CS Recon Tanto vs Birch log. Winner: Birch log

[Gryffin]

FWIW, my Recon Tanto was more "tip down" when it broke.

Well, so much for Sharpshooter's and MikeStewart's theory that the angle was the sole culprit, huh?

 

[Gryffin]

Here is a link to an interesting thread regarding batoning, knife failures and the dreaded fulcrum. . .
http://www.knifeforums.com/ubbthrea...ber=568643&page=&view=&sb=5&o=&fpart=all&vc=1

How accurate are the physics arguments being presented?

Not sure if this was aimed at me or Cliff, especially since Cliff addressed it already. But I took a look at the thread, diagrams, vitriol and all.

The thing that bugs me about Sharpshooter's and MikeStewart's arguments is the insistence that the ~20° upward cant of the spine was the single, solitary cause of the knife's demise. I don't know Sharpshooter, and I have a lot of respect for Mike Stewart, but from an engineering standpoint, it looks like hogwash. That small an angle just shouldn't change the forces that drastically.

One detail in Sharpshooter's first diagram is interesting, though:

He makes the mistake of assuming that the knife is just entering the log, hence *all* the force is being applied at the fulcrum, near the tang. The photo of the failed knife is quite different: the blade has already penetrated almost it's entire width.

So, what's the difference? Well, in the latter (real failure) case, there's no single point fulcrum. The blade is wedged in the split; the resisting force is distributed across the width of the split. In fact, the force isn't even at the edge; with a 1/4" thick blade, like the Recon Scout, the spine of the blade is taking the brunt of the force, with the wood splitting ahead of the edge, as mentioned in the Chudinski review you quoted.

Assuming a perfectly straight-grained wood, with perfectly consistent density and strength throughout, and a perfectly-formed split, the force on the blade *would* be somewhat higher at the lower end of the blade, as it's wedged deeper into the split, and hence under more pressure from the surrounding wood. So if the handle was lower than the tip, the total resisting force of the wood *would* be closer to the guard, which would increase the stress on the tang. So Sharpshooter is partially correct, in theory.

However, wood just isn't that consistent a material. IMHO, variations in the wood itself would have a greater influence on the distribution of forces on the blade than would the angle of the handle, at least at the relatively small angles seen here.

In summary, the real culprit is still a bit of a mystery. Lots of ideas hurled out there, but none that really hold up.

If you want my considered engineering opinion, I suspect the real culprits to be:

• A too-sharp transition between tang and blade, and/or poor heat treat, leaving the tang weakened
• The operator pushing on the handle while batoning, creating stress in the tang

I agree with Cliff that a properly formed and heat treated carbon-steel blade shouldn't fail like that Recon Scout did, even if batoned with a tree trunk; and I agree with Mike Stewart that pressure on the handle at the time of baton impact puts unnecessary stress on the tang. Neither factor alone could have caused the failure, but both together certainly could.

 

[knifetester]

Ahhhh, the dreaded fulcrum. I am sooo glad one of my knives saw that, they would flee with fear.

Not sure if this was aimed at me or Cliff

Totally open question of course, just looking for a knowldgeable, informed opinion. Thank you for input.

from an engineering standpoint, it looks like hogwash.

Yeah, that's pretty much what I figured. Kinda of a cool drawing though.

I agree with Cliff that a properly formed and heat treated carbon-steel blade shouldn't fail like that Recon Scout did, even if batoned with a tree trunk

So do I.

I agree with Mike Stewart that pressure on the handle at the time of baton impact puts unnecessary stress on the tang.

I have seen people hand off knives that are supposed to be much less durable. See Cliff's brother and the SRKW Howling Rat for example.

Mike Stewart is simply wrong. Operator error was not the likely cause of this breakage, design and execution are the most likely culprits.

Tip up/ tip down, dreaded fulcrums and all other hogwash aside. A well built knife should easily be able to accomplish splitting. It should not even be an issue.

 

[sodak]

For knives that are this overbuilt, they should be able to take any type of batoning with wood into wood, even if the wood is frozen. No if, ands, or buts. The fulcrum arguments are probably correct, but the stresses involved shouldn't be coming close to breaking this knife. I have both of these models, and have treated them much worse with no problems. That should be the expected behavior.

 

[Cliff Stamp]

• The operator pushing on the handle while batoning, creating stress in the tang

You can't split much beyond clear, straight grained wood without leaning heavily into the handle, otherwise there is no countertorque and the blade just rotates into the wood.

....dreaded fulcrums and all other hogwash aside.

The fulcrum point is actually critically important to the shear strain on the tang/handle joint but it has nothing to do with the angle of the blade but the distance from that point to the rotation point. The interal stress is a maximum at the point of rotation and decreases to zero at the two end points, therefore the closer the tang/blade junction is to the wood the greater stress it will be under.

