What a brilliant young man

"I have a home to go to, but I'm under no pressure to go there" Let's hope the Mrs. doesn't see that part Mr. Clarke! lol 😅

What would you recommend for human flesh? Asking for a friend.

Are you leaving the dowel glued in with the stack, drilling through the dowel.

How would compression affect this? Coming out of the oil and then clamping the steel between some plates. It might change the rate of success?

what is the hardness of that knife?

I always figured it's from uneven amounts of mild steel causing the steel to pull more in different directions, could be a good thing to try just edge quenching on to see if there's still splitting that occurs

Great, just learned what else my induction bolt buster can be used for.

I think what is happening here is the core fails in tension as the outer skins shrink around the brittle core. It is probably easier to visualize in the case of differentially hardened blades. In the case of hamons gone wrong with the classic hockey stick crack that opens up, the shrinking spine rips the hardened edge apart. Think about what happens to a katana when properly heat treated. A straight blade goes into the quench, it then curves down, curves back up past its initial state and is pulled out with the expected curve. So the edge shrinks first, then the back shrinks and finally but it is hard to see the edge expands putting the whole blade in compression on the edge to spine axis. If the edge cools too fast and starts transforming too much into brittle martensite before the spine shrinks then it isn't able to plastically deform and fails in tension. In short the differential shrinking rates are dancing around the martensite formation in the hardenable section. As to the san mai, thicker skins = more force and thinner less so the ratio of core to sides is a variable. Putting clay on the spine would delay the formation of martensite giving more time for plastic deformation to equalize the forces, etc.

Graham is looking well, great video!

If almost as if the Japanese put the Hamon on for a reason beyond decoration.....

ty for sharing

Always informative & scientific; info I find no where else. - The expansion of steel in the hardening/cooling process sheds light on steel cracking within & along crystal boundaries. - Micrographs reveal higher levels of cracking in outer layers of steel crystals of finished knife blades. - My thought & ( I may well be wrong ) is that this cracking may be related to the relative rapid cooling occurring in the blade grinding/profiling stage of machining. - I am also thinking rapid cooling occurring in the sharpening process may also result in steel crystal cracking along boundaries & within carbon structures near the cutting edge, diminishing cutting edge stability. - Can any one confirm or refute these concepts ?

I had the same problem so I know the pain when you almost had it... you'll do all and at the most important part of the process, it fails. So the solution I come up with is to put less carbon steel near the core and then went with mild steel and then again with carbon steel and mild again at the end. So W1 or 52100 as a core, bandsaw blade next(which i was told is 15N20, so 2%Ni there) then mild steel and repeat or not. Good heat, none flux, no delamination no core cracking, no problems.

interesting, obviously a complex subject

I occasionally get cracks from the knife edge up when I'm doing Hamons with W2 and sometimes other steels. Maybe 1/5 or 1/6? Any ideas?

I'm no metallurgist but I have hardened many stainless/wrought iron clad high carbon core - san mai blades. I've also had this splitting happen to me. The way we've managed to minimize it is by first exposing the core steel on the cutting edge of the knife profile, then we make sure to only edge quench the blade, about 40% of the way up the blade. We quickly correct any warps while the blade is still hot and then allow it to cool to the touch. As soon as we can comfortably pick up the blade we put it into the tempering oven and relieve the stress on that core steel. If the blade is left out too long after quench - that is when that splitting it going to occur. If you find that the splitting is occurring during the quench, then it's most likely due to too fast of a quench medium.

