Awesome to learn this, never seen this method before. But make sure you wear eye protection doing this with those chips breaking off! My father lost vision in one of his eyes from a small piece of metal embedded in it.
@@Creelyblades The science bro: Plastic deformation and thermal deformation ;) (Forget that, didn't watch the rest!) You're a cool ass guy btw. First time I actually saw a video of you. EDIT: Totally lied and didnt watch lmao! Okay NO thermal deformation but.. plastic deformation by exceeding transverse yield strength? Maybe? Ha
I don't on the science side of things understand the difference between doing it warp down or warp up besides your hand is dampening some of the force so less amount of energy dispersed per hit?
I have an old machete that was my paps in WW2 im trying to get refurbished(straight and sharpened...MAYBE a custom wooden handel like a soldier would have done while in the field). U know anyone who can do this or at least get it straight. There's also slight damage(additional more sever bending)on the blade i think is contributing to the warp
Hi Gary, I think i can shed a little insight into what is happening to fix the warp. You mention that the carbide hammer leaves some very small divots, which means that when you strike the surface of the steel, you are locally creating stresses beyond the yield strength and flowing material away from the point of impact. This is why the steel chips if you strike too closely to an edge: there is no support steel in the cutouts to limit the yield and the steel is displaced beyond the breaking strain. Here is the explanation of the (un)intuitiveness of this repair: Like you said in the video, most folks would think to put warp-side down, where the center is bowed up, and then strike the bowed-up center to flatten the piece. This strategy assumes that the warp can be corrected by 3-point bending beyond the yield strength of the blade to induce a new warp to cancel out the existing warp. One can think of a downward bending moment on a blade (or a beam) as creating strain that varies from positive (stretch) to negative (compression) from the bottom surface to top surface, respectively. With a hammer blow on a flat surface, you will never be able to fully flatten a warped blade because you can only have get the blade to temporarily flatten during impact, but the elastic response of the steel will cause it to rebound. When you put the warp side up, where the blade is curving upwards, the bend in the blade can be thought of as the top surface of the blade being too short relative to the bottom surface. This variation of "too short" to "too long" across the thickness of the blade is the bending moment we need to relax out of the blade. By striking the top surface of the blade with the hard ceramic ball, you are locally yielding the blade and causing steel to flow outward from the point of impact; namely, you are causing the steel at the surface of the blade to stretch out and away from the point of impact. Since the blade has been placed warp-side up, which is the "too short" side, by hammering around on this surface we are stretching it out, thereby removing the bend. I cannot say whether the localized residual stresses that the hammering creates is "relaxing" out the residual stresses from the heat treat that caused the warp in the first place, or whether there is ample residual stress from the heat treat that is in a push-pull balance with the residual stresses from the hammer blows. I guess you will find out when you have the blades ground to their final thicknesses whether the heat-treat warping stresses permeate throughout the thickness of the blade while the hammer blow stresses are just at the surface. If that is the case then you might find the blades start to warp again when the surfaces are ground. Looking forward to these makos. I'll be taking one with me on a boundary waters canoe trip this summer if they are ready by then.
You are correct there sir *I think*. Just don't ask me to make one. I've had 2 people try and fuck Gary over cause I'm in a non-profit hobby deal. It's incredibly fucked up to even ask. :| Albeit I doubt he would care about 2 knives, it's the principle.
You should easily be able to do it with a regular ballpeen hammer as it's going to well exceed the transverse yield strength of knife steels? I don't think hardness matters, energy/force does. **JUST A GUESS** *not a professional*
As you know Murray Carter also had made a limited run of Tagane hammers. Murray's hammer only had one carbide on the end and he was selling them for $250. Look up "Trow and Holden Carbide Mill Pick" . You could take this hammer by Trow and Holden and shape/grind either end of the hammer heads to your liking. It's only $167 for two ends that could be just like the ones Murray made up, but just a longer head. You could make one having one end just like the one Murray made which is somewhat sharp, and the other more rounded off as to not leave the marking on the blade like Murray's. The "wedge" shape allows more precise control of your desired bend.
I found that keeping all my blades clamped together from the quench to the last temper cycle really helps with the warping. Works really good with thicker shorter knives, kitchen knives are a different story
Do you have those water jetted? Apparently grinding at lower rpm and or under water can help reduce some stress. The less stress you put the steel in pre heat treat the less they will warp as bad. Does Peter's offer a stress relief cycle? I've also heard of Vibratory Stress Relief.
I had a similar concern whether it caused any damage to the steel. I actually ran it by the designer of the steel only to learn that he endorsed the method. I am pretty confident that it is not creating those issues, the biggest issue is grinding out the divits, but in the case of my usage that’s no problem.
