Question on hidden tang material

I

Iron&Light

Member
Hi Everyone,

I've got another question for the makers out there.

I have until this point made mainly full exposed tang knives. I want to start building a few hidden tang blades.

Do you recommend welding in a piece of mild steel rather than forge down the tang to a rod that passes through?

If so, what mild steel should I use? Can I just use cold rolled from HD? I have discovered that I know a little something about blade steels, but not nearly as much about other steels. Should the tang be left totally soft? Threads too? I had thought about case hardening the threads with Cherry Red, but not sure if it's necessary. Is distortion of threads from a quench a problem?

For convenience sake I'd rather just forge down the blade stock, though it will probably cost a little more than the mild steel in materials.

Can you guys expound a little on your experiences with the two techniques and the advantages of them?

Many thanks from a newbie,
 
I'd definitely forge the tang down. No question about it. I see absolutely zero advantage to welding a piece of mild steel onto a blade for a tang, even cost wise.

Your tang doesn't have to be round and it doesn't have to be hardened. Mine are usually widest (from top edge to bottom edge) right at the ricasso where the shoulders are cut for the guard and taper a little towards the butt end. So they're not round, more of a slightly tapered flat stick. My tangs are almost never hardened.
 
Without TIG welding with similar fill material, then annealing, its not a matter of IF a "welded on" tang joint is going to fail....its a matter of WHEN. I know there are plenty of people out there doing it.... especially with purchased damascus blades... their idea for doing it is "saving"....but its just a recepie for failure. Don't concern yourself with the "cost a little more"..... at the most, with the most exotic damascus, you MIGHT be using a few dollars worth to forge out the tang. With carbon steels its a few pennies. Saving yourself the grief of having a welded on tang fail, it worth FAR more then that. :)

As far as heat treated.....I tried that early on in my career, but learned quickly that it causes more issues then it solves. I actually can't remember the last time I heat treated the tang of a knife.

Think long and hard about what John said about the tang shape and size..... the type he described makes assembly much easier, and the shape/tapers lend strength to the tang.
 
Thank you gentlemen,

Welding in a tang seemed like a very risky proposition and I agree with your assessments. It is something you see a lot of though and many people try sell it as a good idea.

And it sounds like the threads are just fine without heat treatment. I was concerned they might not hold solidly without a bit of hardness.

I see the advantage of the flattened tang. Do you drill the handle with a bit as wide as the widest part of the tang and just epoxy it in, or, do you mortice it some way to a rectangular profile, or maybe you burn in on a smaller hole? I've burned on a tang or two and it fit nice and tight, but I wasn't sure it was worth the risk of getting the blade hot. I've got some heat block paste, but it still made me nervous.

In any case, I love definitive answers and I think I have one regarding the welded tang. Your thoughts are much appreciated,
 
I do the vast majority of my knives in the hidden tang format. Personally I use a long length bit (generally 1/4" X 6" long) I usually drill two holes, each at a slight angle so they intersect towards the end depth of the hole. I then use a broaching tool to clean out and square up the hole. Its always a good idea to have a little "slop" in that handle hole, the "glue" has to have at least a 1/16th" or so to get a secure "grip". I tried the "burning" thing early on, and found that in most exotic woods that causes the "bond" to be very weak.
 
I will give that double drilling mortice technique a shot. Maybe after I practice on a two by four so the holes converge.


Mr. Caffrey, I respect your years of experience and your MS rating. You said that most of your knives are hidden tang. There are obviously good reasons to do it, including the beauty of the full dimension of the handle material.


As I get a little older, I don't beat my knives like I used to and if I were lucky enough to own one of your blades I would no doubt take good care of it. However, back in the old days I used to chop wood and clear camp sites with my bowies. I always felt like a "bolt knife" relied too much on, well, the bolt and nut. I always chose an exposed tang or a cast rubbery handle. Obviously they weren't as pretty, but they were tough. Having said that, I never destroyed a bolt knife because I didn't use them for that.


Do you feel like the bolt knives are at a practical disadvantage regarding impact resistance or strength? Without hardened threads it seems like those might give under duress. Or is most of the work actually done by the epoxy? Would you still recommend a hidden tang for hard use knives? Do these ever break or stretch on you under reasonable use ( I know anything CAN be destroyed)?


While I don't see how anything could be stronger than a full exposed tang, that's not really my question. I just wanted to know if there is any practical danger in using the hidden tang technique on heavier knives. I'd bet that some of you have done some brutal testing of this.


