Let's talk about Trimmed Tangs

[Rick Marchand]

First off... get your mind out of the gutter.

Secondly... I come in peace and with the intentions of learning.

Hidden, Partial, Stick, Rat Tail, etc... I completely understand that when properly executed can "perform" equally well for the majority of conventional "knife tasks" and employ them in many of my own designs. My understanding of features like fullers tells me that you can make compromises in some areas and if done right, can improve the "overall" performance of a blade. However, logic fails me when I have to yield to folks who I consider friends and makers, whom I respect tremendously, when I read/hear statments like "Full tang construction is a thoroughly modern phenomenon, and is a viable, but in no way superior method of construction."

When it comes to balance, handle options and stuff like material conservation, I can substantiate less-than-full tang reasoning with what little I know of material science and from my own practical experience. But when someone makes a claim that they are equal in ALL respects, I can't wrap my head around the physics. How does the removal of material NOT in some way negatively effect the characteristics/properties that govern yield strength, toughness, etc...

Am I not getting it and completely misinformed?... or am I justified in my thinking and should just continue to back off(for the sake of keeping the peace) when someone goes down that road.

And, NO... I am not attacking Nick's blades... lol.

 

[cdent]

...How does the removal of material NOT in some way negatively effect the characteristics/properties that govern yield strength, toughness, etc...

I think a metal wall stud or an 'I' beam are examples of how design can positively affect some of those characteristics. Not thinking it's the same as a knife handle, but maybe the same amount of material can be arranged more efficiently than a bar or rod. If the full tang gets more steel to work with, it may not be an apples to apples comparison. Then again, chances are, more steel would probably weigh more and not able to be made into a similar knife.

 

[tryppyr]

Frankly, I've wondered the same thing, so I'll be tracking this thread.

I'm thinking, however, the answer will end up being nuanced. In other words, it won't be an explanation of how less metal yields more strength. Rather, it will probably be an explanation of how less metal translates into less vibration passed to the hand or some other explanation totally based on physics, but having nothing to do with cutting 2x4s.

 

[Rick Marchand]

I think a metal wall stud or an 'I' beam are examples of how design can positively affect some of those characteristics.

An I-beam is a great example and one that parallels the fuller concept. But ultimately, a solid design would be stronger.... but I do agree that stronger is not always better. Try to build a house with a solid 6"x8"x20ft beam or wield a large Viking sword without a fuller and you'll see the advantages to that kind of trade off.

Frankly, I've wondered the same thing, so I'll be tracking this thread.

I'm thinking, however, the answer will end up being nuanced. In other words, it won't be an explanation of how less metal yields more strength. Rather, it will probably be an explanation of how less metal translates into less vibration passed to the hand or some other explanation totally based on physics, but having nothing to do with cutting 2x4s.

I would like to hear some physics based reasoning. I'm sure vibration dampening plays a part as well.

 

[james terrio]

I hope this doesn't turn into a brouhaha. Some (not many, but a few) people get downright rabid when their preconcieved notions are questioned.
I posed similar thoughts/questions about designing a blade for maximum lateral strength a year or two ago, and got answers from the sane and thoughtful to the just plain silly.
It's pretty clear that if the steel and HT are equal, more is going to be stronger. Now having said that, the way some of us skeletonize and taper our full tangs, there may actually be less steel than in a comparably-sized narrow tang. Just a thought.

 

[Justin King]

I think it comes down to a matter of perspective and experience. It also may come down to the way a maker designs their blades.

For example:
Assuming that we aren't talking about an inherently weak knife, my own experience tells me that if I break a knife, it will be near the tip, where the blade is thin (this is related to my own taste for a nicely tapered tip, a knife can be engineered or simply overbuilt so as to change this whole assumption). Breaking a knife anywhere near the ricasso is/should be a remote possibility unless I am clearly pushing the knife beyond it's limits. By this standard, the tang does not need to be strong enough to equal the strength of the strongest part of the blade, but the part that is most likely to break. This reasoning obviously does not apply to hard-use knives but for many uses it allows options that would not otherwise be possible, without compromising strength under normal use.
Another factor is the sharp transition from a very stiff and rigid ricasso with the suddenly reduced section of many "trimmed tangs". This must be accounted for in any design that will encounter impact or extreme stress, and these applications are naturally where full tang designs offer an advantage.
Historically the reduced tang was often protected from brittle failure by leaving it unhardened, or even forge welding on a wrought iron tang. This is a fact that is largely overlooked in modern knifemaking and makes the historical use of reduced tangs much more sensible, once you take it into account.

