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Hammer Finish/No No


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Didn't Goddard say much the same thing in The Wonder of Knifemaking? I definitely recall the point about rounded tang joinings vs squared being in one of his two books.

I believe you are right. I remember hearing that argument before, and it was either in that book (the only knife making book I own) or on the internet.

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Sam, I'm a better grinder than forger, but thanks :)

 

Along with Tim Lively, Tai Goo and Ray Richards do a nice forging. But Don Fogg is the best I've seen.

 

 

I have not had the pleasure to see Don forge in person, but any of the hammer finish blades I have seen online have been top notch, a whole nother league. Tim Lively's forging is amasing, watching his video i was like "wow he's like a machine!". I like Ray's way of forging a convex, I am gonna have to try that sometime.

Edited by Sam Salvati

Let not the swords of good and free men be reforged into plowshares, but may they rest in a place of honor; ready, well oiled and God willing unused. For if the price of peace becomes licking the boots of tyrants, then "To Arms!" I say, and may the fortunes of war smile upon patriots

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Apparently I do have the issue, I picked up one here on my chair found Wayne's article and found the part mentioned. So I'll kinda paraphrase bits of it.

Basically the article starts out talking about the ricasso tang transition and the tang. About how he tapers it to make fitting the guard easier. Most failures having to do with defective tang or handle attachments. Then he starts listing out his rules he uses to make knives...

#1 make the tang as wide as you can without sacrificing strength of your handle material.

#2 Choose a strong handle material. Pay attention to grain orientation.

#3 Narrow tangs should be a spring temper, never same hardness as blade.

#4 for max strength silver braze all thread to tang end and use a threaded pommel.

#5 When glueing up use good epoxy and fill all air holes "When there are empty spaces in a handle, the elements can shift and that can lead to failure"

#6 Eliminate stress riser at ricasso/tang transition. During quenching lots of stress can lead to a crack in this area.

Blade should also be free of deep cracks.

Then it gets into the hammer finish area.

Basically says that some makers use a hammer finish to make it look old or primitive, but hammer marks aren't present on old or primitive knives, Each mark is a stress riser and can cause microscopic cracks during quench. Knives made from files and rasps can do the same because of the teeth left. some can have scale hammered into it which makes it an even better example of a stress riser. "When a blade fails because of a crack that started in the quench, there is usually a discolored area at the starting point of the break. The color indicates that the break started in the quench and there is usually a stress riser present."

 

Now he goes on to talk about one such experience at a demo at Fort Vancouver in Washington. A guy had brought a draw knife he'd forged out, that was heat treated, it had warped, he was going to do a soft-back temper using heat tongs and then straighten and when he did it snapped. Said the break crossed a medium size hammer mark that had scale hammered into it. "There was a dark line spreading out from the bottom of the dent; this is proof positive that the crack that caused the blade to break started in the quench. The break showed a nice, fine grain and such a blade usually will not fail when given a soft-back heat treatment."

 

He says the blade was hardened back first when placed in quench and that would put the back under compression and edge into tension. And says it's the reverse of what he thinks would give max strength in a blade.

 

 

=-=-=-=

 

I'm not really on board on the stress riser from hammer marks, mainly because with my hammers most of my marks are fairly rounded in all dimensions, so the mark in the steel itself is going to be rounded. In the article it did not say what the guy had made the draw knife from. So it's quite possible it may have been made from something that had a previous life. Could also have been quenched in something too harsh. *shrugs*

 

Now something I do wonder is on the ricasso to blade transition, It says to keep a nice radius to prevent cracks. Is this just in the quench? I've seen a lot of blades and done a couple now myself after seeing it done where a file guide is used after the blade is all hardened, to put a step all the way around the ricasso tang area. Which makes it a great deal easier to fit the guard. So since this is done after hardening, does that mean there's a little chance of a crack forming in this area? I would think the shoulders of the blade would kinda transfer most any force into the guard. Was just curious about that as I've seen a bunch doing that way and it seems like a good method, but can it cause problems? Way Wayne words it here, sounds like he's mainly concerned about it in a quench, which would kinda explain the lack of radius on katana and the like. As that area would probably be clayed up and experience little stress.

