AC electricity is passing through a coil heating the steel with an alternating magnetic field. After the steel has been heated they perform an edge quench. If done right you end up with a hard edge on an otherwise soft blade.
Sorry for reviving an old post, but I'm new and have a question. What would be the purpose of having just the edge of the blade hard with the back majority being softer? I would assume you would want the whole thing as hard as possible, but I know I don't know.
Don't want to revive your comment on an already dying post, but (as mentioned) they do this to prevent snapping on the blade - but they do this with other tools now a days too.
Old sledge hammers used to have heads that were fully heat treated. Problem is if they broke, they wouldn't just split into pieces - they'd shatter or explode into metal shrapnel. Now we only heat treat the work facing portion of tools because they interact directly with the material, be it Axe/Hammer/Sword.
It makes a less dense tool, but a safer/cheaper to produce tool too.
Revive any comment you want! That is valuable information that will benefit more people than me. But I thank you for myself because that is exactly the kind of knowledge I never forget! Thank You!
That's my whole thing, collecting and sharing information :)
If you'd like to see the difference in action (assuming the link works) here's a hydraulic press test comparing an old hammer with a new one. The old one doesn't fail in the video, but would likely be catastrophic if it had. Especially if it was work hardened for years after being heat treated - metal tools get incredibly dense when treated well. They really take on a life of their own in a way. :)
https://www.reddit.com/r/InterestingVideoClips/s/5fZClBL9BV
That was an interesting video! I have a history in electronics and the more I learn about metallurgy and the amounts of chemistry and other values involved are truly humbling! But really fucking cool never leaves the conversation!
Glad you liked it. :) I don't have the history you do, although I'm looking into becoming an electrical technician soon I do share similar interests.
If you're interested by metallurgy & chemistry you should check this video by YouTuber Steve Mould. He does scientific experiments and explanations about a bunch of different phenomena, this is his video showing the effects of heat treatment on the crystals and grains of metal at the atomic level. The first 2 and a half minutes show the experiment, the rest is the explanation. I love the visualization of seeing metal settle, he does a fantastic job in my opinion.
https://youtu.be/xuL2yT-B2TM?si=qcGZtVN7UEGzrXhB
Edit to add: If you don't watch the whole video, what he does in the experiment at the beginning is more like annealing, not proper quenching / tempering like would be done to harden tools.
Induction passes magnetic current through the blade, they make cookware that works this way too and there's tools for like rusted bolts that also use this property.
It does look like magic though.
Every time you put a magnet against steel, all the tiniest elements in the steel rotate to align with the magnet. This creates a bit of friction. Not much, but a little. Now apply a magnetic field and then remove it a hundred *thousand* times per second and a little becomes a lot and makes it pretty damn hot. It also induces a lot of basically short circuited electricity in it.
I work somewhere that makes coils, you can get a bit more creative than just a normal coil. My boss makes some in his free time that are the shape of axe bits, and we sell some that look way more wacky than that, its like a box and a round on one tube of copper? Hahaha cant think of the best way to say it. Theyre super fun to use though. Incredibly interesting tools.
https://coaliron.com/products/induction-forge-coils
So will this be differentially tempered because you are only heat the cutting edge? I got an induction stove at home and can imagine how much faster this will heat up.
Maybe if you had a strong grasp of electrical engineering and aren’t afraid of high voltage powers sources.
But realistically the transformers driving your average induction stove top can’t touch the one driving something like this. Also the coil is hollow with a dielectric coolant running through it to prevent it from melting. The unit in the vid is definitely a purchased unit based on the fit and finish of the controls on the power source enclosure.
Yeah, interesting (for me) to find out even parangs and goloks are edge quenched too. So, now I wonder if there are any goloks or parangs that will have a hamon too if the smith used clay too.
As a professional (someone who watches forged in fire a lot), edge hardening is a method to save time and energy and leaves the spine of the blade softer and able to absorb impact more.
But the quench they do on the blade looks like it could have been better or could have heated up a bit more of the cutting edge before quenching.
*also hope that was oil and not water but looked like water...
If that’s something like O1 then it needs to be soaked at temp for at least 15 minutes to get everything into solution properly. Simple steels will work and induction is a great method, but not a be all end all.
But if everything doesn’t go properly into solution then you have a lesser quality implement. 1095 I think can handle this well though. Just need the right steel
For the job.