 

[Hengelo_77]

Sometimes you see pictures of full tang knives with so many holes drilled in them, you can question if there isn't less steel then a hidden tang.
My guess is that any difference, if there at all, requires forces beyond what a human holding the knife can go trough.

Didn't the full tang become the preferred construction methode in the old days when many cheap short tanged hidden tangs were sold as well?
With a full tang the buyer can see how long the tang is and know for sure.

 

[Rick Marchand]

I hope this doesn't turn into a brouhaha. Some (not many, but a few) people get downright rabid when their preconcieved notions are questioned.

Since preconcieved notions are not the pathway to truth, I hope to shatter as many as possible... myself, included. I have had MANY preconceived notions busted apart and although it was a bit painful at the time, I am better for it.

It's pretty clear that if the steel and HT are equal, more is going to be stronger. Now having said that, the way some of us skeletonize and taper our full tangs, there may actually be less steel than in a comparably-sized narrow tang. Just a thought.

That is pretty much where I am at, James. I feel I have a decent grasp of physical science. Not a deep understanding... but I'm working on it.

 

[james terrio]

Another factor is the sharp transition from a very stiff and rigid ricasso with the suddenly reduced section of many "trimmed tangs".

Yeah, stress risers are always a bad idea. The only broken narrow tangs I've seen had very abrupt shoulders, like you describe.

 

[John Katt]

Here's a thought from a 32 year construction veteran... all I beam construction wood or steel will need extra material at the stress points (squash blocks) so that you don't have a stress fracture and ultimately Structural failure, drill to close to the place were the handle meets the blade and it will fail, remove the material for a hidden tang and it will fail long before a full tang, this is just some basic common sense

As long as we are talking about tensile strength here, the hidden tang knife guys should shot peen their blades, that would increase the strength of the blades buy a fair amount, you can take an ordinary connecting rod that will likely fail at around 6000 rpms and after shot peening will run at 7500 rpms all day, I use to tinker with small block Chevy's back in the day and that was kinda mandatory

 

[javand]

I think you gave yourself some insight there, even if you don't know it.

The question is more one of diminishing returns to me. A 6" i-beam isn't stronger afaik than a piece of 6" solid square stock, but it's is much lighter, cheaper, and more efficient use of material and more than adequate in most tasks it's put to.

One could just as easily be asking if "x" thickness is enough. We could have a prevailing mentality that anything less than 1/4" thick spine is simply inadequate for a knife, since in theory it must be twice as strong and break resistant as an 1/8th inch thick knife no? Hell maybe 1/4 isn't thick enough for a really indestructible knife, better go 1/2" minimum. There definitely seem to be a few popular production makers that believe this mantra.

What about drilled out full tangs? I see tons of semi-skeletonized full tang blanks on makers benches that have dozens of seemingly random sized and layed out holes drilled into the tangs to "lighten" them, and I've got to wonder, without careful planning, if many of these can't in fact be weaker than stick tangs. I make some fully skeletonized tangs, where ultimate weight is a concern, and you can often end up with less material (and thus lighter) than stick tang construction this way, which in this case is the goal.



Knifemakers and knifeusers aren't all the same, but there seem to be some common cultural influences that in the modern era, tend to dictate a philosophy of wanting everything overbuilt, bombproof, indestructible, whatever. Nothing is, and it concerns me that some of us seem unable to see the drawbacks of driving an Abrams Tank to work everyday.


To my mind, overbuilding isn't always a boon, especially once you've already crossed the threshold of being more that suitable for any sane or mildly insane use. After you pass that threshold at the minimum, i feel the focus should be on efficiency and function. Mass, cross sectional thickness, balance, weight, all effect the performance of a knife, and can just as easily become detrimental to its function, as advantageous. Each intended task of a bladed tool may be different, if you want a crowbar with an edge, that's valid, but acknowledge that's what you're making, and don't lie to the suggestable masses and pretend its a better "knife" because it's more "indestructible" than a knife that's built to cut effectively, and be light and comfortable enough to use for long periods.