Great video! Interesting topic! I believe I’ll be sticking with two Hardenable materials ! 👊

It doesn't happen to me enough of the time that I can really put much of a guess on 'why' it just sometimes, randomly seems to happen. Vast majority of the san-mai style I've made lately is 1018 cladding, layer of nickel (because shiny) and 125SC core, really fine slip of ATP over the whole lot, 10min at temp and a water quench. Wasn't a single crank, bang, delamination or warped one out of about 10 in a row. Now I'm not being a smartarse about it, but I fully expected half of them to pop on me! Literally if I got 40-50% usable out of that batch it was going to be good enough. Other side of the coin, whole heap of 1084 clad with 26C3 core, 10min soak in a fast-oil quench: almost guaranteed that it'll work as they're so close in terms of heat treatments Nope! A little over half of them had something completely crap-out on me. either an entire side peeled away on one, crack right down the middle or ended up with something going bananas. There was a lot of very short knives made that day and the art-bin got filled up with shame. Any advice? Yeah- make 2 or 3 of the same one and hope 1 survives! If they all survive that's great but I wouldn't count on it

What do you mean by putting a reactive gas in the canister? Since gas expands when heated, it will tend to 'blow out' welds. So how do you keep a canister filled with gas intact while heating it to the forging temperature?

Very helpful info and video! Does canola oil ignite at around 450c as well? That’s all I’ve got so if it works the same I’ll try making some sort of press.

What's the size of material that you started with?

Wonder if you could do that with cork

I have both stainless and high carbon steel knives of all sizes. Recently made a stainless steel dagger shesth knife. Stainless does take a lot of work to sharpen. I use me carbon chef knife for almost everything. It is blackened of course and gets dirty. I decided to super clean the metal including scratches, etc. After metal clean and dry i mixed a bit of 2 part epoxy and evenly spread a thin coat over the blade. When cured I put the knife back to general kitchen duties. Knife slick durable voating rasy to clean and s handy oil stone keeps it sharp. I am trying to figure out what to transform my useless knife honing steel into that's interesting.

Thank you for the detailed information!

I was one of those who touted the supposed merits of carbon steel for years, up until recently. Having taken in some info on metallurgy, now it seems like all most carbon steels are good for is a nice patina. I confess, I do like a good patina.

Would O1 make a good sword? Perhaps of the more ridged type such as Japanese style? Would O1 be good for bushcraft knife in pattern and geometry similar to Becker BK-2? What about bushcraft axe/hatchet?

Better than a magnet is salt melting on your steel. The one option i didnt see mentioned was templisticks.

Which Glue you use

This video just proves to me that Tobias is definitely my favorite bladesmith GURU

Why do people like the Scandinavian grind for bushcraft knives?

Also what is crazy is most of are machining technology for a lot of the metal processes are old 80s or older like 50s because they last for ever, Cnc are new,but they break a lot and have to be replaced every ten years

I know some bearings have silver inside them for lubeing the balls,crazy shit

I worked with heat treat department for a us military ball bearing maker,they would heat up the metal to hot as hell,they freeze it with nitrogen,that is about as strong as it gets,then dip it in oil

The possibility to make over 2 millions knives and they are differents each other.

This man is an absolute bad ass.

So true, sir, about the part that edge quenching carbon spring steel is on point! In South East Asia, the preferred recycled steel for forging is carbon spring steel, and all of the blacksmiths choose this tech. I learned a lot about steel today.

Thanks. This guy is fantastic

What are some of the best powder met stainless steels for large knives and machetes?

That was a brilliant lecture. Thank you!

Great Video, well done! My question is where you came up with the "98%"? If you're going to use a stat, make sure you can back it with qualified data. The truth is, I have been coal forging JUNKYARD (meaning I have no idea what it is) steel for years and I have never, not once, had a knife break from being used (be it as a knife or a crowbar or a thrower...) because as long as you heat treat and take the right steps to deal with the metal, you'll be fine.

Hi. is there any chance you can do more videos on handle making/stabilizing/wood dying? your video on how to stabilize wood for beginners was amazing and id love to see some content expounding on that. you can have the nicest knife with the cleanest lines ever but if the handle isn't up to par, it detracts from the entire thing. I imagine many people would appreciate some more content on that

This is undoubtedly the best knife making/sharpening chanell that I discover this year. Love it!!!

This video it's a true diamond in the sea of the knife sharpening videos.

Thanks. This is useful. I love my stainless gyuto knife I use when I use to work as a sushi chef

Very informative, thank you. I will try this for my next forge weld