renovating my old smelter for A1 crucibles

[Jokke 2]

so since I am on holiday I started a redo on my wootzsmelter, after working in the garden.

 

It is my old smelter, made from an 11kg gasbottle, following a design I got from Achim Wirtz here in Germany

it was a bit "nifty" as Niko once said, very narrow for an A1 crucible, so I want it to be bigger in the "heatroom"

which should give me less trouble with the heat for the melts

 

for that I took out some of the casting - had to hammer it out with some effort -

finding that I made the walling very thick, some pieces where thicker than three - four centimeters

out came over 11kg, much more than I thought

the wool is still in good shape, so that can stay, the bottom is still ok and the pipe gives a tangential flame to the bottom of the crucible, there is anough space to use some stands, too

I found an old bottle that will make for the inside, it is big enough to give the space for my crucibles (Achim said: a double-magnum redwine bottle will do the trick, too)

more in the next days

 

[Athan Koumantos 0]

Thanks for sharing the info. I have built my wootz furnace out of an old 40cm diameter metal flowerpot using 5cm of ceramic blanket and about 2cm 1600C castable. It holds an A6 crucible with about 3cm space around it and melts 1.3 kg in about an hour with a 1 1/4 inch burner with 1mm gas orifice at 1.2 bar. Do you think your size would be able to hold an A4 crucible which is about 11.5cm in diameter? (I think my A6 is too much for 1.3 kg) Also how do you construct the cover? I just use some thick firebricks but it seems a bit crude. On the other hand maybe the thermal mass from the bricks keeps the ingot top nice and hot as it solidifies and builds dendrites...

[Athan Koumantos 0]

Two more things. I used a heavy firebrick for the bottom as well. Also, a stand is absolutely imperative. The charge did not melt when I forgot to use it. Also that's when the crucible was almost wrecked by the direct flame (even though its tangential it is still at the same level)

[Jokke 2]

mine is big enough for an A6 now, too, but I tend to use smaller crucibles, since they need less energy

firebrick is not transporting heat well, I recommend using the downer part of an old crucible as a stand

 

pls be free to show some pics here, too, maybe of your burner?

 

here some more pics:

wrapping the bottle with some paper, did not make it much easier to get the concrete in, though

this is how smooth it came out, much better than before

so I heated it up with a burner from a friend of mine, had to close two holes to make it run evenly, but was able to open them up at about 800°C

until then most of the water had damped out and I had an old A6 crucible with some nails in it

then I changed the burner to Achim W's "hellburner" which gave the temp a kick up to 1400°C

let it go for a while

 

although the temp was not high enough to do a melting

next time then...

 

 

[Jokke 2]

... how do you construct the cover? I just use some thick firebricks but it seems a bit crude. On the other hand maybe the thermal mass from the bricks keeps the ingot top nice and hot as it solidifies and builds dendrites...

Hi Athan,

as you could see, I used the cutoff from the gas-bottle as a top. It has a kind of cupola effect. I had gotten the hint to weld some nails into the form, so that the lining of ceramic blanket had a better hold - and then put the cast on it. That works fine

I think something with a better insulating effect would be better as a top, bricks "eat" a lot of energy - but so far I have not made a better "topping", but I am thinking about it...

regards

[Athan Koumantos 0]

Thanks for the invitation to post, Jokke. Here is my setup, a bit crude but it does the job for a 1.3-1.5Kg charge in an A6 crucible.

 

 

Here is the burner setup, it is a blown air burner with a 2 inch blower (I have no idea of the cfm), a simple gas feed with a 1mm tip, and a special flameholder. I usually operate it at a maximum of 1.2 bar, and it easily goes down to 0.2 bar for the final lowering of the temperature.

 

 

The flameholder is a piece of 3/4" pipe inside the tip of the 1 1/4"burner pipe, which is needed to keep a steady flame outside the furnace. I believe it is not needed inside the furnace and will probably remove it.

 

 

Here is the only info I have on the blower.

 

 

Lastly, here is the way we cover the furnace. Again a bit crude, bit I believe the extra thermal mass at the top makes the top of the ingot solidify last and hence avoid shrinkage porosity at the bottom, and build nice dendrites.

 

 

In the near future, we will build a smaller furnace out of a 10Kg gas bottle like yours, for A4 crucibles. I am amazed that you can achieve the needed temperature with a venturi burner. The blower makes everything easier in my experience (like controlling oxidizing vs reducing atmosphere), except using it where there is no electricity (and many times we would like that, as we live in big city and we have to escape to the countryside for our melts). What size is the gas feed tip on Achim Wirtz's hellburner?

 

Thanks for the info and the photos! It always good to know what other makers are using.

 

[Jokke 2]

Hi Athan,

I do have a burner like yours for my bigger red gas forge,

 

the smaller one (5kg gas bottle) works with one of my venturi-systems

in Achims burner was a 1mm gas feed tip that I changed into a 1mm mig-tip, because of its longer straight way for the gas (like rifle barrel, not like pistol) makes the venturi effect a bit stronger.

Achim has been melting with this venturi for years now, needs no electricity, so it is very easy to take along...

 

that is why I started like that, too

but I want to try the blower-type burner in my smelter, too

need to put somekind of connection onto the pipe,since the intake of the smelter is of a smaller diameter than the (I quess 2 inch)pipe of the burner (I did not build it myself, it came with the gasforge, that someone from eastern Germany had to sell, because his neighbours would not let him forge and hammer in the backyard, *bummer*)

 

hope to get to the making of a king these days,

I am going to use the bigger venturi-burner, (the one in the fourth pic) that has a device to blow in extra air (it is a bit like cheating on the venturi)

I will try to show pics then..

best regards