Chakma hardening?

firkin

firkin

Joined
Jan 26, 2002
Messages
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Are the chakmas differtially hardened like the blades, or do they carefully pour water over the entire outside, and allow the heat from the center to diffuse back so the entire exterior is hardened?

If differential, "edge" only, or "spine and edge"?

Maybe all or some of the above depending on the mysterious "kami factor"?

I've been trying different chakmas that I have and it seems the sides often get cut easier than one or both edges, particularly on those that I find to be most effective. Of course, this is complicated by how flat the sides are, and the different surface area in contact with the blade getting "chakma-ed".

But it would be nice to know what to expect, especially if one is having trouble getting a chakma to work well.
 
Sooner or later I know I've got to try it. I'm going to dunk my chakma handle in boiling water until the laha lets go. Then I'm going to reharden the chakma blade and reassemble it to the handle with epoxy. I might mess up an otherwise okay chakma, but there's some risk involved in any experiment.
BTW, my BAS chakma seems softer on the sides than the edges too, puzzling, very puzzling.

Sarge
 
hmm. Would cutting the Chakma from a piece of already hardened sheet explain this? Sincew I just got my one brick forge going, one of my first projects will be hardening some of the chakmas for my khuks. I'll let everyone know when I get around to it!

Pat
 
I don't know for sure. I was always so interested in watching them do the big stuff I never paid any attention to the kardas and chakmas.
 
I fired up the one brick forge yesterday - here are the results.

I took 2 chakmas, one larger one from a villager (grinder finish, and one from a GH khukuri set. I didn't want to risk any of my HI ones til I had the method down.

Methodology
1) remove handle
The GH chakma had a horn handle and small blade. I had already removed the blade with the bioling water method and polished it, so it was in OK shape.

The villager Chakma still had the grind marks and was still in the wood handle. A few seconds of heat on the blade from a propane torch softened the laha enough to remove the handle with a pliers.

2) heat treat and quench
I heated both blades to non-magnetic in my one brick forge. Both blades were quenched in tap water until cool enough to handle bare-handed.

Results
1) I tested the two blades on several pieces of flint I got with a firestriker.

The villager made a few small sparks, but would still be difficult to light a fire with.

No sparks at all from the GH chakma.

After testing the blades, I put the handles back on (I heated them on te barbeque I already had going). This part was way easier than expected. Chakmasa went back together with no problem.

Other observations
I filed and sanded the villager chakma after it was reassembled. While finishing it, I discovered a flaw in the blade. It went completely thru the blade (right to left), and extended up from the "edge" for about 3/16 inch. At this point it branched and runs parallel to the blade, about 3/8" in each direction. This parallel flaw does not appear to extend thu the thicknedd ot the chakma.

There are three potential causes for this flaw. The first possibility (unlikely) is that there was a forging flaw I had not observed before refinishing the chakma. the second (more likely) possibility is that the flaw is the result of a stress riser from the grindmarks. Wayne Goddard mentions that this can happen in his book "The $50 Knife Shop" :( I suspect that this may not be a problem with an HI Chakma, since they are fully finished.

Next time I'll:
1) I'll normalize and anneal the steel before hardening.
2) finish to remove grindmarks before hardening.

Hope this is of interest to some of you.

Pat
 
Next time use oil for the quench medium and you won't have cracking problems. Almost any oil or hydraulic fluid will do. Wear gloves and long sleeves, because surface flame-up is common with many oils.
If you really must use water, heat the water to near boiling and move the steel up and down while it's in the water. Hot water is a much less severe quench than cold water; the movement helps break the steam jacket which forms and causes uneven hardening.
The kamis are able to use water because they pour a small stream of water onto a large blade; this results in a slower quench than dunking would cause.
Generally, spring steels just don't like to be water quenched.
 
My preference would be to take a small fine Nicholson file and shape it holding it barefingered on a belt sander so to dip and cool it before it got hot enough to burn the fingers. Leave one side of the file with the cutting part intact, smooth the other side on a stone. Likewise the edges, to be sure the belt sander hadn't overheated it. Set it into a handle with epoxy.

Anyone see a problem with this?
 
Like Rusty, I make chakmas out of old files; however, rather than try and preserve the existing temper, I anneal the file so it can be shaped easily, and then harden and temper to light straw color.

I quench them in cold water, which is OK for the steels that most files are made from (typically something like AISI W2, which is suitable for water or oil quenching).

I only tried water-quenching 5160 the one time; and I still have the resultant blade fragments, to remind me not to try it again...
 
Originally posted by Tom Holt
Like Rusty, I make chakmas out of old files; however, rather than try and preserve the existing temper, I anneal the file so it can be shaped easily, and then harden and temper to light straw color.

I quench them in cold water, which is OK for the steels that most files are made from (typically something like AISI W2, which is suitable for water or oil quenching).

I only tried water-quenching 5160 the one time; and I still have the resultant blade fragments, to remind me not to try it again...
Click to expand...

So, guys - does oil quenching result in a chakma hard enough to strike sparks from flint? That's what I was after!

Pat
 
Originally posted by Outdoors


So, guys - does oil quenching result in a chakma hard enough to strike sparks from flint? That's what I was after!

Pat
Click to expand...

Pat if the steel reaches critical temperature , maybe just a tad above before quenching in warm oil it should result in steel hard enough to strike sparks with flint.
If it doesn't get hard then the carbon could be burned out of it making for softer steel.
 
Originally posted by Yvsa


Pat if the steel reaches critical temperature , maybe just a tad above before quenching in warm oil it should result in steel hard enough to strike sparks with flint.
If it doesn't get hard then the carbon could be burned out of it making for softer steel.
Click to expand...

Kool :)
Now that I don't have to experiment anymore, I can try to harden one of my HI chakmas.

Thanks, Yvsa!

Pat
 
Originally posted by Outdoors


Kool :)
Now that I don't have to experiment anymore, I can try to harden one of my HI chakmas.

Thanks, Yvsa!

Pat
Click to expand...
You're welcome Pat. You also have mail.:)
 
this may seem like a silly question so please remember i have never sharpened a khuk before, how do you use the chakma, i have read the bit on sharpening ect but am still scratching my head as to how to present the chakma to the khuk , ie sideways ,flat,bottom edge . top edge pics would be great for us newbies. i have just recieved 2 new khuks by bura 15inch ang khola and 16.5inch ww2 by bura and dont want to bugger them up. regards ghorka:confused: :confused: :)
 
Hi Ghorka:

Some basics, for you!
The chakmak is like a butcher's steel, or a steel you would find in a commercial kitchen, and is used as such. As opposed to a stone hone which removes metal, the chakmak realigns the steel edge without removing material.

Using the flat or the edge is your choice, experiment with both.
You can use the chakma on just about any knife

1. Hold the chakma in you steong hand (right if you're right handed)
2. Hold khuk in other hand, or immobilize with clamps or vice.
3. Run the steel along the edge, at an angle similar to the grind. the same angle that you would use a sharpening stone. You will feel the blade "grab" at the chakmak, and keep going with the chakmak until the blade no longe has that grab feel on the chakma.
4. Repeat the same number of strokes, same angle and pressure, on the other side of the blade edge.

Well, that's the quick and dirty version, with plenty of room ofr experimentation. There might be a knife sharpening forum on Bladeforums, and you can read all about sharpening using a steel.
Others to talk to on the finer points would be folks like Cliff Stamp, Yvsa, and is sounds like Rusty is, er,'honing' his honing skills.

All others, feel free to fill in the holes in this quick-n-dirty version...

Good luck!

Keith
En Ferro Veritas
 
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