@@Creelyblades Very interesting and could be a game changer! So I assume these are the Magnacut Mako's then, and Larrin reckons this would be just fine?
@@burtjoubert yes, Most of the Magnacut makos are at the grinder, but I had about 55 warped ones that I had to hold back. I lost about three of them that I just could not get straight, but otherwise now I have reclaimed 53.
@@Creelyblades Wow, it's very curious that so many Magnacut heat treats warp. Any ideas why? Could it be Magnacut itself, or just the heat treat guys getting used to it?
Anybody know if this work with a regular ball peen? I have a massive warp on an 11” blade I’m working on. I havent tempered so I’m going to try the trick of putting the blade on a piece of angle and tempering maybe this will work to get wtvr warp is left out?
Straighting in the temper is a better first choice, but it does not aways work, or it is not perfectly straight. A regular ball pean hammer will not work. Also you would not do this until after the temper cycles.
@Maciej_Jan_Dlugosz if you were straightening a kitchen knife that was already hardened, and bent in the process of use. It was simply the mechanism of bending it back using the ball peen hammer. This technique is something entirely different.
Good morning from the UK, Really looking forward to delivery of my Folklore (Classic Bushcraft) - CPM Magnacut 👍👍
Mee too, Folklore #774, you? :D
Thank you, great tip and thanks for sharing
Awesome to learn this, never seen this method before. But make sure you wear eye protection doing this with those chips breaking off! My father lost vision in one of his eyes from a small piece of metal embedded in it.
And gloves, I got a chip lodged in my knuckle
@@Creelyblades The science bro: Plastic deformation and thermal deformation ;) (Forget that, didn't watch the rest!) You're a cool ass guy btw. First time I actually saw a video of you. EDIT: Totally lied and didnt watch lmao! Okay NO thermal deformation but.. plastic deformation by exceeding transverse yield strength? Maybe? Ha
I don't on the science side of things understand the difference between doing it warp down or warp up besides your hand is dampening some of the force so less amount of energy dispersed per hit?
I thought of using a set of pliers to clamp down on it after heating it up
In japan traditional bladesmiths straighten the blades exactly like this with a small carbide tipt hammer
This is very cool.. thanks!
Excited to try that today.
Always done the tempering method what's a counterbalance. But it doesn't work as well with stainless
I have an old machete that was my paps in WW2 im trying to get refurbished(straight and sharpened...MAYBE a custom wooden handel like a soldier would have done while in the field). U know anyone who can do this or at least get it straight. There's also slight damage(additional more sever bending)on the blade i think is contributing to the warp
Can you do this with any success with a standard ball peen? $120 is more than I’ve spent on steel so far😬. Thanks for the video.
No, in most cases the steel is harder than the head of the ball peen.
Got the mako today. First impressions is ,Whoa. Things c an be made like this?
Bro get flooded with work.
Does the hammer need to be carbide tipped?
Yes, it needs to be considerably harder than the material it is striking.
Hi Gary, I think i can shed a little insight into what is happening to fix the warp. You mention that the carbide hammer leaves some very small divots, which means that when you strike the surface of the steel, you are locally creating stresses beyond the yield strength and flowing material away from the point of impact. This is why the steel chips if you strike too closely to an edge: there is no support steel in the cutouts to limit the yield and the steel is displaced beyond the breaking strain.
Here is the explanation of the (un)intuitiveness of this repair:
Like you said in the video, most folks would think to put warp-side down, where the center is bowed up, and then strike the bowed-up center to flatten the piece. This strategy assumes that the warp can be corrected by 3-point bending beyond the yield strength of the blade to induce a new warp to cancel out the existing warp. One can think of a downward bending moment on a blade (or a beam) as creating strain that varies from positive (stretch) to negative (compression) from the bottom surface to top surface, respectively. With a hammer blow on a flat surface, you will never be able to fully flatten a warped blade because you can only have get the blade to temporarily flatten during impact, but the elastic response of the steel will cause it to rebound.
When you put the warp side up, where the blade is curving upwards, the bend in the blade can be thought of as the top surface of the blade being too short relative to the bottom surface. This variation of "too short" to "too long" across the thickness of the blade is the bending moment we need to relax out of the blade. By striking the top surface of the blade with the hard ceramic ball, you are locally yielding the blade and causing steel to flow outward from the point of impact; namely, you are causing the steel at the surface of the blade to stretch out and away from the point of impact. Since the blade has been placed warp-side up, which is the "too short" side, by hammering around on this surface we are stretching it out, thereby removing the bend.