As I move from knife user and collector to aspiring maker, I feel the need to chip away at some of the assumptions that are sold as truths to the knife consumer. I don't like marketing. I wanted to introduce this topic among people whose opinions were more grounded in experience. As a commercial photographer, I know all about marketing campaigns and who runs them. My focus is on the practical. Of course, it should still look awesome.


Thanks in advance to all who share their experience,
 
There's a lot more to it than just an unhardened tang. Besides, when it comes to steel, for the most part, hard means brittle. Softer steel is going to hold up to impact stresses better as far as not cracking or breaking. It would deform easier. Really the only thing on a knife that has to be super hard is the cutting edge.

A properly made hidden tang will be tough enough to handle anything you would ever do with a knife and also handle many things you shouldn't do with a knife. There have been more than a few hidden tang knives WITHOUT a bolted tang, meaning a single pin and epoxy, that have been torture tested to some extremes and have held up remarkably. They have done things and cut things that you should never do with any knife. Look around on the web, you can find reviews and videos plenty easy enough.

One last thing to consider......ANYTHING can be broken or destroyed. Never underestimate brute strength and stupidity.
 
"There's a lot more to it than just an unhardened tang. Besides, when it comes to steel, for the most part, hard means brittle. Softer steel is going to hold up to impact stresses better as far as not cracking or breaking. It would deform easier. Really the only thing on a knife that has to be super hard is the cutting edge."


I did not mean to imply that the threads should be edge hard, but I was wondering if spring hard would be useful. As you said, softer steel would deform easier. I can imagine the torque on those small strips of soft steel being pretty severe. I understand the trade off between hard and toughness, but maybe something at RC40 would be a better combination for that purpose. Believe me, I'm not trying to overcomplicate things, just wondering if it's necessary. Your handle is only going to be as strong as it's weakest point and it seems like it all comes down to that little nut and the threads inside. You sound pretty confident in the epoxy, but it seems to me that some materials might not stick that well, like an oily wood.

If I don't hear any horror stories about bolts popping off I'll dive in and make a few and see what I can do with them. I'm thinking about ten inch Bowies for clearing camp. I'm not trying to break them, but they would potentially see firewood chopping type impact.
 
I think you are overthinking it just a bit. Somewhere Karl Andersen, who is known for his takedown, hidden tang knives, has done some testing on that little bolt. Seems he hung a whole trailer load of cinder blocks from it, if I remember right.

When I said there's more to it, I meant that the threads don't take all of the shock and impact. In fact, they take very little. You have a guard that's fit tight against the blade shoulders, handle material that's fit tight to the back of the guard, and the nut pulling it all together. The fit between blade/guard and guard/handle and tang/handle/epoxy would be taking the majority of the forces. Only if you had a sloppy fit would the threads take most of the abuse.

And yes, I AM very confident in the epoxy (use certain types, tons of threads on that subject) but I'm equally confident, if not more so in the mechanical fastener of threaded tang/finial nut. I've built well over a hundred hidden tang knives assembled just like this and I'm pretty certain that there's not a significantly stronger way to build a knife.

Most bolts and screws that hold almost everything in our lives together are not hardened at all. You're over thinking it. But if you want to put a spring temper on your tang ends, by all means go for it. I'm certainly not trying to talk you out of it. Just answering your questions with references to other makers and a pretty fair amount of my own experience. :)
 
I agree with the others that you are overthinking it. Look at it this way, a very large percentage of swords throughout history were NOT full tang. This being a tool that many depended on with their lives in battle.
Here is a discussion on the topic I found on another forum if you are interested. It even briefly covers your welded tang. http://www.creativecargo.net/viewtopic.php?f=2&t=17172

Chris
 
I am prone to overthinking things. It can be a blessing or a curse. Attention to tiny details is what separates a good knife from a bad one. I imagine most of the forum members are detail oriented people. I'm not trying to make more work for myself on a invisible area, but looking for relevant improvements. It sounds like you guys are saying not to worry about the nut and threads. That's really what I'm looking for.

I hope that the other elements of my handles will be properly constructed and tight fitting. I currently use west systems 650 for epoxy and it seems pretty tough.

I forged up a Bowie last evening and made a tapered bar style tang about .25 inch thick. It's 1084 and I was going to make another out of 5160 if I get the chance tonight. It will take a few days to get them finished, but I'll put them together and give them what for on some trees I just cut down in my yard.

