| Cupola furnaces are the easiest and most | | | | will drip through the coke to collect in the well |
| economical furnace to work with for the small | | | | near the taphole. When the level of the molten |
| foundry owner. Hobby metal casters are always | | | | alloy is high enough, the taphole is opened and |
| on a look out for a cheaper alternative which will | | | | then alloy runs into a ladle. When enough has |
| provide safety and yield quality results and the | | | | poured the taphole is closed with the use of a |
| cupola furnace delivers all this. | | | | refractory plug. Remember, cupola casting does |
| The common appearance of a cupola furnace is | | | | not involve a crucible. |
| that of a smokestack. The furnace can be of | | | | Crucibles are traditionally used to melt the alloy |
| nearly any size which is perfect for backyard | | | | and the collect it in the molten state. With the use |
| metal casters. Commonly, the cupola furnace is | | | | of tongs the crucible is carried to the mold and |
| supported on four legs with a drop bottom to | | | | poured. The ladle takes the place of the crucible in |
| remove any waste from the furnace. This type | | | | this regard. The metal caster pours the molten |
| of furnace does not use a crucible so the metal | | | | alloy which is in the ladle into the mold. The most |
| caster will place the metal to be melted inside of | | | | common metal casting process is Sand casting |
| the furnace. The furnace is fitted with a sprout | | | | which lends itself well with cupola furnaces. |
| and runner to pour the molten material which is | | | | Cupola furnaces can either be purchased or |
| called a taphole. Sometimes cupolas are fitted with | | | | constructed. Many hobby metal casters prefer to |
| a way for slag to be removed. The slag tapholes | | | | construct their own cupolas finding it difficult to |
| are located near the back of the cupola a little | | | | find a furnace to fit their size requirements or |
| higher then the other taphole. The refractory | | | | their budget. Cupolas have been made from |
| used in cupolas are usually brick with the bottom | | | | coffee cans large pipes and really just matters on |
| being clay and sand as this is just temporary | | | | what materials the caster is able to procure. By |
| anyways. | | | | making your own furnace you will be able to |
| Cupola casting usually involves working with iron | | | | customize it. Many will need a furnace to be small |
| and bronze, though other alloys like aluminum can | | | | and portable. No one wants to leave a furnace |
| be melted as well. | | | | out in the rain, after all. The chances are pretty |
| The common fuel source for cupolas is coke with | | | | good that if you are into metal casting then you |
| limestone acting as a flux. Air can be pumped in | | | | have some of the technical knowledge needed to |
| to increase the burning of the coke. When the | | | | make your own cupola furnace. If not, then it is |
| coke is hot enough the alloy is introduced in the | | | | worth a shot just be extremely careful. You may |
| top of the cupola. Some will place the alloy then | | | | want to find someone in your community that |
| fresh coke and then more alloy. The molten alloy | | | | can aid you in your endeavor. |