Thus for example a puukko will break long before a leuko
[*], because with a leuko the tang/blade juncture can be kept far away from the point of rotation. With this in mind for example the worst setup would be a knot at the far point of a round and the handle placed right against that. However from a user point of view, the conditions for maximum stress on the knife are also the same as those that make maximum splitting efficiency.

For example with the knotty round example just used, if instead the handle is placed against the other side of the wood the tang/blade juncture will see far less stress, but you will find it much harder to actually split the wood for pretty much the exact same mechanical reasons. One of the reasons you buy better tools is to increase efficiency.

Of course when splitting woods you seeks blade placement so as to maximize splitting power which means you avoid chisel cutting knots if at all possible and try to work around natural cracks in the wood. This isn't to prevent the blade from breaking of course, it is to make life easier on you. If you want/need the exercise it is one thing, but aside from that work smarter not harder.

-Cliff

[*] there is a further complication, this statement assumes you are strong enough to prevent both blades from rotating under impact, if you are not then the leuko will see more stress because of the leverage advantage, this usually isn't an issue however as it is trivial to do a shoulder lock and put pretty much all bodyweight into the handle if necessary

 

[Gryffin]

You can't split much beyond clear, straight grained wood without leaning heavily into the handle, otherwise there is no countertorque and the blade just rotates into the wood.

My understanding of proper technique that you should hold the handle loosely, just to steady the knife; baton the tip end, driving it into the split and, yes, rotating it; then pushing down on the handle AFTER the impact, to further split the wood and straighten the blade; repeat until split. Pushing down on the handle DURING impact is a big no-no. Or, at least, that's how I was taught, and from what I've seen, still recommended practice.

 

[Cliff Stamp]

If the grain is twisted, if it is knotty, especially ring knots, no progress will be made without exerting a countertorque, this is what allows the impact energy to be directed down into the wood rather than act to rotate the blade. Yes, this does greatly raise the internal torques on the blade but it isn't something a quality knife should be concerned with. If you have to do work with a suspect blade however it would be a way to minimize the chance of cracking.

-Cliff

 

[brianNH]

I know I'm a new guy here, and I dont mean any disrespect, but for the love of god Foxhole, would you just call Cold Steel?

Also, Is it "fashionable" to split large logs with a knife blade? Why not just use a "camp axe"?

 

[Planterz]

Also, Is it "fashionable" to split large logs with a knife blade? Why not just use a "camp axe"?

One less thing to carry.

 

[Cliff Stamp]

Also, Is it "fashionable" to split large logs with a knife blade?

No, but those are not large logs.

Why not just use a "camp axe"?

It is actually faster to use a long knife on problematic wood of that size, unless you have a dedicated maul.

It is also not something that should bother a quality knife, considering the baton is made out of wood, it should go before the knife :

http://www.swampratknifeworks.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=10;t=003040

Some of this wood would be very hard to cleave with an axe :

http://i15.photobucket.com/albums/a399/SquirrelSniper/2.jpg

It is also a lot safer with a blade as the axe and turn/glance, especially on knots and twisted grain and especially on wood of that size.

It only takes one maker/manufacturer willing to note it isn't abuse for everyone who claims otherwise to thus promote an inferior product.

Buy better knives.

-Cliff

 

[brianNH]

Cliff - Thanks for the comprehensive and informative reply. I understand a little better now.

I am not a huge fan of the CS products and I am less of a fan of their customer service. I understand they advertise their products as super tough and reliable, however let's be realistic. It's still a $43 knife. Are we expecting too much out of it, specifically the circumstances which cause the original posters knife to break? Is the Tanto design even good for that purpose?

Thanks again,
Brian

 

[yoda4561]

No you aren't expecting too much, I'll take any 40 dollar Camillus made Becker and happily baton away, I have a few smaller hand forged fixed blades (around 40 dollars) that while not good on large wood, are 100 percent reliable in that sort of use. I've also done this with a large mild steel bowie that I made a while back when I first tried to forge a knife, mild steel mind you, I made it with a stick tang, mildly radiused the tang corners, and yeah, it batons fine, no breakage and no bending during batoning either, though it does bend if you pull on the handle laterally fairly easily.

Edit: I actually have an old recon tanto, and have batoned on it before just to see how well it would work, it's actually a fairly nice design for this, as the spin is fairly thick out to the point, so the baton doesn't get messed up by a sharp spine, and the edge similarly is wide and radiused enough to bite into the wood a little, after which the thick grind tends to wedge it apart easily. At no time batoning a knife have I ever felt the tang of all things was liable to break, I'm not beating on them with a baseball bat at full power here, it's usually just mild swings from the shoulder.

 

[sodak]

Cliff - Thanks for the comprehensive and informative reply. I understand a little better now.

I am not a huge fan of the CS products and I am less of a fan of their customer service. I understand they advertise their products as super tough and reliable, however let's be realistic. It's still a $43 knife. Are we expecting too much out of it, specifically the circumstances which cause the original posters knife to break? Is the Tanto design even good for that purpose?