Chris, you touched on a big topic that covers a lot of people for a long time, but... The only full sized swords in the world that I am aware of that are not full tang are the Japanese style swords. As I understand it, that's because they were not really impact weapons, as the Japanese did not use metal armour, it was leather or bamboo. They are amazing blades, no doubt, but they could be much harder that their European counterparts because they never got smashed into armor, maybe another blade, but I think that was generally avoided too, they were not smashers. I have been to museums and armories in Istanbul, London, Toledo, Rome, Delhi and others and I can't remember any partial tangs, there are lots of hidden tangs, but not many partials. There are bound to be exceptions, of course, but I think the Japanese blades are actually the odd men out because of their unique usage. I certainly would not try to cut firewood with one of my katanas, but I'd give it a shot with a Celtic broadsword.

Thanks for your thoughts gentleman, I'm off to the shop for some testing.
 
I&L, I won't argue there are things you would do with certain blades and/or swords that you wouldn't with others. However, in your example of katana vs. broadsword, I think blade style and grind have a far greater impact on the decision than the style of handle. I posted that link because it did cover a broad topic and hoped it would help you with your decision.

I wish you the best of luck on the project and look forward to seeing the results.
Chris

PS as far as firewood goes, I'm partial to the "blades" on my Stihl! :biggrin:
 
I have, on occasion, used a welded extension on a tang. It was a proper blacksmith's lap-weld though, the extension was also high carbon steel, and thermal cycled afterwards to reduce the grain size....

The only full sized swords in the world that I am aware of that are not full tang are the Japanese style swords.
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Terminology alert!!!
I think what you call a full tang and what I call a full tang are two different things. There are hidden-tangs, through-tangs, and full-tangs. If the tang passes through the handle and is bolted or pienned on the end of the handle, it is a through-tang. If the tang is the full width and length of the handle it is a full-tang. If the tang is neither the full width or length of the handle but is entirely hidden by the handle, it is a hidden-tang. The vast majority of the swords ever made were through-tang construction, with hidden-tang swords used in Asia, and an occasional full-tang sword popping up here and there, mainly during the Bronze Age.
 
Hi George,

I think your terminology alert is a good point. I have been assuming that a full tang is anything that extends all the way to the pommel or butt. That would include full hidden(through) or full exposed where you can see its edge all the way around.

What you are calling hidden tang, I am calling partial tang, basically one that doesn't extend through the entire length. Like a katana. I guess I thought it could still be hidden, but go all the way through.

I think we agree entirely on the actual construction, but we are using different terms. I'm not sure if there is right or wrong, but I'd like to stop confusing people.

Did you weld in your tang because of problems with the simpler construction (like breakage), or just to try it? The big companies do it to save a little on materials, and I suppose, if it's done right, it can be an advantage to have tougher steel there. It would certainly make things more complicated and time consuming. I only want to try I if I have to, I have other fish to fry. The consensus ( and the answer I really wanted to hear) so far has been not to mess with it.

I am still a little nervous about the threads on that little nut though. I have been researching thread strength and have discovered a whole new world of boring details. There are as many nuts and bolts as there are applications and they are all different. The main useful info that I have gleaned so far is that for a typical 1/4 20 carbon steel nut that has been hardened and tempered, you want six threads in contact to get full strength. That boils down to about 130k psi, which is, I believe, very close to the rated strength of the 650 epoxy I am using, but there are lots fewer sq inches. Fewer threads and the strength drops rapidly. Corse threads are much stronger than fine. Typical nut has five threads within.

The variable are dizzying. How does this apply to a brass pommel nut, on steel, with ten threads and no hardening? Sigh...

I don't really want to know. I just want to be sure my, um, nuts don't go flying when I'm chopping on something.

I can't help it...I'm paranoid.
 
Yeah...honestly guy, you're being WAY too paranoid. There are countless WORLD CLASS makers that have made hundreds and thousands of HUGE bowies and camp knives that were held together with little finial nuts and have chopped all kinds of hard seasoned wood and deer and elk antler with no failures whatsoever. I know for a fact the vast majority of these are 10-24 or even smaller like 8-32.

I already mentioned that Karl Andersen has done testing on this because of these same paranoid questions from others and he hung a trailer load of cinder blocks from a 10-24 nut that was no more than 1/2" long. I'm sure you could look it up if you wanted to. It would probably be a lot more valuable than all the trivial little boring details of lab spec'd maximum thread strength/thread contact info since it's exactly related to your concerns.

