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OKC knives bend
- Thread starter dingy
- Start date
All,
The knives in question are not bad.
I will offer an explanation as to why the tangs are/will bend.
All of the pictured knives are made from carbon steel. Ontario uses a salt pot to harden all of it's carbon steel blades. The blades are racked and placed in the salt bath. The depth of the blades in the salt varies depending on the length. The salt usually covers the blade and the tang/blade shoulder. The remainder of the tang is not immersed in the salt so it will not get to Austenizing (hardening) temperature and will not fully harden during the quench. So the end of the tang gets progressively softer toward the pommel end. Differential hardening is the technical term.
Our (and the military) philosophy is that it is better to have a soft tang (that can be re-bent to straightness) than a hardened tang that is broken making a useless knife.
All of the carbon knife makers who use a salt bath for hardening will have this situation unless the entire blade/tang is fully immersed. (Then there will be other issues.)
I hope this answers your questions.
Best Regards,
Paul Tsujimoto
V.P. of Engineering
Ontario Knife Company
The knives in question are not bad.
I will offer an explanation as to why the tangs are/will bend.
All of the pictured knives are made from carbon steel. Ontario uses a salt pot to harden all of it's carbon steel blades. The blades are racked and placed in the salt bath. The depth of the blades in the salt varies depending on the length. The salt usually covers the blade and the tang/blade shoulder. The remainder of the tang is not immersed in the salt so it will not get to Austenizing (hardening) temperature and will not fully harden during the quench. So the end of the tang gets progressively softer toward the pommel end. Differential hardening is the technical term.
Our (and the military) philosophy is that it is better to have a soft tang (that can be re-bent to straightness) than a hardened tang that is broken making a useless knife.
All of the carbon knife makers who use a salt bath for hardening will have this situation unless the entire blade/tang is fully immersed. (Then there will be other issues.)
I hope this answers your questions.
Best Regards,
Paul Tsujimoto
V.P. of Engineering
Ontario Knife Company
very cool .
thanks for letting me know how your knives have been made and the company cares about buyers.
other Qs :
1. i can not bend thicker tangs on sp10&sp5 , but i felt there are flex when applying my full arm force. it is the sign that thicker SP knives were fully hardened ?
2.the machetes acts like spring ,when i did the bending game. are machetes fully hardened?
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Dingy,
1) The SP blades you mentioned are all 0.250" thick which means you will need more force to bend. They are hardened same as the 0.1875" thick SP models. The salt line ends just before the processing hole.
2) The machete tangs are full tang so there is more cross sectional material resisting the bend. IIRC, the salt line comes to around mid tang for the machetes.
Hope this helps.
Best Regards,
Paul Tsujimoto
V.P. of Engineering
Ontario Knife Company
1) The SP blades you mentioned are all 0.250" thick which means you will need more force to bend. They are hardened same as the 0.1875" thick SP models. The salt line ends just before the processing hole.
2) The machete tangs are full tang so there is more cross sectional material resisting the bend. IIRC, the salt line comes to around mid tang for the machetes.
Hope this helps.
Best Regards,
Paul Tsujimoto
V.P. of Engineering
Ontario Knife Company
Also I would add that when you try to bend a long knife with bare hands, you're putting pressure on the blade itself. When you're trying to bend a small knife, the pressure will tend to concentrate at the blade/tang junction. Thus, the different results.
Tooj:
Thanks for that information and explanation. Explaining the reason and why surely will give people more information on how to better handle their knives.
From my understanding hardened steel breaking is not a good thing at moment of breaking. So this way would seem to be also a safer way for knives being used very hard. This is being my pseudo intellectuals delusion...er conjecture.
May the Donuts Force be with you! (With Coffee!)
Thanks again for you and your coworkers telling the public honestly about your products and industry processes and practices for an end result and such it is very enlightening. Its one of the reason most of my knives are Ontarios, besides the great quality at a great price that lets me have several at the cost of a similar product that has the same steel and such.
The one known Roguer. (here that is)
Thanks for that information and explanation. Explaining the reason and why surely will give people more information on how to better handle their knives.