Edited by EdgarFigaro

Beau Erwin

www.ErwinKnives.com

Custom knives

Bcarta Composites

Stabilized Woods

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Thanks for the paraphrase, Beau.

 

Most of that is good, sound advice. Stress risers are real.

 

However, I have to absolutely, completely, and totally disagree with the statement that discoloration in the crack means it happened during the quench. Every blade I've ever seen broken in the quench was very clean in the break. If there is any discoloration, that has to mean the crack was already there.

 

It sounds like the way he's using the term "hammer finish" describes the look of when someone takes a ball-pein to a finished blade rather than an as-forged finish with a proper hammer.

 

IF that's the case, I can see where the dents and scale could cover a pre-existing crack, thus allowing a cracked blade to get quenched.

 

I see the whole thing as a case of misidentifying the time at which the crack started, that's all.

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About all that can be said about Wayne Goddard's article has already been said by people who know a lot more about the topic than I do, but I'd like to rise in defence of the knife rags. Many or most of the issues or like this last one where there is only one article that is worth reading but occasionally there is an article that is geared towards the knife maker rather the the buyer, or wannabee buyer. They are also my source of info on upcomming knife shows in time to put in for vacation time at work if I need it to attend. Without Blade, I would not have known that there are two shows next month that are within reasonable driving distance of me. I do have to agree that there is too much eye candy featured. Most of the knives pictured are lookers, not users. Let's face it precious few carved, engraved, enameled pocket knives with gold MOP scales or going to be carried in anyone's pocket and just as few mosaic damascus skinner are going to take the hide off of any dead critter but they are nice to look at.

 

Doug Lester

HELP...I'm a twenty year old trapped in the body of an old man!!!

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stress risers are potentialy all over the place ,a rounded hammer mark? compared to a ricasso/blade boundry or filework or how about a choil or makers stamp?

Make it as you like it .

the only thing I have against hammer marked blades is they are often too thick to cut well .

forging soul in to steel

 

owenbush.co.uk

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stress risers are potentialy all over the place ,a rounded hammer mark? compared to a ricasso/blade boundry or filework or how about a choil or makers stamp?

Make it as you like it .

the only thing I have against hammer marked blades is they are often too thick to cut well .

 

 

I get some suggestions that my work isn't REAL hammer finish work due to the somewhat wide polished edge bevel I put on my hammer finish blades, but you can only forge down so much before you run the risk of losing all the carbon from the edge and end up haveing to file/grind up into steeper geometry anyway, so i forge down then with the grinder bring that edge angle down enough so they are effective cutters not just choppers.

Let not the swords of good and free men be reforged into plowshares, but may they rest in a place of honor; ready, well oiled and God willing unused. For if the price of peace becomes licking the boots of tyrants, then "To Arms!" I say, and may the fortunes of war smile upon patriots

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Now he goes on to talk about one such experience at a demo at Fort Vancouver in Washington. A guy had brought a draw knife he'd forged out, that was heat treated, it had warped, he was going to do a soft-back temper using heat tongs and then straighten and when he did it snapped. Said the break crossed a medium size hammer mark that had scale hammered into it. "There was a dark line spreading out from the bottom of the dent; this is proof positive that the crack that caused the blade to break started in the quench. The break showed a nice, fine grain and such a blade usually will not fail when given a soft-back heat treatment."

 

He says the blade was hardened back first when placed in quench and that would put the back under compression and edge into tension. And says it's the reverse of what he thinks would give max strength in a blade.

 

I knew I'd heard this argument before. The Wonder of Knifemaking, page 58.

MacGyver is my patron saint.