I also told you that the nut is not the whole part of the equation but that seems to have gotten lost along the way.

Or you could do what most of the rest of us have done..........build one and test it yourself.

It raises little red flags with me when someone comes in, asks questions, gets lots replies form guys with first-hand experience and suggestions for topics to start a google search, then says he's reassured but comes right back later with the same paranoia and asking the same questions. He says he listened to the advice but you could see how actually it looks like the experienced guys that DID give advice just got ignored or looked over or their experience really didn't give a satisfactory answer or something.

Don't misunderstand me, you don't have to take my advice/experiences or any one else's either. And you certainly don't have to build knives the way I do. But a couple of us gave you real world first hand experience and it doesn't seem good enough for you. I guess it leaves me wondering why ask in the first place?

Bottom line......it's a knife. You're not going to be pulling a 52' semi trailer with it. You probably wouldn't believe how strong a little tiny 2-56 tapped hole is with only 1 or 2 threads engaged (yes I've actually done some real testing to satisfy my own curiosity) so I won't bother to mention it here.

I guess if I were you, I'd make one however you want and test it to see how it holds up doing what you want to do with it. Maybe that would satisfy your mind better. Best of luck to you.
 
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Look no farther than the construction of a Japanese sword. The handle was removable for cleaning which, as you can imagine, was a necessity. Blood and guts in your handle begin to stink in the noonday sun, and who likes a slimy grip? Not me. I don't mean to be overly simplistic or sound rude to anyone- but axes, machetes, cleavers, swords, and saws were invented because knives are the wrong tool for the job if the job requires beating on things to any degree.

I love watching survival shows, but I also think these shows give the impression that all knives are supposed to be sharpened crowbars. Hey, if I'm ever stranded on an island and need a knife that I can tie to a stick to kill a hog, then skin it, then make a shelter, and finally chop down trees to make a raft- I hope my knife is up to the job. But if I have to do all that with my knife I have zero expectations that there will be much left of the knife when I'm done. And that's okay! The knife will owe me nothing if I get out of there alive, even if the handle cracked or even fell off somewhere along the way.

I mean, honestly. Handles are for lazy chumps with girly hands, anyway. The blade is what matters. I would imagine that you can do anything Bear Grylls does even if your knife didn't have a handle because the stick tang broke off. You'd find a way. Aboriginals the world over have done these tasks with flint stones for ages. What we call "survival" a lot of the undeveloped world calls "Tuesday".
 
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The terminology is not set in stone, there are also stub tangs, half tangs, stick tangs etc... mostly describing the exact same thing.
Did you weld in your tang because of problems with the simpler construction (like breakage), or just to try it? The big companies do it to save a little on materials, and I suppose, if it's done right, it can be an advantage to have tougher steel there. It would certainly make things more complicated and time consuming. I only want to try I if I have to, I have other fish to fry. The consensus ( and the answer I really wanted to hear) so far has been not to mess with it.
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If you want to know about conserving materials look into medieval knives and their construction. The vast majority were made of the cheapest iron available with a little strip of hardenable steel welded on for the edge.
The few times I've done it, it was to conserve pattern-welded material, if I'd drawn a full length through tang out of it, it would not be as beefy a tang as I like so I simply added mass.

Or you could do what most of the rest of us have done..........build one and test it yourself.
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This is excellent advice. I started using hidden, stub tangs only after having tested a few to destruction. The weak links ended up being the handle material and epoxy prep, not the tang.
 
Thank you all for your thoughts,

I get the feeling I rubbed a few people the wrong way. I am a newcomer to the forum and I've only been making knives a few years. I have been mainly self taught and I have not seen any of the testing you are referring to. I also don't know who you are and unless there is an MS behind your name I really don't know what experience you have. Getting this kind of info is why I'm here and I appreciate the replies. These are honest questions and concerns I have about making a style of knife I've never made before. I'm looking for a small consensus of reasonable sounding answers, not a spitting contest. I think I got them.

I did make a few to test and I took your collective advice in all regards. I looked up nuts because it hadn't been discussed and it does seem like an important element. There are a lot of variables in construction options. As far as there being hundreds of world class makers using small thread nuts, well, that's exactly the kind of info I was looking for.

I'd consider the topic closed. Thanks for your help, especially Ed and George!
 
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