From my understanding hardened steel breaking is not a good thing at moment of breaking. So this way would seem to be also a safer way for knives being used very hard. This is being my pseudo intellectuals delusion...er conjecture.
May the Donuts Force be with you! (With Coffee!)
Thanks again for you and your coworkers telling the public honestly about your products and industry processes and practices for an end result and such it is very enlightening. Its one of the reason most of my knives are Ontarios, besides the great quality at a great price that lets me have several at the cost of a similar product that has the same steel and such.
The one known Roguer. (here that is)
OntarioKnifeCompany
Moderator
- Joined
- Jan 3, 2013
- Messages
- 403
This is a great thread, and there's not really much to add at this point. Thanks for jumping in here, Tooj. One of the things that always stands out to me is the fact that "hard" doesn't always mean "good." Unrelated to this, Tooj pointed out to me less than an hour ago that glass is much harder than blade steel. I wouldn't want a knife made from it though.
Only thing I would add is that bending knives is always dangerous. If you bend a knife so that your hands are moving down and the middle of the knife is bending upward towards your face, that's even worse. The blade of an improperly heat-treated, cheaply made knife could shatter and steel fragments can hit your eyes. I hope he was at least wearing safety goggles when he was doing that.
- Joined
- Oct 3, 2007
- Messages
- 987
Bill Bagwell differentially heat treats 4 different sections of his blades but leaves the tang "dead soft". The relevant part is at 9:00:
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i get it .
from my very restricted and narrow exprience that knife breaking mostly occurred at transition of tang and blade ,so leaving a soft tail does it really help ?
If the blade was fully hardened , and is it prone to get break , or damage at the tang tail ?
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i wearing goggles when doing that. but no Jason Voorhees mask
Dingy,
When the blade is hardened in the salt pot, the blade is fully immersed vertically and receives the full amount of heat, the tang is held out of the salt and doesn't get the full heat of the pot. What we want, after the blade is quenched, is for the blade area to be at full hardness, the blade/tang shoulder at spring hardness and the hardness to decrease as it goes toward the pommel end of the tang. Somewhere in the middle of the tang, the hardness is basically soft. The Blade/Tang shoulder is probably the most critical area in regards to breakage so we want that area semi hard AND strong. It is at what we call spring hardness. All of this is determined by how far we immerse the blade into the pot and is accomplished through trial and error. Once we get the proper distance it becomes the spec. Each blade is different.
If we hardened the entire tang, there would be warpage that we would not be able to remove from the tang and your knife would most likely be bent and you would not be able to straighten it. A soft tang allows us to tweek the tang for straightness. Also a hardened tang could break, rendering the knife useless.
I hope all of this helps.
All,
Thanks for being loyal customers and good Blade Forumites.
Best Regards,
Paul Tsujimoto
V.P. of Engineering
Ontario Knife Company
- Joined
- May 9, 2002
- Messages
- 12,622
I have come to appreciate a softer tang when it comes to thinner stock knives (please keep in mind, I'm a khukuri guy. Anything under 3/8" at the spine is "thin" to me
). I would much rather bend my knife if I overloaded it rather than break it.
Stupid teenager confession:
Back in 1998 when I was 17, I bought a Ka-Bar USMC from a local army surplus shop. I think it cost around $40 back then, and I bought it because I wanted to step up from my flea-market Colt knives (made in Taiwan at the time, I think). The Ka-Bar was much nicer finished, much better edge, and filled me with confidence with its superb build quality in comparison to the Colt bowie.
The Ka-Bar was great. It cut and prodded and was a fantastic knife. I took it on a camping trip with my girlfriend and decided to kill some time chucking it at a log. I stuck it a few times, then messed up a throw and knife hit the hard stump broadside with sickening WHACK. Sure enough, the knife was bent about 10 degrees in the middle of the handle. Disgusted, I bent it back between a tree branch, sheathed it, and pouted. I grabbed my Colt from my pack and tried to bend it...nothin'. I felt cheated that this icon of cutlery had failed where the $15 flea market butter knife had survived.
I tossed the Colt a bit more. I never missed. On my last throw the satisfying THUNK was more of a POOUNT with the sound of something hitting the ground there after. Right at the junction where my Ka-Bar had bent, the Colt was buried in the stump snapped in half. I reluctantly decided that I would continue to use the Ka-Bar and that my throwing time was over.
