Construction: Unfortunately I didn't take a lot of pictures during construction, but basically the shell is made of 16" ID pipe, and I used a piece of 8" ID pipe for the inner mold. You're probably wondering how I got that thing out once the refractory dried eh? Well, it came out quite easy -in 2 halves. Before I put it in I cut the 8" pipe in half, then welded tabs on the inside and put a 1/4" thick strip in between the 2 halves and bolted it back together. The strips were flush with the outside of the pipe, and when I cut the pipe with the torch I took out a 1/4" so when I bolted it back together it would be round. I just simply removed the bolts and pulled the strips out and the 2 halves colapse and you just pull out the 2 halves. I'll have some pictures of the inner mold soon so you can see how it was constructed.

On the left is a picture of the inside after the refractory was casted. I used a commercial castable refractory 1 because it was available, and 2 it lasts a long time. I've seen furnaces that have been used for 30 years with the same refractory and are still working. This refractory is good for 3500 degrees. I spent a week slowly heating the refractory to drive out the water. If it is heated too quickly during the curing stage it will explode, so it is important to heat it slowly, even though it looks dry it still contains a lot of moisture. The lid is not made of refractory but is some kind of insulating board the casting industry uses on their furnaces, i'm not really sure what it's made of but it's light weight and it works great, you can touch the top when the furnace is up to full temperature and it's just warm. The picture to the right is the completed furnace.

Here's some pictures of the furnace in operation. These were taken just after the refractory was finished curing and yes it was still cold when I took these pictures, i'll have some more pictures of the furnace with the crucible full of molten metal. I have had my steel crucible white hot! The one in the picture was one I had just finished welding. It is a 4" steel crucible made from 4" ID pipe that is a 1/4" thick with a 1/4" bottom. I have added a pour spout since this picture. My crucibles are constructed by cutting out the bottom to fit on inside of the pipe. The plate is fitted 1/4" from the bottom and welded on the inside bottom and on the outside bottom. This is a fairly descent sized furnace, that 4" crucible looks small in there. I am going to make a 6" crucible, but this furnace should be able to fit possible a #10 crucible. I may get a clay graphite crucible for use with metals that melt a higher temperatures than aluminum which has a melting point of 660.2°C and a boiling point of 2,467°C, it's atomic weight is 26.98