Heat treating with a torch?

SkagSig40

SkagSig40

Joined
Feb 1, 2001
Messages
2,671
Hi guys! I just bought a villager and the blade is very soft. I saw an article in Blade mag. on heat treating with a torch but I can't find it. Can anyone give me all the details I need to get this done? I do not want to remove the handle. I basically know how to do it, I just need the details like how close do I hold the torch and what type of oil do I quench it in. Also do I get the blade red hot or not? Thanks for any help!!!;)
 
SkagSig40, you will have to REALLY CAREFUL if you're going to try to re-heattreat with the handle still in place. You will be getting the cutting edge of the blade up to 1500-1600 degrees (the exact temperature/moment to quench can be determined with a magnet. High carbon steel will become non- magnetic when it reaches it's critical temp.) This high of a temp is more than sufficient to melt any epoxy or resin that is holding the blade's tang in the handle. This heat can also crack your handle if it's horn, and melt any soft solder that might be used on the bolster. If you think that you must do it with the handle in place, wrap a wet rag around the area of the cho and bolster so that less heat bleeds up the tang. Play your torch up and down the edge as if you were painting it. Be careful near the tip as it will have a tendency to heat quicker than parts of the blade with more mass. The area that should be heated should extend at least 3/8 of an inch back from the edge. Once this full length of the edge is at a cherry red(non magnetic is a more accurate test for critical temp) quench the blade in ATF, motor oil, or a mix there of. Make sure you have an extinguisher handy because the oil has a good chance of flaring up. Because of this use ONLY a metal container for a quench tank. After hardening, polish the blade and completely degrease it . Now you need to temper the blade. Play your torch along the spine of the blade until you see oxidation colors form on the blade. It will start with light yellow and progress through various shades until it reaches bronze, brown, then blue. When the heat has traveled from the spine to the edge and caused the entire edge to turn bronze, quench it again in the oil. Repeat the tempering steps two more times. If the blade is made out of high carbon steel and you did everything right, youshould have a very tough blade that will hold a good edge. I really suggest you practice these steps on an old file or some other scrap of steel before trying it on your villger. Good luck, have fun, and be CAREFUL!!! :eek: Hot steel and flaming oil have their own methods of ruining your day if you don't mind your p's and q's. ;) stevomiller
 
That reminds me of the time in high school I decided to reforge the tip of a screwdriver that had been reshaped too many times. I figured there was no need to remove the handle because it was a long screwdriver (maybe 9" 23cm not counting the handle) and I was only going to heat the tip. The wooden handle caught fire so I stopped heating it and blew out the flame. It instantly relit -- the shaft was still hot. I blew out the flame a couple more times and it relit instantly each time, so I started walking across the shop toward the sink ... blowing it out again every step or two ... the whole shop was rolling on the floor by the time I reached the sink and put it out for good. The inner half or so of the handle was charcoal; I had to make a new handle for it (steel, naturally -- I do learn from experience ... eventually)....

Take the handle off first. It's not that hard -- somebody posted about it -- just put it in boiling water and the Himalayan epoxy will soften up, and you can reuse it.
 
When I "try" to reharden I put the handle in a can of water. I use vice grips on the back of the blade to hold the knife. Use the heating technique stevo described but I quench with water like the kamis do. I figure my success rate is about 75%.
 
If the heat treatment of your blade is faulty, return it to the seller and ask for a replacement or refund.
Not only will trying to harden it with the handle on ruin the handle, the size and mass of a khukuri blade pretty much guarantee that you can't get an even heat on the edge with a torch. You'll probably just get hard and soft areas on the edge with some drastic grain growth in spots to make the blade weak and likely to chip or break.
Heat treating with a torch (without the handle) works on smaller blades with practice, but is VERY difficult on large curved blades.
 
Protecting the bolster-handle during heat treatment might be done with a wrap of children's dime-store modeling clay between the heat and the bolster.

I've tried this one time (soldering a guard with a small torch and silver solder) and it appeared to keep the heat away from the blade - at least my test file indicated no change.
 
Welcome to the Cantine, Art. This is a village model we are talking about.

I'll agree that it is not an easy job but it can be done.
 
Ok thanks guys!! I'll think about this one! I think I'll give it a try just for the experience!!
 
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Skag you also need to know that the Cherry Red we speak of Is Not A real Cherry Red like you see on a Bing cherry.
It's more the red that you see on pie cherries and is pretty close to a neon orange.
The magnet is the best way to tell when the steel is at the critical temp and is the method I use.

And if you're gonna use a home style butane torch please bear in mind that it just won't get the knife hot enough.
They will work on thin and narrow blades but not a khukuri blade.

So if you're dead set on doing this to the little villager find a friend that also has a butane torch,then go get 2 bottles of MAPP Gas and do like Uncle Bill has said.
"Use the visegrips and a bucket of water to keep the handle and the top of the blade cool."

Get your friend to help and use the MAPP Gas torch on each side continually moving the flame up and down the blade slowly and in unison at an angle so you won't burn one another and when it gets critical temp dunk it in the oil or water.
Oil is best for a beginner but have a lid that will fit tightly over the bucket or whatever you have the oil in just in case you have to put out a flare up fire.

And you don't have to get the steel polished, just get it back to the grey color all over so you can see the colors come up when they start changeing.
Sandpaper works alright for that.
The village blade is gonna be rough anyway. :D

And it's a good idea to have a bucket of water handy to dunk the blade in when "drawing the blade" because when it gets to the light straw to bronze color it will continue to change rapidly unless cooled immediately, ruining all your efforts.