I cannot say whether the localized residual stresses that the hammering creates is "relaxing" out the residual stresses from the heat treat that caused the warp in the first place, or whether there is ample residual stress from the heat treat that is in a push-pull balance with the residual stresses from the hammer blows. I guess you will find out when you have the blades ground to their final thicknesses whether the heat-treat warping stresses permeate throughout the thickness of the blade while the hammer blow stresses are just at the surface. If that is the case then you might find the blades start to warp again when the surfaces are ground.
Looking forward to these makos. I'll be taking one with me on a boundary waters canoe trip this summer if they are ready by then.
You are correct there sir *I think*. Just don't ask me to make one. I've had 2 people try and fuck Gary over cause I'm in a non-profit hobby deal. It's incredibly fucked up to even ask. :| Albeit I doubt he would care about 2 knives, it's the principle.
Thanks. awesome
Do you think someone could make this work with a regular ballpeen hammer? Or do you think the carbide is completely necessary?
You should easily be able to do it with a regular ballpeen hammer as it's going to well exceed the transverse yield strength of knife steels? I don't think hardness matters, energy/force does. **JUST A GUESS** *not a professional*
straightening hammers for cultery are made in japan commercially.
Why don't you show us some new blades at the knife center
As you know Murray Carter also had made a limited run of Tagane hammers. Murray's hammer only had one carbide on the end and he was selling them for $250. Look up "Trow and Holden Carbide Mill Pick" . You could take this hammer by Trow and Holden and shape/grind either end of the hammer heads to your liking. It's only $167 for two ends that could be just like the ones Murray made up, but just a longer head. You could make one having one end just like the one Murray made which is somewhat sharp, and the other more rounded off as to not leave the marking on the blade like Murray's. The "wedge" shape allows more precise control of your desired bend.
I found that keeping all my blades clamped together from the quench to the last temper cycle really helps with the warping.
Works really good with thicker shorter knives, kitchen knives are a different story
If you were to leave a minor warp would it effect the toughness of the blade?
Do you have those water jetted? Apparently grinding at lower rpm and or under water can help reduce some stress. The less stress you put the steel in pre heat treat the less they will warp as bad. Does Peter's offer a stress relief cycle? I've also heard of Vibratory Stress Relief.
Don't hit it so hard. More lighter taps leave less deep indentions which less stock removal is needed. Plus less chance of chipping.
I'm pretty amazed and also certain I could make hammesike this but much cheaper. Plenty of busted carbide bits around the machine shop.
Great tip! I still need practice, i broke two knives 😓😓😓 hope to get better at it soon
What steels, in your experience, have the highest propensity to warping?
Very interesting Gary. How sure can you be that micro cracking is not a possibility when doing this?
I had a similar concern whether it caused any damage to the steel. I actually ran it by the designer of the steel only to learn that he endorsed the method. I am pretty confident that it is not creating those issues, the biggest issue is grinding out the divits, but in the case of my usage that’s no problem.
@@Creelyblades Very interesting and could be a game changer! So I assume these are the Magnacut Mako's then, and Larrin reckons this would be just fine?
@@burtjoubert yes, Most of the Magnacut makos are at the grinder, but I had about 55 warped ones that I had to hold back. I lost about three of them that I just could not get straight, but otherwise now I have reclaimed 53.
@@Creelyblades Wow, it's very curious that so many Magnacut heat treats warp. Any ideas why? Could it be Magnacut itself, or just the heat treat guys getting used to it?
@@burtjoubert It is likely something about the process of rolling the steel into sheets.
Mr creely was the larger knife that you worked on, was that my magna cut folklore.... Order no 413 meirion Jenkins south wales britian
It was the group yours is in
How is that possible? in reality that steel should shatter, that's cool!
It's basically cold forging
Are you having to surface grind to get the marks out
I do, about .002-.005” divet
Is this after tempering?
Yes
Anybody know if this work with a regular ball peen?
I have a massive warp on an 11” blade I’m working on. I havent tempered so I’m going to try the trick of putting the blade on a piece of angle and tempering maybe this will work to get wtvr warp is left out?
Straighting in the temper is a better first choice, but it does not aways work, or it is not perfectly straight. A regular ball pean hammer will not work. Also you would not do this until after the temper cycles.
It will not work post heat treat, most ballpeen end are softer than the blade.
@Maciej_Jan_Dlugosz if you were straightening a kitchen knife that was already hardened, and bent in the process of use. It was simply the mechanism of bending it back using the ball peen hammer. This technique is something entirely different.
Gary are you using the 4oz or the 8oz hammer? Thanks buddy for info
Both, but I favor the 8 ounce, and I made my own 16 ounce
@@Creelyblades thanks friend for your reply big help. Have a blessed Thanks Giving