Heat treat oven build, few questions.

JTknives

JTknives

Joined
Jun 11, 2006
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I'm in the process of collecting the needed material for a heat treat oven build but I had a few questions.
First off I'm considering building a verticle oven as I like the idea of hanging the blade on a stainless wire that I can just grab with the tongs. I have used a few large horazontal ovens and use foil wrapping but I just can't kick the verticle idea. One reasion I'm thinking verticle is I can argon flood the chamber and if the oven is sealed from the mouth down it should hold the gas decently. But my big question is tempature spread over say 15", Will it be a problem. I'm thinking my lid will have one side fixed and the other side will move. I can hang my wire between the bricks, and once done slide one side open and lift out the blade. I always see oven for knives as front loading. But then I watched the peters shop tour and noticed thy hang there blades on a rack. I'm wanting to get away from foil hence the argon. I know when cooling air hardening steels I will get some scale but that's ok. The control we are working on building will have 2 thermal couples, one at the bottom and one at the top so temp spread can be monitored. Thanks guys for any help or advise you can provide.
 
Many sword and long blade folks use a vertical HT oven. IIRC, Sugar Creek made all their ovens so the ends were removable and they could be stacked.
 
Argon at ambient temp is more dense than air at ambient temp, so it will sink and stay contained. However, I'm guessing that argon at ~1500° will rise.
 
At 1500F the air will have a lower density ... just like the argon will. At any temperature, the argon will still be more dense.
 
No, because it isn't in the 70 degree outside air. It isn't even in 1500 degree air, as the air was displaced when the argon was pumped in. As long as the oven stays shut, it is an enclosed atmosphere. of mainly hot argon gas.

When the oven is opened, the gas would rise ( actually, the hot air does not rise out of the oven as much as the cooler and denser air flows in the oven and pushes it out).

Since the oven stays closed, and there is a slow flow of argon constantly added to replace any leakage, the chamber stays oxygen free until opened to remove the blades for quench.
 
Stacy E. Apelt - Bladesmith said:
It isn't even in 1500 degree air, as the air was displaced when the argon was pumped in.
Click to expand...

Right, which is why I said "1500° gas (argon and/or air)"


Stacy E. Apelt - Bladesmith said:
As long as the oven stays shut, it is an enclosed atmosphere. of mainly hot argon gas.

When the oven is opened, the gas would rise ( actually, the hot air does not rise out of the oven as much as the cooler and denser air flows in the oven and pushes it out).

Since the oven stays closed, and there is a slow flow of argon constantly added to replace any leakage, the chamber stays oxygen free until opened to remove the blades for quench.
Click to expand...

Agreed and understood. My comments were based on the notion that there would not be a steady flow of argon, since that was not mentioned. In other words, I'm encouraging a steady trickle of argon for the reasons you've outlined.
 
To reduce the temperature difference from top to bottom, could you use multiple coils, each with its own thermocouple and controlled individually?

Jesse Osufsen
 
P.Brewster said:
Right, which is why I said "1500° gas (argon and/or air)"




Agreed and understood. My comments were based on the notion that there would not be a steady flow of argon, since that was not mentioned. In other words, I'm encouraging a steady trickle of argon for the reasons you've outlined.
Click to expand...

Got it. I figured we were talking the same thing.
 
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