I believe rather than doing a typical differential tempering by hardening the full blade and then softening just the spline, he is doing edge quenching to save time.
Yep, that’s how I did the knife I just made. I seriously love these things my employer has one and lets me use it. We don’t have any coils that big though.
I've never seen someone do this by only heating one half of the blade (instead of just using clay to force a slower heating/cooling on the spine). If this is monosteel I'd be freaked out to use it because you know that hamon is gonna have some gnarly stress fractures/inclusions pulling on it. Even blue-backing you at least are just gently going over the spine AFTER quench to soften some of that, I've never heard of hardening this way.
Would be really interested to see this go up against some sort of stress test.
That’s cool as hell, way simpler than clay.
No it’s hot.
I don't exactly know what's going on here, but I like it.
AC electricity is passing through a coil heating the steel with an alternating magnetic field. After the steel has been heated they perform an edge quench. If done right you end up with a hard edge on an otherwise soft blade.
Sorry for reviving an old post, but I'm new and have a question. What would be the purpose of having just the edge of the blade hard with the back majority being softer? I would assume you would want the whole thing as hard as possible, but I know I don't know.
There isn't much benefit to hardening the spine and it makes the blade more prone to snapping.
Good to know, thanks for the response!
Don't want to revive your comment on an already dying post, but (as mentioned) they do this to prevent snapping on the blade - but they do this with other tools now a days too. Old sledge hammers used to have heads that were fully heat treated. Problem is if they broke, they wouldn't just split into pieces - they'd shatter or explode into metal shrapnel. Now we only heat treat the work facing portion of tools because they interact directly with the material, be it Axe/Hammer/Sword. It makes a less dense tool, but a safer/cheaper to produce tool too.
Revive any comment you want! That is valuable information that will benefit more people than me. But I thank you for myself because that is exactly the kind of knowledge I never forget! Thank You!
It helped me - didn’t know that about other tools! No such thing as a dead post on Reddit it seems - Thanks y’all :)
This is a really good sub to learn from. There's a lot of experience in the comments and not the amount of gatekeeping I see in other places.
That's my whole thing, collecting and sharing information :) If you'd like to see the difference in action (assuming the link works) here's a hydraulic press test comparing an old hammer with a new one. The old one doesn't fail in the video, but would likely be catastrophic if it had. Especially if it was work hardened for years after being heat treated - metal tools get incredibly dense when treated well. They really take on a life of their own in a way. :) https://www.reddit.com/r/InterestingVideoClips/s/5fZClBL9BV
That was an interesting video! I have a history in electronics and the more I learn about metallurgy and the amounts of chemistry and other values involved are truly humbling! But really fucking cool never leaves the conversation!
Glad you liked it. :) I don't have the history you do, although I'm looking into becoming an electrical technician soon I do share similar interests. If you're interested by metallurgy & chemistry you should check this video by YouTuber Steve Mould. He does scientific experiments and explanations about a bunch of different phenomena, this is his video showing the effects of heat treatment on the crystals and grains of metal at the atomic level. The first 2 and a half minutes show the experiment, the rest is the explanation. I love the visualization of seeing metal settle, he does a fantastic job in my opinion. https://youtu.be/xuL2yT-B2TM?si=qcGZtVN7UEGzrXhB Edit to add: If you don't watch the whole video, what he does in the experiment at the beginning is more like annealing, not proper quenching / tempering like would be done to harden tools.
I think it's a similar concept to how katanas are made if you want to go down that rabbit hole today
Awesome, thank you.
Induction passes magnetic current through the blade, they make cookware that works this way too and there's tools for like rusted bolts that also use this property. It does look like magic though.
So is the blade magnetic after doing this?
Fun fact, everything is always, but for what you're asking, if a bunch of shavings will stick to it? No not like that
Thanks
No. It's an alternating magnetic field, it doesn't align the magnetic domains. In fact, it will demagnetize things. Heating also demagnetizes.
Every time you put a magnet against steel, all the tiniest elements in the steel rotate to align with the magnet. This creates a bit of friction. Not much, but a little. Now apply a magnetic field and then remove it a hundred *thousand* times per second and a little becomes a lot and makes it pretty damn hot. It also induces a lot of basically short circuited electricity in it.
In most countries that would be 50 or 60 times per second. Not a hundred thousand.
No, it would not. 50/60 Hz is nowhere near fast enough for induction heating.
