."

 

I said that.

 

If a thing is worth doing, it is worth doing badly.

- - -G. K. Chesterton

 

So, just for the record: the fact that it does work still should not be taken as definitive proof that you are not crazy.

 

Grant Sarver

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1 hour ago, Stuart Samuel said:

How think is Cloud Cutter, Alan? (If you recall)

It's been ten or more years, but I seem to recall it being rather thin.  Like maybe 1/4" at the turk's head, tapering quickly down the hamon to maybe 1/8" at the end of the hamon.  I do remember it was 0.026" thick 3/8" in from the edge.  The template Don and Jimmy made was by chopping it into a sheet of copper.

At any rate the way it handled was unreal.  :ph34r:

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I watched some of the show, forged in fire was really cringy to me because of the time doug slapped a dead pig in the ass with a un hardened claymore and it bent but the maker was able to do the cut.

Plastic buckets were hard for some, I think its because they were cutting down and glancing off due to the slope of the buckets, cutting up would dig the edge into the slope of the bucket. 

They chopped up a crate which is nothing too crazy but people were getting tired?  You can swing a knife too hard and fast, nobody did when they came up against a big fish though...

Im thinking full tang naginata naoshi with a little recurve and the tip forged out like if you had an axe edge you could thrust with to catch and shred anything that slides off the blade with a sharpened spine. Does a split tip with an edge curving up and the other curving down sound good? You could have it split or with material betwen the tips. 

it is very good practice to cut sticks and branches because of the odd cutting angles, you have to move around and you need a sharp edge to cut small twigs and leaves without tearing them. 

I would be screaming and running around the course, like I used to do at large bicycle rides.

My blade, antenna, 

Catch light, Shine,

through opacity. 

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4 hours ago, Alan Longmire said:

It's been ten or more years, but I seem to recall it being rather thin.  Like maybe 1/4" at the turk's head, tapering quickly down the hamon to maybe 1/8" at the end of the hamon.  I do remember it was 0.026" thick 3/8" in from the edge.  The template Don and Jimmy made was by chopping it into a sheet of copper.

At any rate the way it handled was unreal.  :ph34r:

That's about what I pictured, as far as that central ridge. That edge sounds wicked thin, though. :D

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Couple things that surprise me about that show. The absolute junk knives that are showing up. More than a few! I would have expected a bit less ebay pakistan steel to be showing up. The other thing that surprises me is that a lot of the competitors dont work within the strengths and weakness of their selected blade at each stage. It also seems odd that they let swords compete against knives too.

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There have just been the 2 episodes so far (or is it 3).  I am amazed at the junk, there are clearly a bunch of folks who don't know anything about blades out there.  The Comp Cutting world comes from the ABS testing world, and they have the same blade size specs.  This is why I called the thread "Unlimited" class, since the show decided to let everyone play.  In fact, so far, the swords have not done well.  Some of the failures have been in workmanship (the falchion), the two katana have bent.  The comp cutters are good, but not long enough for some of the cuts.  If the show lasts, I think we will seem a move toward a design much like what I'm trying to get to in this thread.  The winners so far have been a big kukri style and a falcata and one (?) other.  We shall see

 

Geoff

"The worst day smithing is better than the best day working for someone else."

 

I said that.

 

If a thing is worth doing, it is worth doing badly.

- - -G. K. Chesterton

 

So, just for the record: the fact that it does work still should not be taken as definitive proof that you are not crazy.

 

Grant Sarver

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While I too am surprised by the same thing you must think about the fact that it is the first season and the shows were "in the can" before anyone saw the "challenges". How they got the competitors I do not know and the "expert" commentators give me cramps. One competitor sounded like he was a member here. He made his sword and, during the safety check detailed the metal and heat treat and referred to it by Oakshott pattern designation. Later one of the "expert" commentators said (as close as I can to an actual quote)

"Oakshott blades are designed for heavy cutting"

:rolleyes:

If anyone remembers the first season of "Survivor" then you saw all I ever watched. When Rudi, the former SEAL washed out because of the game playing I realized the show had little to do with "surviving". Same with a lot of what is on FIF and its new derivative.

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I made a scaled drawing of my idea.  I'm going to call it Leviathan I.  The thing is HUGE.  Even after I lopped 2 inches off the blade it seems unwieldy.  It would cut well, I think, but the one handedness of it seems in doubt.  I'm going to make a 2nd drawing with a different idea and see where that takes me.  PIcs to come.

Geoff

"The worst day smithing is better than the best day working for someone else."

 

I said that.

 

If a thing is worth doing, it is worth doing badly.

- - -G. K. Chesterton

 

So, just for the record: the fact that it does work still should not be taken as definitive proof that you are not crazy.

 

Grant Sarver

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I REALLY like Cloud Cutter. I have questions about its design, if anyone happens to know or wants to speculate. Is it sharpened on both sides? It looks like maybe the edge facing down in the photo cuts like a sword and the other side (if sharpened) would cut like a parang? I can see a lot of value in that design in a competition like we're talking about. Either way, it's now on my list of blade styles to explore and someday learn to replicate. Not to sell or make a profit, but just to cut with it. That thing LOOKS like it wants to bite something.

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If memory serves, it's sharp top and bottom, the top edge is about half of the length of the main edge.  It is essentially lense shaped.  What is the difference between a "swordlike" cutter and a "paranglike" cutter? 

As I remember the folks who got to handle it said it felt like it could "cut a cloud".

Geoff

"The worst day smithing is better than the best day working for someone else."

 

I said that.

 

If a thing is worth doing, it is worth doing badly.

- - -G. K. Chesterton

 

So, just for the record: the fact that it does work still should not be taken as definitive proof that you are not crazy.

 

Grant Sarver

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16 minutes ago, Geoff Keyes said:

If memory serves, it's sharp top and bottom, the top edge is about half of the length of the main edge.  It is essentially lense shaped.  What is the difference between a "swordlike" cutter and a "paranglike" cutter? 

As I remember the folks who got to handle it said it felt like it could "cut a cloud".

Geoff

Yes indeed.  I did a half-hearted search for the original thread, but didn't see it.  It may have gotten lost in one of the crashes over the years.  It is lenticular in section, the back half sharp, and got its name from the cloudlike hamon and the fact that it pretty much embodies the idea of "to cut."

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My thoughts on "parang-like" cutter would mean that it's weight forward at the point of impact, based on the way it would curve when swung in that orientation. It made sense in my head. "Sword-like" cutter wouldn't be as weight forward. 

Maybe "kukri-like" would be a better descriptive question, now that I think about it. Either way, the orientation in the hand would obviously change the geometry. 

Edited by Mike Andriacco
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Here are some line drawings that I have done, the ones on graph paper are pretty much to scale.  My idea is about 9-11 inches of handle, enough for a two hand grip without stacking, but indexed enough to use one handed.  The blades would either have a broad fuller along the spine or a reverse bevel from midline to spine.  They are going to be nose heavy.  This is all bluesky at the moment, unless someone else pushes me.

IMG_1372 (800x533).jpg

IMG_1373 (800x533).jpg

IMG_1376 (800x533).jpg

Geoff

"The worst day smithing is better than the best day working for someone else."

 

I said that.

 

If a thing is worth doing, it is worth doing badly.

- - -G. K. Chesterton

 

So, just for the record: the fact that it does work still should not be taken as definitive proof that you are not crazy.

 

Grant Sarver

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