These discs provide the shape for the cylinder. The holes in the top disc are to provide a handel to remove it when done.
And before your very eyes, a cylinder. I formed a 1" or so bend down one edge of the sheet of aluminium. This goes into the slot of each disc and the aluminium is taped to the discs to stop it popping out. The sheet is then rolled around the discs to form a cylinder. I used some string and a couple of screwdrivers as a Spanish windlass to hold it all together while I taped all the seams.
This is placed in the centre of the bucket and spacers are used to keep it in the middle. A hole is drilled at the bottom for the air blast shown in the picture. Next I mixed up half a bucket of refactory which I purchased from a local firm that repairs furnaces. ( Bought 3 bags and have used half of 1 so far. Anyone want to build a furnace ?)
The spacers are raised as the refactory is packed down.. The refactory must be rammed into the gap under the spacers to fill the void they leave as they are raised. This can be a bit of a messy job and a mat of some sort should be used. (Bigger than this piece of cardboard which I used).
Filled to the top. Notice the tube coming out of the air hole at the bottom. This is the "hoover" hose used to provide the air blast. ( Note: other brands suck just as much as a hoover....... )
I tried to take the wooden former out before the refactory had gone off but managed to jam it back in somehow.
I left the furnace to dry out overnight, then lit it with a bit of newspaper and a bit of kindling. I got a bit of a fire going and water started to bubble up between the bucket and the refactory. When this stopped I added charcoal, left it for about an hour then turned on the air jet for about 5 minutes. Being impatient, I turned off the airjet and placed my crucible in the furnace with a bit of scrap aluminium. When the crucible started to glow red I put the air jet back on and had the scrap melted in no time .
I have still to make the lid. This may be done today or tomorrow. (19-05-06 or 20-05-06). Being imp Charcoal Foundryatient to use the furnace I have been using some bricks as a lid instead.
Pictures of the furnace in operation to come.
Check out my castings so far......
