# Seriously hot



## bswartzwelder (Aug 22, 2015)

A few years ago, I built a small forge for heating some metals. I made it out of a discarded 20 pound propane tank with the top end cut off. I lined it with fire bricks around the side. Through the side, near the bottom, I put a 7 or 8 inch piece of 1 inch steel pipe. I had drilled a bunch of holes through the pipe. As I said, it exited the side of the forge near the bottom and I added some adapters so that I could couple a blow dryer to it to add forced air.

Recently, I made a container which I could lower into the forge. I took 8 pieces of steel cut into a trapezoidal shape. Top of each was 3.5 inches, bottom of each was 2 inches and height was 6 inches. All were 1/4 inch plate steel. Bottom was also a piece of 1/4 inch plate steel.


Today, I loaded the container about half full of chips which had been incinerated once, but had not completely turned to ash. Fired up the forge and set a piece of 1/4 inch plate steel over the container to keep the wind from blowing the ashes out. After I removed the container, I found the container bottom had melted. YES, MELTED! I don't know how hot things actually got, but the forge was running for a little over an hour. How hot it must have been to do this, I have no idea. Oh well, I guess it's back to the drawing boards.


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## Geo (Aug 22, 2015)

What are you using for fuel? Coal with even a bellows will melt steel.


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## bswartzwelder (Aug 23, 2015)

Using charcoal briquettes. Also using a blow dryer where no heat is supplied, only air.


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## 4metals (Aug 23, 2015)

I do not know the clearances between your furnace body and the insert you made but if a furnace design does not allow for heat to flow around the insert and rise out of the furnace, it will overheat with any fuel source.


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## bswartzwelder (Aug 24, 2015)

Yeah, I'm afraid I didn't build anything to any kind of plan. I used what I had on had or got from my local steel supplier. The bottom of the "cone" shaped container is an octagon with roughly 6 inches across the center. The top was wider and does not allow for a whole lot of room between the container and the forge when the container is sitting on the "arms" I welded onto it. The arms support the container and keep it from going all the way to the bottom of the forge. Strangely enough, it was designed to be a mold for aluminum where I could melt aluminum cans into an ingot. Never tried that yet. Plan to do it in a day or two. Just got a piece of 1/2 inch plat steel to weld to the bottom of the container. Just have to finish grinding away the old bottom.

I tend to learn a lot from my previous mistakes. The original forge would never have attained that level of heat, but I took it apart and removed the pipe which supplied air. Replaced it with an identical pipe where I had made all the air supply hole almost 3/16 inch instead of the original 1/8 inch. THAT modification made a huge difference in the heat output.


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## GotTheBug (Aug 27, 2015)

You have a hot spot. My furnace does that also, and if I let anything metal get close to the bottom, same thing happens. A graphite crucible will solve your woes.


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## Research135 (Aug 28, 2015)

Yeah. A porcelain soup dish will work too. Or a layer of Alumina based refractory cement, even better.


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