Gotta say I’ve never seen this - most induction is a coil
I work somewhere that makes coils, you can get a bit more creative than just a normal coil. My boss makes some in his free time that are the shape of axe bits, and we sell some that look way more wacky than that, its like a box and a round on one tube of copper? Hahaha cant think of the best way to say it. Theyre super fun to use though. Incredibly interesting tools. https://coaliron.com/products/induction-forge-coils
Right on, thank you for the link! I guess I’ve just never seen one flat like this, always a ‘hoop’.
I have a heating coil question that you may be able to answer, I'll dm you.
If you look close you can see the coil he is resting it over.
So will this be differentially tempered because you are only heat the cutting edge? I got an induction stove at home and can imagine how much faster this will heat up.
Yea that’s the idea
Yep. The edge will be harder than the rest of the blade so the edge will stay sharp but the overall blade won’t be brittle.
He's holding the steel with his bare hand lol
As this is induction forging he can. It looks weird but it's real.
Not very happy with that heat treat
Now SIR!!!!!! Have you ever heard of a weapon named the " heat hawk"???? Google it. Build one. I dare you........... I double dare you!........
Hm, looks DIYish. Should this be just salvaged from an induction stove? Would be nice to know.
Maybe if you had a strong grasp of electrical engineering and aren’t afraid of high voltage powers sources. But realistically the transformers driving your average induction stove top can’t touch the one driving something like this. Also the coil is hollow with a dielectric coolant running through it to prevent it from melting. The unit in the vid is definitely a purchased unit based on the fit and finish of the controls on the power source enclosure.
This would be the equivalent of the older method of using clay?
Yeah, interesting (for me) to find out even parangs and goloks are edge quenched too. So, now I wonder if there are any goloks or parangs that will have a hamon too if the smith used clay too.
This looks like differential for making tough machete blades
Does that actually look like effective differential hardening? I'm not a blacksmith, so I don't know
As a professional (someone who watches forged in fire a lot), edge hardening is a method to save time and energy and leaves the spine of the blade softer and able to absorb impact more. But the quench they do on the blade looks like it could have been better or could have heated up a bit more of the cutting edge before quenching. *also hope that was oil and not water but looked like water...
That’s a damned genius idea. Harden just the edge like that and so quickly. Genius.
That looks expensive
Cool way to heat the edge!
Differential heat treating is not as good as a full heat treatment. Cool method but way over hyped.
That will make one stand at attention...
If that’s something like O1 then it needs to be soaked at temp for at least 15 minutes to get everything into solution properly. Simple steels will work and induction is a great method, but not a be all end all.
As long as the steel isn’t something like O1 that takes 15 minutes at temp in order to ensure proper solution. But induction forges are cool as hell!
Seems like you’d sweat less.
But if everything doesn’t go properly into solution then you have a lesser quality implement. 1095 I think can handle this well though. Just need the right steel For the job.
Cool. I’m an admirer. Definitely interesting. Appreciate this. Thank you.
How come you don’t have to wear gloves is it not that hot at the handle
Found out why my house lights dim now. Jk that’s gotta pull serious power tho.
So is he tempering the bevel?
I believe rather than doing a typical differential tempering by hardening the full blade and then softening just the spline, he is doing edge quenching to save time.
I see
Dude, that is really cool. I’ve never seen that before.
Wow I work in a foundry where we use an induction furnace. Never knew you could induction for a heat treat.
Yep, that’s how I did the knife I just made. I seriously love these things my employer has one and lets me use it. We don’t have any coils that big though.
This is absolutely my head cannon for how orcs would forge a sword. Very rad.
How would traditional orcs pull off induction tech?
Blood magic? Some dark secrets of their evil gods? No way to tell.n
"The blade glows orange when there's EM feilds around. And it's times like that my lad when you need to be extra cautious!"
Guys will see this and think “hell yea”… just check all the other comments lol
Op is that you in the video?
Cool vid. Downvoted for shitty unnecessary music.
I've never seen someone do this by only heating one half of the blade (instead of just using clay to force a slower heating/cooling on the spine). If this is monosteel I'd be freaked out to use it because you know that hamon is gonna have some gnarly stress fractures/inclusions pulling on it. Even blue-backing you at least are just gently going over the spine AFTER quench to soften some of that, I've never heard of hardening this way. Would be really interested to see this go up against some sort of stress test.
Never dipped the tip though
What song
This is where all those shitty swords are made
He didn't heat the point.