Full tang VS narrow tang?

SShepherd said:
useing a knife as a prybar is a bit retarded anyway..IMO

abuse any knife, and theres no telling where it's going to break.
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Good point :)

And also another good point by Bill. I'm pretty sure nobody is breaking a knife at the tang unless they're REALLY TRYING to break it. Like with a 5' cheater pipe, or a hammer... or a ninja. Or three ninjas.
 
Hahah... ok, so we've established that under any normal circumstances a narrow or full tang knife can't be broken but, the point of this thread was what if it's taken further.. what if 3 ninjas are using full force.. which tang will break first?
 
Well, I for one would have said fulltang is stronger a couple weeks ago and never have made my JS test knife a stick tang. But, after visiting with Nick at his shop and seeing his JS test knife and talking with him, I am not so sure. I can see the simple advantage of the full tang simply having more material and less drastic line changes. But, his test knife was a beautiful sick tang and was still dead straight in the guard/handle area and had a small flowing curve in the area about a 1/3 from the tip. Then he went on with a discussion about the plunges. His are very crisp and go very very close to the spine. He then stated that he had tested to destruction something like 26 or 28 blades of this type construction and not one had broke at the plunges or the tang. Having got to know him a bit, I believe him and bet these test knives were all very well made and finished. If nothing else I truly admire the effort, dedication and sacrifice he made to seek the answers to his own satisfaction. One thing I did pick up on was that he hardens his blades then files the guard/tang shoulders after HT, by heat sinking the blade and heating the guard/tang to a blue heat. This will soften the area a bit and change its elastic limit with no loss to the blades edge. I still suspect the full tang may be slightly stronger, but, that it is a such mute point on a well crafted knife. About the only way it would probably make any difference would be it you spanned a 12 inch knife over a 8" opening and stood on it and bounced your weight up and down. Then, it might break at the guard tang area, only proving, without a doubt, that anyone who did such a thing was an total idiot. In other words I now think that the choice of full tang or stick is a choice of design and function, rather than strength. It is like a lot of other things that are accepted as fact, like forged vs stock removal, once you really look into them and study the actual results and what is behind these results, one should not just accept things just because everyone says so. I was at a blacksmith hammer in last summer with a couple lectures on knife making and was amazed at the number of experienced people who still thought that a magnet was the way to check for quench temperature. So had I until I really began to learn. It is a simple trap we all fall into, time and again. I hope I am learning to avoid it so often. Jim
 
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The question really shouldn't be whether one or the other is stronger, merely whether or not one works with the given knife design well or not.
For any reasonable knife use, the differences are negligible, if not nonexistent.
The right way to get an answer would never be to discuss anecdotal answers from questionably informed participants - industry has addressed these things a thousand times over. Ask an engineer! Otherwise, if we're willing to forgo the vast resources available to us through the work of others, we might as well stop having these conversations and go back to the mentality of "Well, it worked for my Pappy, so it's good enough for me!"

I, for one, know my Pappy would slap the poop out of me for not taking advantage of understanding and technology for the sake of ignorance!
 
ib2v4u said:
About the only way it would probably make any difference would be it you spanned a 12 inch knife over a 8" opening and stood on it and bounced your weight up and down. Then, it might break at the guard tang area, only proving, without a doubt, that anyone who did such a thing was a total idiot. In other words I now think that the choice of full tang or stick is a choice of design and function, rather than strength. It
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What you said, Jim. :)
 
I have done some testing on this subject and will give you my conclusion at the end...
EIther way,forged or stock removal to identical 3/16 in thick blade,one having a stick tang and the other a full tang.Grind and differentialy heat treat as normal.Clamp in vise at the riccasso area and bend the tangs.Narrow tang will have a little less resistance to the bend than the full tang due to the full tang has wider steel and thus tougher to bend,both should not break only bend...Now straighten those same tangs out and normalize the blades then do a full all the way to the end of the tang heat treat.Clamp in the vise the same as before,now bend them,They will break just like the blade would if bent with this type HT.Where they break only the steel knows and it will tell you where and when...

If you take 2 pieces of mild steel and cut grooves in it and bend it,then it still bends not breaks thus is the case with a annealed or normalized or spring tempered tang.Make the mild steel the width of the stick tang and the full tang then bend,the only difference between the 2 is the resistance to the bend from more width of steel in one knife.Try it with a spring tempered set of tangs,then hardened ones...
If the blade is differentially heat treated and from the riccasso back is soft both styles of knife are strong,The full tang might pop a scale,but it will still work as a knife,the full tang might bust through the handle material,but it is still a knife. If the whole knife is at full heat treat,you run the risk of it breaking anywhere in the knife,the handle should give enough strength to the tang to keep it straight enough that the blade breaks,but it may not.As for stress risers filework down the spine is one of the biggest stress risers you can have,but on a differentially heat treated blade they dont pose a problem like they do on fully heat treated blades....

So in my opinion it isnt stick versus full tang,as both are strong, but how it is heat treated....

Sorry to ramble,and as always this is just my 2 cents worth.
Bruce
 
I will point out, for those of you who are interested:

In a beam, when the width doubles, the resistance to deformation doubles. (duh)

In a beam, when the thickness doubles, the resistance to deformation increases by a factor of eight. (Wow)

In simple terms, when you bend something, the outside of the bend stretches, the inside is in compression, and somewhere around the middle is a neutral plane where the material is not in compression or tension and is contributing almost nothing to the structure. This is why a hollow axle is almost as stiff as a solid axle (and has much better strength to weight ratio as a result). So, to put in layman's terms, the more stuff you have, the farther away from that neutral axis (the greater your moment of inertia) the stiffer your beam will be.

So, given two tubes of the same material and weight and length, but different wall thickness and diameter, the 2" diameter thin wall tube will be stiffer and stronger than the 1" diameter thick wall tube, because the thin wall tube is a larger diameter and has a greater sectional modulus. Same amount of material, just in a different shape. This works great until you get to buckling failures.

Making something hollow does not make it stiffer, it increases its strength to weight ratio, but the solid (of the same OD) is still stiffer and stronger.

Cutting flutes into a rifle barrel does not make it stiffer. But two barrels of the same weight, one regular, the other a fat bull barrel with weight reducing flutes, the fat one will be stiffer.

A thin full tang will be strong in one direction and weak in the other. A thicker, but narrower stick tang would be stronger than a thin full tang in one direction, and weaker in the other. So which is stronger would be a function of the dimensions of the tangs and the direction of the loads.

I hope this made sense.
 
I think a lot of this really came about when stainless steels first started to get popular. Makers used to differentially treated carbon steel tried to use fully hardened stainless in the same design and found that fully hard narrow tangs were not as strong as what they were used to.

You can't really consider any one factor individually. You have to look at the whole knife as a package. Steel, HT, handle material, design, intended use, they all need to be factored together.

Most of the guys I hear saying that are using fully hardened stainless steels.
 
Jason, I suspect you're right. I think it's one of those apples/oranges things that started out innocently enough and is now a myth that "everyone knows."

Thanks to Bruce and Nathan for shining some light on the subject for us :)
 
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