Thanks again,
Brian

I understand your feelings about the CS, but no, this is definitely *not* expecting too much. These knives are promoted for more extreme use than this, and this one in particular is quite overbuilt for this kind of treatment. I agree with Cliff, if it fails, buy a better knife. Mine so far haven't failed at this, and worse abuse, but if they did, I would not hesitate to get something else.

 

[Cliff Stamp]

... be realistic. It's still a $43 knife. Are we expecting too much out of it...

You can easily get a $10 machete which will take heavy batoning, so no, I don't think it is unreasonable. That isn't a very high standard to aim for either.

-Cliff

 

[STR]

I always thought the hump of the Nesmuk blade, along with what Gryffin said, was to add a bit of tip heavy weight to an otherwise smaller knife to allow it to do well at some chopping tasks others in its class would be hard pressed to do.

I was told once by a good ole boy that the design was particularly good for big game field dressing because the hump allowed a convenient place that stuck out on the blade to baton the knife through the breast plate when angled just the right way and that always made sense to me since that is the history of the blade during the big time buffalo hunting days when those style of knives were most popular.

 

[TLM]

I don't remember if it has been said or not but all the pictures I have seen of these broken knives show no plastic deformation whatsoever. Using Occam's razor that means: wrong geometry coupled with wrong temper for that particular material. There are some other possible reasons but they are not very likely.

TLM

 

[the possum]

So it seems generally known and accepted that it's a bad idea to make the tang/ricasso area with sharp corners. I agree. At the very least, you could say this construction method is less than ideal, especially when it's just so easy to leave the corners rounded.

Yet...
Not too long ago in one of the knife magazines, there was an article about a guy making a hard use knife. The pictures and description clearly showed sharp & square corners in this very place.

When makers learn stuff at smithing schools, one-on-one instruction, hammer-ins, etc., does no one ever cover things like basic design principles and theory? Are they too busy learning the technicalities of shaping metal that they don't have time for design?

 

[Cliff Stamp]

So it seems generally known and accepted ....

It isn't, that is the problem. Spend some time on Knifeforums and read comments by Stewart and company who argue the above knife is perfectly fine and it broke through abuse due to ignorance of the user.

As long as there are people willing to accept this knives of such standards will continue to be made and sold. I find it interesting that the idea can propogate even in the face of other makers publically stating it is false.

Swamp Rat and Busse Combat have both publically noted this is not abusive, but still the idea persists.

-Cliff

 

[Gryffin]

So it seems generally known and accepted that it's a bad idea to make the tang/ricasso area with sharp corners. ... Are they too busy learning the technicalities of shaping metal that they don't have time for design?

Well, it's well-understood in engineering circles, at least. Problem is, knifemakers are craftsmen, and usually don't have a formal background in engineering, so many of them apparently don't know. Read on...

I agree. At the very least, you could say this construction method is less than ideal, especially when it's just so easy to leave the corners rounded.

Well, actually, it's easier to cut the corners sharp. On the edge of the grinder belt (or stone or mill or file), you just grind down the edge of the stock to reduce from the blade width to the tang width. Getting a good inside radius requires more work, with a round file or radiused stone or similar.

Another reason to leave a sharp corner, is to make it easier to fit a simple sheet-stock guard. If that inside corner is properly radiused, the maker has to grind the opening in the guard to make room for the radius. Again, more work.

Not too long ago in one of the knife magazines, there was an article about a guy making a hard use knife. The pictures and description clearly showed sharp & square corners in this very place.

Keep in mind, a sharp corner there doens't mean a blade will fail there, it just makes it more likely. Especially if that corner picks up internal stresses from heat treatment, which is hard to predict. Cold Steel has sold a lot of knives, and as far as I can tell, only a small number have failed.

Again, a sharp tang junction won't make a knife fail automatically, it just makes it more likely. However, if that corner was properly radiused, it would be a lot less likely to fail.

 

[Thomas Linton]

IIRC, the "abuse" was driving the knife into the log, pushing the handle down and holding it firmly, and striking the tip of the knife with the baton. This turns almost the full length of the blade into a lever arm, multiplying the stress on the blade-tang junction. <EDIT: This also decreases the friction between the side of the blade and the wood since you a rocking the blade out of the cut. I am informed that the tests made of this theory were repeated on different knives from different makers, and the knives consistently broke in the same fashion when "abused" in this manner.>


I had a Marine survival instructor in Barstow demonstrate this technique as one to avoid when using a GI "KA-Bar" years ago (It broke very nicely indeed.). (Of course, they were the product of the lowest bidder.)

The BRKT Forum commonly speaks of batoning as normal use of BRKT -- and other's -- products.

I note that quite a point was made on the BRKT forum, without prompting, that all corners in a newer, skeletonized- handle BRKT model had been radiused.

Many makers are reluctant to make critical comments on the products of others, and some makers glory in attacking the work of others (and their morals, honesty and taste in beer). For me, that behavior helps justify independent, objective testing.

$.02