aga
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Aga's Cauldron
Messing with making a furnace made from $40 of materials, i seem to have achieved at least 1100 C, possibly 1500 C using nothing more than charcoal
and a hairdryer.
The lumps in the photograph were copper pipe fittings.
The hole in the steel crucible explains why they're lumps and not nice castings.
I think the lump on the right has alloyed with the bits of Al in the furnace.
 
[Edited on 9-3-2015 by aga]
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Chemosynthesis
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What kind of insulation did you use around the walls?
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careysub
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You are building a crucible charcoal furnace, there are sites with designs for same.
Show us your design.
They have been used as far back as the iron age in China for melting iron for casting.
[Edited on 9-3-2015 by careysub]
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Zombie
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Most steel(s) melt @ 1400*. You were most likely wellll over that.
I'm assuming the melted area was where your forced air was. Why not pick up a cheap crucible now that you know your furnace works?
They tried to have me "put to sleep" so I came back to return the favor.
Zom.
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aga
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The broken crucible is on top of a leftover refractory brick, the rest of which are lining the furnace, held in place with refractory cement.
The picture says it better.
Amazing how cheap the bricks and cement were.
My first castings 
 
[Edited on 9-3-2015 by aga]
Edit:
there are three bits of rebar welded inside the steel cylinder to give the cement some way of sticking to the steel. No idea if it's really necessary,
just that i had some rebar, and had visions of the bricks & cement just sliding out one day.
[Edited on 9-3-2015 by aga]
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aga
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1400 C would make Steel pretty Hot and rather soft for sure.
Hit 1500+ and then it'll be a melt.
http://www.engineeringtoolbox.com/melting-temperature-metals...
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Zombie
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You've got some real cool stuff going on there.
Are there any houses for sale on your block? I imagine all of them are... 
They tried to have me "put to sleep" so I came back to return the favor.
Zom.
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Bert
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Mood: " I think we are all going to die. I think that love is an illusion. We are flawed, my darling".
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Hey, the property values in MY old neighborhood have been going up, ever since I moved away!
Rapopart’s Rules for critical commentary:
1. Attempt to re-express your target’s position so clearly, vividly and fairly that your target says: “Thanks, I wish I’d thought of putting it
that way.”
2. List any points of agreement (especially if they are not matters of general or widespread agreement).
3. Mention anything you have learned from your target.
4. Only then are you permitted to say so much as a word of rebuttal or criticism.
Anatol Rapoport was a Russian-born American mathematical psychologist (1911-2007).
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Zombie
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Judging by your signature, I can imagine why>
Some people just don't understand what Relaxing is all about. I have more fun trying to put out a major fire, than I do sitting watching a movie.
They tried to have me "put to sleep" so I came back to return the favor.
Zom.
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aga
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Houses ? Neighbours ?
What are those ?
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Zombie
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Perfect!
They tried to have me "put to sleep" so I came back to return the favor.
Zom.
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j_sum1
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They are on the other side of the horses that are galloping away at high speed.
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aga
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It's best to be on top of the horse, holding on for dear life when Galloping ...
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j_sum1
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With my horse-riding skills I would be on the underside of the horse hanging on for dear life. (And undoubtedly hitting my head on rejected
refractory bricks, failed experiments, explosion divots and piles of excrement awaiting conversion to nitric acid.)
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aga
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Failed experiments ? Can't see any of those around (they all went skywards).
The rest, well, yes, cling tightly to the horse's belly, maybe pray (the terrain here is far from flat).
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careysub
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I have been thinking about making a quick and dirty charcoal furnace for doing basic thermochemical reactions (the kind where you just need to get the
reaction mixture over a threshold, but no fine control).
My scheme was to just stack firebricks to make a square hearth, with the intent of using 2" iron pipe 18" long as the crucibles (about 900 mL volume
each). A group of four in the center would be the maximum loading.
Using 9"x4.5"x2.5" soft insulating kiln brick per layer, it would take about 72 of them to make a stack 22.5" high, with an interior 13.5" wide. At my
local pottery supply place this comes to about $250 worth of bricks, not really cheap in my book. Are there cheaper options? Is a solid kiln brick
wall overkill?
I could make the outside with about 100 cheap red bricks for $35, and use perhaps cerablanket or vermiculite insulating board to line instead of
firebrick. These products are only rated to about 1275 C though. Firebricks are sized differently from regular brick, and would not line the inside
neatly, are thicker (reducing hearth volume) and would cost more.
To feed air I would use another 2" iron pipe as the tuyere, feeding into a narrow trench across the bottom with half-thickness soft bricks with holes
drilled in them covering, to provide air feed across the whole bottom width of the hearth.
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careysub
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My scheme for a rough-and-ready temperature estimate is take a length of rebar, bend it 90 degrees to make a handle, wrap copper tubing around it in a
spiral, and insert into a narrower iron pipe in the furnace. One in the center perhaps, and one next to a wall.
By lifting the rebar out at intervals you could check to see whether it had reached 1085 C yet at different points in the dummy crucible pipe. This a
good temperature for many thermochemical reactions to complete, without risking melting the crucible.
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aga
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To make a Temporary, and very cheap kiln, just use ordinary bricks.
They will not last long, but they are a lot cheaper.
They're fired at very high temperatures anyway, so they'll not melt for sure !
I would suggest making a kiln out of cheaper bricks/blocks, and lining just the core with the more expensive refractory bricks.
Try to get your air feed to come in from the Bottom of the kiln, vertically, to create a more even airflow, therefore more even heating around your
crucible.
I'll try exactly that when a graphite clay salamander crucible arrives.
Edit:
For temperature, the colours of steel at various temperatures are widely available, e.g.
:http://www.stormthecastle.com/blacksmithing/blacksmith-steel-heat-and-coloring-chart.htm
[Edited on 10-3-2015 by aga]
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aga
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If you study Chemistry and still have Neighbours and Houses nearby, then you're obviously not doing enough experiments.
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