Personally I would leave it alone because sometimes it's nice to have a blade you can sharpen with a couple of rocks, One for an anvil and another for a hammer stone.
You can gently tap an edge back on the knife getting any impacts out.
Then you can us an abrasive rock like sandstone to put an aggresive edge on the knife.
A lot of indigneous people around the world use this method quite successfully.

Try it for a while first and then decide if it's worth going to the trouble for.:D
 
Since it's already a project khukuri, I would probably try and bring out a hamon on it when you're done. For one thing, it will give you some indication of how well you did on hardening the blade.

Bob
 
Thanks for good help and advice, all.

Chris has enough khukuris that he could stand to have one "maasu katne" (meat cutter) in his collection. It's a lot of work and maybe you'll have success and maybe you won't -- especiallly if you are a beginner. It took me five or six tries before I got one right.
 
Thanks for the welcome. I've been lurking here quite a while, but never posted before today.
Please heed all the cautions when you attempt the hardening, and wear gloves. If you quench in oil you are very likely to get a surface fire coming up to your hand.
Yvsa brought up tempering the hardened blade, which further complicates the process. This is another step you probably want to practice before trying on your khuk.
If you plan to submerge your blade during any of the process you'll need a surprisingly big container if you want to submerge all the blade at one time. Please don't ask how I know.
If you do as the kamis have learned to do over the centuries and use water, remember these details:
They use a directed stream of water and don't just pour out of a bucket.
They direct the flow of water at the thicker ridge behind the edge, not at the edge itself.
They carefully watch the tempering heat travel toward the edge and pour water to slow or stop the heat as needed.
Finally, before you start use a file to check the hardness of the spine and edge of your blade. There should be a noticeable difference. If there is not, the maker may have used a scrap of mild steel which can never be hardened.
Whatever you do, don't let someone like me prevent you from trying new things. Being cautious doesn't mean doing nothing.
 
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Welcome to the Cantina Art.
Both good posts and it's good to see a new forumite that knows something about hardening steel. :D

How are you on sharpening?
Will and myself have been needing a replacement sharpener that really knows what they're doing since Uncle Bill Always sends us the dullest khukuris.:rolleyes::D

And besides we can always learn new methods as well.;)
 
Thanks again for the welcome.
Yvsa, my wife would be quick to tell you that our kitchen knives are always dull, so my sharpening skills are only so-so. Besides, I can't believe Uncle Bill would sell anything dull.
This leads to something I'd like to say and ask about. Uncle Bill may want to put this in a new thread for discussion.
I was just out in the shop embarassing myself trying to forge a khukuri. That is a difficult shape to get just right - I still can't get the "elbow" on the spine to be farther out the blade than the bend in the edge.
Uncle Bill's khukuris are routinely forged by people considered "Third World" or "backward." That forging abiliity and the seemingly simple but really very sophisticated knowledge of heat treating are marks of incredible talent. Yet, Uncle Bill has written in the past that these makers are from a low caste. Is there some historic reason for this low social status or is that a mystery? Haven't metal workers and weapon makers been more respected in most other societies?
I hope the kamis know that there are people in other countries who appreciate just how talented the kamis are.
 
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Welcome to the Cantina Steve.:D
Sorry 'bout that.:(

Art if I'm not mistaken I "think" it is because the kamis work with material out of the earth that also lowers their standing besides being of the lowest caste, but Uncle Bill will have to say if I got it right or just imagined
it.:D
 
You've got it right, Bro. In the Hindu philosophy folks that work with animal parts and stuff taken from Mother Earth are down at the bottom of the ladder.

And, Art, as you'll often see me say -- join the club. I can't forge a khukuri either and a good kami makes it look so easy and simple! He can talk, smoke, brew a pot of tea on the forge, all while he's forging the blade and it still comes out exactly as he wants.
 
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I had forgotten about the animal part of it., But not bad for an od fart whose memory gets worse and worse every
day. :D

Art you're right about the Smiths and Armourers of days past.
And royalty usually retained the best and paid them very, vey well and sometimes gave them the most precious of things like diamonds and gold for a job done beyond their usual
talents.
They were held in the highest esteem.

Kinda strange about the Nepali way, but that's been ingrained and part of their culture for thousands of years.
And that's why the kamis have such a hard time understanding why we hold them in the regards we do and praise them and their work.
It's like someone mentioned a while back that when Uncle Bill was gravely ill they closed up the shop and went and prayed for him because without Bena they wouldn't be able to market their khukuris and would have to go back to starvation wages.

Hopefully there will be someone to step in and take Uncle Bill's place as the represenative for H.I. when he decides to retire or walks west.
Although I don't think there's anyone who could ever replace Uncle Bill in all the ways he means to us.

And Bro I ain't giving you undue praise, just stateing a fact.:D
 
I remember the picture of Sanu (before then an unremarkable kami?) presenting Uncle Bill with the first UBE, one of the great knife designs of all time. Now Sanu (my favorite) shows complete competence, finesse, creativity and spirit in his work.

Quality from all of Birgorkha skyrocketed after his visit, and I don't think that was a coincidence.

These are magic days for Birgorkha, the forum, for all of us (even lurkers, like me), and I'm making sure that I'm not missing them and enjoying them for what they are while they are here.

BTW, Art, I checked out the link in your sig, and I am impressed!

Chris
 
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