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Blade smithing

Chris Cramer

Super User
Vendor
Premium Member
16348771469754239956837959162332.jpg I've decided to forge a much larger blade now. Rather than a short hand knife I've forged this custom machete out of NitroV high carbon stainless steel. For more creativity I also tried using scaled juma for the handle, together with a brass hilt, and brass dragon head pommel. All three of those go very well with each other to make up a dragon handle.
I also decided to make the back of the blade serrated. The front edge of the blade has excellent edge retention by NitroV's high nitrogen and the hardening I performed.
I am very happy with the blade but it wasn't perfect, because I happened to make the mistake of tapering the teeth. With the tips of the teeth thiner than the blade they don't allow the rest of the blade to pass through when using the saw, regardless of how sharp the teeth are.
 
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PeterT

Ultra Member
Premium Member
Cool. What did you end up doing for heat treating on the blade? I think a while back you were looking for a service or considering getting some gear?
 

Chris Cramer

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I ended up purchasing an evenheat lb kiln, it works really well for precise heat treatment processes. Most high alloy steels like nitro v also require some type of protection from oxidation. I ended up using stainless steel foil to create an envelope for the blade. Cyro treatment is also recommended to bring nitro v to a hardness of 62 HRC. Normally liquid nitrogen is used for cyro treatment but I could not go that far, so I ended up laying the blade in my deep freezer for 24 hours. I can't say what the hardness is at, but my drill bits have almost no effect on it, and the edge was very durable when I tested the strength against some hard wood.
 

Janger

(John)
Vendor
Premium Member
Chris that's just fantastic. People would buy those if you wanted to make them.

Please post some pictures of your heat treat kiln and tell us more about it.
 

Chris Cramer

Super User
Vendor
Premium Member
The LB evenheat kiln is the long blade kiln, designed for heat treating longer blades. It works great for precise heat treatment, the electrical heating system gives you much better control of the process. The color of the blade after soaking it at 1980F for 15 minutes indicates that proper heat treatment is not done simply by bringing the blade to a bright orange in such high heat of a gass or coal forge, and quenching it in oil every time. Such hot hardening would make a very hard but brittle blade, and most likely cause many cracks because of so much stress in the metal.
 

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YYCHM

(Craig)
Premium Member
That's what I found when attempting heat treading. Went from straw to orange with no warning. Never saw red?
 

PeterT

Ultra Member
Premium Member
What is the greenish quench liquid Chris?
Are you doing any air quench on your blades?
 

Chris Cramer

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Premium Member
That liquid is just some plasma cutting fluid that comes frome my water table. Elmax stainless alloy can be plate quenched between two aluminum quench plates, which also does a good job of preventing warping by clamping the blade between both plates. Not every metal should be plate quenched or air quenched. some high carbon steels require fast quenching oil. As for the blades that I do quench in oil, I use a cheap alternative to expensive quenching media, such as canola oil as my quenching media.
 

Chris Cramer

Super User
Vendor
Premium Member
the green plasma cutting fluid is used mainly to prevent corrosion, so I also use it for quenching metals that can be water quenched.
 

SparWeb

Active Member
This might sound a little off the wall, but I noticed that you mentioned cryo treatment, and understandably, that can be expensive to set-up.

However, I have learned that large-animal veterinarians (cows horses etc.) have large Dewar flasks that they keep filled with nitrogen. From time to time they replace these flasks since the *uhhh* contents are *ahem* perishable and expensive. You might find a vet in your area with an old unused Dewar they would sell you. Just a passing thought since the central cavity of a Dewar tank is the perfect size for your blade. Apparently the vet can tell you were to get it refilled, and a recharge of Nitrogen isn't very expensive.
 

Chris Cramer

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The cryo treatment I carry out sometimes is only done in my deep freezer for extended periods of time which I don't know has much effect. I have never heard of a Dewar before, I'll look that up. I did hear that using dry ice would most likely be much colder, so maybe I'll look up how I should use dry ice for cryo treatment
 

6.5 Fan

Ultra Member
Premium Member
You can cool off a beer in under 3 seconds in a liquid nitrogen tank, go to slow and it explodes.
 

SparWeb

Active Member
How, would you liquify the CO2 and make it cold enough to freeze and solidify it?
Ummm... by using the process pioneered by James Dewar, as mentioned earlier...
KK just ribbing ya

For metal cryo treatment I think you need to dwell for some hours, so a quick shot from a fire extinguisher won't cut it.
You could start by talking to either Praxair or Air Liquide. They can tell you what cryo products they have, and you can figure out if that something you're interested in doing. The Dewar flask uses liquid nitrogen, which is about -200C. If you don't need to get that cold you can use dry ice at -80C. These are both fairly common and you just need to be equipped to handle them, you don't have to generate the gases or cool them. If you're reading a cryo treatment spec that uses some other temperature target, then they expect you to use some other kind of gas or liquid, but that could be much more difficult or expensive.
 
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