Ironically, one of the main applications of full tang construction that seems most justified: large choppers or swords, is the one place I absolutely can't stand to use them. For a hard working chopper, the vibration is unbearable for long period with most examples. Yet inpact stress of chopping or batoning is the most demanding real world use on the tang construction from my experience. Try chopping down a tree with a machete some day however, see how long your hand lasts. Now consider doing that all day everyday. (Not the intended use of a Machete, which is built for light vegetation and thus the full tang is acceptible, I grew up swinging one in the jungles of central america, I only used the example to make a point.)

I personally believe that 99% of all knife failures are likely due to bad construction techniques, heat treating, stress risers, etc, and not due to being too thin, or not having enough tang. I have no basis for this belief, just a feeling, and the experience of breaking more than a few knives in the field. Every stick tang I've broken, have had noticible and obvious construction, design, or material (inclusion) flaws.

Sorry if that got rantish.. ;D

 

[Rick Marchand]

I think it comes down to a matter of perspective and experience. It also may come down to the way a maker designs their blades.

I addressed this in my original post. That is not what I am questioning here. It is when folks take it a step further and assert that there is no loss of strength in a less-than-full tang.

My guess is that any difference, if there at all, requires forces beyond what a human holding the knife can go trough.

My experience tells me different. Any knife can fail under "human power".



I guess the tang only has to be stronger/tougher than the blade itself, right?

 

[daizee]

I believe greater surface area per unit of mass generally translates into greater stiffness, which is why you can get greater strength from an I-beam (or H-beam, depending...) than from a solid bar of the same mass.

So by that reasoning, if correct, a fullered blade could be longer/wider than a similar blade of the same design without the fullering, while retaining the similar strength characteristics.

Waiting for beliefs to be challenged!

-Daizee

 

[javand]

I guess the tang only has to be stronger/tougher than the blade itself, right?

Right Rick, numerous tests have been done by abs smiths and others showing that properly constructed stick tang knives will break just about anywhere else before it'll break at the tang/ricasso union, which is the primarily failure point for hidden tang knives that do break.

Bear in mind of course, there are caveats to that construction. Heavy distal tapers, which were so traditionally prominent in classic contruction, are key in distributing and concentrating forces at the strongest portion of the blade. This is more analagous to your i-beam example. A surface ground flat volume of knife with a stick tang isn't going to be as strong to those tang breaking forces as a distal tapered distribution of the same volume by my understanding. However a thinner tip as someone previously mentioned, on the distally tapered piece might be more succeptible to lateral force breakage.

It gets back to the whole efficiency of form, and intended use.

 

[Remyrw]

Handle materials also have to play a role here. A stick tang embedded in a solid block of G10 or Micarta with at least 1/4" in each direction even up near the ricasso area will have a great deal of additional support. You're not relying on JUST that metal and you have moved much of your support further out to create a wider frame as well. On the other hand, to take it the opposite direction to an extreme, if you used a fragile wood and thinned things out to a very small cross section supporting that tang it is almost MORE likely to fail by damaging the wood under pressure while flexing.

Full tang construction when highly lightened probably has little to no additional lateral stability over a stick tang, but probably has significant improvements vertically. How much of a factor that is depends on the knife, how it's used and so on. On a small edc I can't see it mattering, but on a large chopper hacking away at something I can see that extra height being beneficial in theory. Properly anchored into the handle and guard a stick tang probably has significantly more strength than needed but may suffer from an increased likelihood of loosening the blade from the handle. If it's properly fit and the handle material isn't particularly fragile I don't see that as a big issue, particularly if it's bedded in with a good adhesive.

For the horizontal stability, I'm assuming the skeletonized tang didn't drill out too much right up by the ricasso, but has mostly focused on the area behind the front pin.

So, in short, I think that with a decent handle material you're adding strength to the base strength of the tang by enclosing it in a larger support structure. Provided the forces involved don't compromise that support structure you're in good shape. Full tangs gain some benefits if secured well, but are more dependent on the adhesive and any mechanical hold to bring that strength into play. In either case, I think it's more likely to see a failure elsewhere or due to poor production. A stick tang with a sharp corner to reduce in size right up at the ricasso area is creating a weak point at the worst possible spot. Add a guard and handle that are fitted to LOOK good but not really provide a lot of support and you have critically weakened the knife. On the other hand, a stick tang with a more gentle taper and well seated in the handle material, maybe even going all the way back to a butt cap... That can create an extremely strong and secure assembly.

