New and hopefully improved

As I mentioned last week, I had a vague idea of where to go next with the forge and distracted myself with other projects, like the bakso cart, and some bamboo swords. On Monday I had the idea to bury the forge underground, so less heat would escape, and also so that it would be more permanent. I started to dig a hole. Two days later, on Wednesday, I sat with Pak Jason and showed him my design and shared with him my ideas.

My basic design idea was for the entire forge, except for one layer of bricks, to be underground, and for there to be a chute that would let the fuel in. Jason looked at my design for a little bit, and gave some good advice on how to improve on it.

He told me to make the forge a little smaller at the top, so the heat would be more concentrated on the crucible, and so it wouldn’t be shooting out sparks. This design, although pretty good, had one problem, which was that the hole would have to be pretty deep, and hard to dig out, so while I was building it, Jason came over again to help out.

He showed me this neat technique that allows you to make squares any size with bricks, which was very important to the final design

I still liked the idea of the forge being in the ground, so I kept the small hole I had dug earlier

I used it to make the bottom layer very sturdy and permanent, and laid the ground with bricks, so the sand at the bottom could be easily replaced and not get mixed with the dirt

After came the grate, so the charcoal had a place to go

The next layer is just four bricks in the pattern that lets me control my square size, and im starting with a large square

The next layer is a slightly smaller square, alternating the brick placement

The squares are slowly getting smaller, and on the far side of the forge, there is a little staircase beginning, which is an important part of the design

On this layer, the bricks break “formation” to make the gap much smaller so the heat is more concentrated, and so the crucible can fit in better

The top layer is just large enough to catch the crucible on its handle, so it doesn't fall down, and almost all of the heat is concentrated on the bottom of the crucible, so it is much more efficient in using heat

Something that seems like it is missing in this design is how to put in more charcoal, and the only way to put it in is if you remove the far brick(the one which is half grey) and pour it in that way. The small staircase that I mentioned earlier acts as a ramp for the charcoal to reach the bottom.

At the bottom is a small hole that I dug out along with a gap in the bricks for the air to get into

Because of the ramp that the charcoal uses, the forge is weakened on one side, and could easily break, so I put some extra bricks to help stabilize it

Here are some profile shots of the crucible made out of iron which I got made for me for 100,000 IDR, and hopefully it is a better crucible than a cut in half water bottle that I used last time

I also made a proper lid for the crucible instead of a brick

Previously we used a plastic bowl to put the charcoal in, but I made this little chute from aluminum leftover from the bakso cart project, attached to old tires. Using this to pour the charcoal in should be more efficient and more permanent

The is what the forge looks like when everything is on

Overall, I think the new design is much better, and I expect it to be much more efficient with heat, as well as to use less fuel. The original design had a larger frame, and because of this a lot of heat would escape from the forge, causing the need for more fuel, therefore making it take longer to heat up the forge. But with the new design, the frame gets gradually smaller, causing there to be less space for heat to escape from the forge, which will focus the heat in a smaller area, causing the crucible to heat up quicker. The heat will also all be focused on the bottom, which will melt cans much faster. Another thing that the new design should be better at it is trapping the heat within the forge. The original design’s biggest flaw in my opinion is the brick placement, and how the corners that two bricks would make would often have open areas, allowing a lot of heat to escape. The new design doesn’t have the same brick placement, and the new brick placement doesn’t have the same issue with the corners, but at the bottom of the forge where the squares are large and the bricks don’t overlap as much, I’m worried they might push apart from the pressure and allow the heat to escape that way. This doesn’t worry me that much, though, because heat travels upward, and hopefully the heat will just escape instead of building up as much pressure at the bottom. However, at the same time on the original design, we had to put bricks to block the escaping heat at the bottom of the forge. Hopefully this won’t be an issue in the new design, but I’m sure it will be somewhat of a problem. If it does happen, I can always do what I did last time, and put a bunch of bricks around the bottom to block the escaping heat.

The crucible that I got is a much better step up compared to the cut in half water bottle that I used previously, and I hope it will last a while. The handle that I added will be great for pouring castes, and make it much easier. My only concern about the handle is that it is hollow and made out of a much weaker metal, so I’m worried that it might melt off of the main part of the crucible. Another thing that worries me about the crucible is the welding. The highest melting point of melding soudre I could find is 450°C, and the melting point of aluminum is 660.3°C. This is concerning because the welding might get too loose under the heat, and the bottom of the crucible might fall off, or the welding the keeps the handle on will melt, and the crucible will fall into the forge. Hopefully none of this happens, and if it does, then I just have to figure out how to get around this, which should be pretty fun.