You know what, in the last 20 years, I have used both that old Ka-Bar and a number of OKC knives with similar construction, and I have never once bent them using and borderline abusing them. I'm not saying that giving them a good torque to test them is a bad thing, but the knives in question seem to have performed to their design specifications.
). I would much rather bend my knife if I overloaded it rather than break it.Stupid teenager confession:
Back in 1998 when I was 17, I bought a Ka-Bar USMC from a local army surplus shop. I think it cost around $40 back then, and I bought it because I wanted to step up from my flea-market Colt knives (made in Taiwan at the time, I think). The Ka-Bar was much nicer finished, much better edge, and filled me with confidence with its superb build quality in comparison to the Colt bowie.
The Ka-Bar was great. It cut and prodded and was a fantastic knife. I took it on a camping trip with my girlfriend and decided to kill some time chucking it at a log. I stuck it a few times, then messed up a throw and knife hit the hard stump broadside with sickening WHACK. Sure enough, the knife was bent about 10 degrees in the middle of the handle. Disgusted, I bent it back between a tree branch, sheathed it, and pouted. I grabbed my Colt from my pack and tried to bend it...nothin'. I felt cheated that this icon of cutlery had failed where the $15 flea market butter knife had survived.
I tossed the Colt a bit more. I never missed. On my last throw the satisfying THUNK was more of a POOUNT with the sound of something hitting the ground there after. Right at the junction where my Ka-Bar had bent, the Colt was buried in the stump snapped in half. I reluctantly decided that I would continue to use the Ka-Bar and that my throwing time was over.
You know what, in the last 20 years, I have used both that old Ka-Bar and a number of OKC knives with similar construction, and I have never once bent them using and borderline abusing them. I'm not saying that giving them a good torque to test them is a bad thing, but the knives in question seem to have performed to their design specifications.
Toooj
last night i stripped my sp5 that removed off rubber handle some days before, and use sand paper 1500,2500,3000&5000 items to polish the tang of my stripped sp5 , and there is no queching line on the tang.
there should be a visable line . right? if the tang was differently quenched.
then i use a knife to do push cut on the tang with a controlled way , what i found is that the knife can not cut off crumbs from the tang , i think THIS sp5 is Unanimously hardened.
that is some how alittle bit contradicted with what you told me above.
anyway , thank you.
last night i stripped my sp5 that removed off rubber handle some days before, and use sand paper 1500,2500,3000&5000 items to polish the tang of my stripped sp5 , and there is no queching line on the tang.
there should be a visable line . right? if the tang was differently quenched.
then i use a knife to do push cut on the tang with a controlled way , what i found is that the knife can not cut off crumbs from the tang , i think THIS sp5 is Unanimously hardened.
that is some how alittle bit contradicted with what you told me above.
anyway , thank you.
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Hi you all and Toooj.
I bend my ff6，and there is no flex as expected.
What you have been told my are:
"The Blade/Tang shoulder is probably the most critical area in regards to breakage so we want that area semi hard AND strong. It is at what we call spring hardness. "
but my two 499s and ff6 are easily bending at The Blade/Tang shoulder , and this area is not strong and never spring back.
and you told me that "The knives in question are not bad."&" Each blade is different".
is my understanding right ?
I bend my ff6，and there is no flex as expected.
What you have been told my are:
"The Blade/Tang shoulder is probably the most critical area in regards to breakage so we want that area semi hard AND strong. It is at what we call spring hardness. "
but my two 499s and ff6 are easily bending at The Blade/Tang shoulder , and this area is not strong and never spring back.
and you told me that "The knives in question are not bad."&" Each blade is different".
is my understanding right ?
No disrespect intended, but given all the info available in the form of reviews and videos, and even the company vp of engineering who is good enough to comment on these things... I fail to see the point in working hard trying to bend a perfectly good knife.
I mean my car reportedly has airbags that will go off in the case of a front end collision... I think I'll take the manufacturers word on that one.
I mean my car reportedly has airbags that will go off in the case of a front end collision... I think I'll take the manufacturers word on that one.