 

[Rick Marchand]

I was trying not to have this thread become a justification for hidden/stick tangs. In my mind, there is no need because they are a design feature that when done properly, works. Just as poorly designed full tangs can fail.

I am not saying that full tangs make for better knives... that would be an asinine statement. But to say that a stick tang(of the same thickness and equal HT) can be constructed in a way that exhibits the same amount of lateral strength as a full tang, doesn't make sense to me.

 

[javand]

It doesn't to me either, I've definitely heard statements to that, but I think its more of "effectively just as strong".

As in; just as strong a knife in its entirety, not in terms of lateral breakage of the raw tangs themselves.

If the tangs are the strongest point of a knife of either design, its irrelevent, and becomes an issue of which design gives more value in terms beyond strength, since the weaker rest of the knife will fail first.

What's the point of having a tang 3 times as strong (and thick and heavy) as the rest of the knife, when the blade is the working end of the tool?

From a knifemakers perspective though, it doesn't pay usually to get to deep into the practical classifications of "what's strong enough", when its not likely to resonate in this SUV culture of bigger is always better. So you say to the guy asking you if your stick tang knife is going to break; "It's just as strong." And from a practical standpoint it probably is.

 

[Darrin Sanders]

When talking about unhandled blades, I think full tang would have to be stronger. But when you consider the strength you regain with a properly fitted guard, handle, & threaded buttcap, then I don't think you lose much if any strength with a hidden tang. When properly constructed, the blade of a knife should bend/break before the handle lets go, no matter what type of construction is used. One thing is for sure, if abused bad enough they will all fail. Just my .02.

 

[Salem Straub]

Handle materials also have to play a role here. A stick tang embedded in a solid block of G10 or Micarta with at least 1/4" in each direction even up near the ricasso area will have a great deal of additional support. You're not relying on JUST that metal and you have moved much of your support further out to create a wider frame as well. On the other hand, to take it the opposite direction to an extreme, if you used a fragile wood and thinned things out to a very small cross section supporting that tang it is almost MORE likely to fail by damaging the wood under pressure while flexing.

I think that Remy has a good point here. If such a knife is fitted with a tightly screwed down butt cap, and everything fits well, the handle block does add significant reinforcement to the tang. I could see how it could equal or exceed the HANDLE strength of the same knife with a full tang.

Apply strong lateral force to a handle with scales, the tang will bend, popping the scales off, or the scales will break and the tang will bend or snap. The scales are not really mechanically reinforced other than with bolts and epoxy. A good block handle would have to outright snap or the buttcap strip out before the tang would even start to bend. The tang is cased by metal at both ends, lateral force applied to the handle more or less is turned by leverage into lengthwise pulling force exerted on the tang and fittings.

Another thing to think about is what definition of strength to use- what if one defines it as the ability to bear up well over a long time in hard field conditions? A full tang knife has two big seams running the full perimeter of the handle. Even if a good epoxy seal is achieved, this is still an area where corrosion can creep into the joint. All sides of the tang are open to corrosion this way. Varying coefficients of thermal expansion can lead to material separation far more with a full tang knife than with a hidden tang design.

Old knives with full tangs often have badly corroded tangs and no original handle. Back then, a hidden tang design did a much better job of achieving a weather seal. Now we have good epoxies- but I've still seen handles separate that were glued up right. Another thing to look at is epoxy deterioration due to UV rays. Maybe not a huge issue, nonetheless one I've seen debated fairly hotly on BF.

Consider that a knife can unquestionably be constructed of more than adequate strength with hidden tang design, then add the above benefits and you have my argument why it's indeed possible for hidden to be superior overall.

That said, I do make more full tangs than hidden. Just design elements, you pick the right one for the job.

 

[AVigil]

In real world use Randall's have faired rather well all around the world in all climates with hidden tangs and leather handles. I understand people wanting to be ready for "Worse case scenario" but there is no knife that will fit that bill. Lots people around the world understand this and so have several knives for different tasks.