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Ryan Smith

Help with a sword forge/heat treat oven?

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Hi,

I'm looking to build a 72 inch vertical forge with minimal volume. Does anyone have any advice on design?

 

My basic plan is to use a steel pipe (8 inch diameter) lined with 2 inches of Kaowool. This will provide a 4 inch diameter mouth that runs the length of the pipe, which will give me enough room to hang longer pieces for a heat treat soak. I'm not looking for forging heat, but definitely need to get thicker steel to critical temperature for heat treat. I'm thinking about using a 3-burner system, evenly spaced along the length of the pipe to try to keep my heat even but I'm concerned that I'll end up with nasty hot spots around the burners. Is there a way to even out the heat better? Is 2 inches of Kaowool enough to provide efficient operation? Any and all advice is welcome!

 

Thanks!

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I know Ben Potter has had success with a two-burner model. My own plan to be constructed one of these days will be a muffle furnace (pipe in a forge) type built like a downdraft pottery kiln. Burner at the bottom, exhaust at the bottom (with a stack to let the hot gasses out above head high), blade hangs vertically in a 2" pipe. That may be overthinking it. Todd Gdula made a pretty good one with a 55 gallon drum and no unusual arrangements for draft. Look at the pinned thread by TGdula about a drum forge.

 

Two inches of wool may be overkill for an HT furnace if you have good burners, one should be fine.

 

Oh, and 72 inches? That's a long blade! Mine will be 48" to handle longswords and rapiers.

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Another thing I'd suggest is a larger pipe than 8". You need internal volume, and to keep the blade FAR AWAY from direct heat. 8" with 2" of kaowool per side is too small for even knives. You simply can't avoid hot spots. 8" with even 1" of kaowool would even be too small in my opinion. The pinned threads are awesome resources. Here's another recent (horizontal) WIP by Daniel Cauble:

 

http://www.bladesmithsforum.com/index.php?showtopic=31716&view=getnewpost

 

The one thing you'll notice on all the effective ones is a larger diameter tank. I think the water heater tank is as small as I'd go, with 1" of kaowool. You can pick up junk ones for cheap, attach two together for your extra long oven.

Hope that helps!

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Might be an idea to have one burner at the bottom of your pipe ever so slightly off centre and allow the heat in the space to equalize before putting the blade in? That way no hot spots? Speaking from no experience at all!

 

James

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Remember that you do NOT need to harden and temper the tang! This was never done historically for many good reasons. Even a 72" Zweihander only needs heat-treatment over slightly more than half the length. (These had incredibly long grips and sizeable ricasso areas as well)

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