 

"There's nothing in the universe cold steel won't cut." -Conan of Cimmeria-

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Edited by Robert Kobayashi
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All of nature seeks equilibrium, Robert. :)

 

Mostly the reasons things crack in the quench are, well.... there are are many potential reasons. Any sudden change in the section thickness of a part that will be heated to above critical and quenched in 'anything', has the potential to crack at the section thickness change. The easier the material hardens, the less critical this is. Hence we have air-hardening die steels. The outside corners are not nearly so likely to fall of when you harden them, if it will harden in air, rather than need to be water quenched to get hard. I have had blades fail along a grinder scratch. I have seen pattern welded blades fail (i.e. crack in the quench) where I hit it too hard once with the power hammer in the middle early in forging, and left sharp steps in the pattern. I had only a moderate amount of difficulty fixing the section geometry to match with the rest of the blade, so when the forging was done, the surface did not betray the mistake. However the sudden shift in the pattern at that spot, is/was, I believe, what caused it to fail. I have hardened and tempered a lot of blades. My own, and for some years, other people's as well. The lower the hardenability of the steel, and the more drastic the quench has to be, the more prone to trouble with cracks things are, relative also to the manganese content of the steel (and crud). Fabulous for making hamon, more risk in hardening. Part loss, need for skilled operators, and the need for ever more complex die shapes are what led us to air hardening alloys.

 

Over-heating can cause cracking in the quench. Uneven grinding. Bad welds, or less than perfect welds in some mixes of materials in pattern welded steel. Using the wrong quenchant for the steel you have. The list can go on and on...

 

I'll give you my most infamous comment, for the last few years anyway. "It depends" :D

 

Oh, and I forgot one really important one. If there are significant changes in the microstructure, prior to the final heat to austenitize before quenching, this too can cause troubles. Not necessarily cracking, though that could be, but warping and twisting are more likely. The better you do the set-up before the final heat treatment, the better your chances of success in the end. For me that means a minimum of three thermal cycles, heated above critical and air cooled, in most cases. Often many more than three.

Edited by Howard Clark
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[1

Edited by Robert Kobayashi
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  • 11 months later...

I pick up Blade magazine sometimes, and even bought the big Blade Book 09 for $27. I think they are OK for pictures. I like to see people's finish work. I find that all of these publications are full of editing mistakes and are usually not worth reading. It's nice to have a lot of pictures, but they do influence style just by being around. I agree with Howard, most of the time reading them leaves me LESS inspired and sometimes angry.

I think this forum itself is The Best resource for bladesmiths, better than any magazine. This is a giant persistent conversation that you can jump into any time. And it has all the pretty pictures as well.

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In defense of Blade Magazine......I've been reading and subscribing to it since 1973..American Blade back then....I find it hard to live and create in a void...I find of course much BS in there but mixed in are great pictures and articles constantly giving me new ideas to work with and goals to try to accomplish,,,,I just finished a damascus hatchet following Tim Poiters directions from the last issue ...I also see work created by people I've met over the years and can watch their progress...many times I meet a smith I haven't met before yet I know their work from Blade...It also keeps me up to date on shows,trends and new ideas.......and the big plus is it's great bathroom reading..

"Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did do. So throw off the bowlines. Sail away from the safe harbor. Catch the trade winds in your sails. Explore. Dream. Discover." — Mark Twain

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My motto regarding magazines, forums, books, strangers I meet on the street, etc. is this: Accept all sources of knowledge. They will all have a ratio of BS to good information. The trick is building your own internal filter so you can sort the wheat from the chaff.

 

For example: This month's Blade magazine has an excellent article on building a salt bath for heat treating. True, these sorts of useful (from a bladesmith's perspective) articles are rare in commercial rags, but don't give up on oysters because every one doesn't have a pearl in it!

 

Cheers,

 

--Dave

-----------------------------------------------

"It is not the critic who counts; not the man who points out how the strong man stumbles, or where the doer of deeds could have done them better. The credit belongs to the man who is actually in the arena, whose face is marred by dust and sweat and blood, who strives valiantly; who errs and comes short again and again; because there is not effort without error and shortcomings; but who does actually strive to do the deed; who knows the great enthusiasm, the great devotion, who spends himself in a worthy cause, who at the best knows in the end the triumph of high achievement and who at the worst, if he fails, at least he fails while daring greatly." -- Theodore Roosevelt

http://stephensforge.com

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