Metal Working|A blog about metal working as a hobby.
Sep
26
Filed Under (Hobbies) by Michael
Kent Klein asked:
Cupola furnaces are the easiest and most economical furnace to work with for the small foundry owner. Hobby metal casters are always on a look out for a cheaper alternative which will provide safety and yield quality results and the cupola furnace delivers all this.
The common appearance of a cupola furnace is that of a smokestack. The furnace can be of nearly any size which is perfect for backyard metal casters. Commonly, the cupola furnace is supported on four legs with a drop bottom to remove any waste from the furnace. This type of furnace does not use a crucible so the metal caster will place the metal to be melted inside of the furnace. The furnace is fitted with a sprout and runner to pour the molten material which is called a taphole. Sometimes cupolas are fitted with a way for slag to be removed. The slag tapholes are located near the back of the cupola a little higher then the other taphole. The refractory used in cupolas are usually brick with the bottom being clay and sand as this is just temporary anyways.
Cupola casting usually involves working with iron and bronze, though other alloys like aluminum can be melted as well.
The common fuel source for cupolas is coke with limestone acting as a flux. Air can be pumped in to increase the burning of the coke. When the coke is hot enough the alloy is introduced in the top of the cupola. Some will place the alloy then fresh coke and then more alloy. The molten alloy will drip through the coke to collect in the well near the taphole. When the level of the molten alloy is high enough, the taphole is opened and then alloy runs into a ladle. When enough has poured the taphole is closed with the use of a refractory plug. Remember, cupola casting does not involve a crucible.
Crucibles are traditionally used to melt the alloy and the collect it in the molten state. With the use of tongs the crucible is carried to the mold and poured. The ladle takes the place of the crucible in this regard. The metal caster pours the molten alloy which is in the ladle into the mold. The most common metal casting process is Sand casting which lends itself well with cupola furnaces.
Cupola furnaces can either be purchased or constructed. Many hobby metal casters prefer to construct their own cupolas finding it difficult to find a furnace to fit their size requirements or their budget. Cupolas have been made from coffee cans large pipes and really just matters on what materials the caster is able to procure. By making your own furnace you will be able to customize it. Many will need a furnace to be small and portable. No one wants to leave a furnace out in the rain, after all. The chances are pretty good that if you are into metal casting then you have some of the technical knowledge needed to make your own cupola furnace. If not, then it is worth a shot just be extremely careful. You may want to find someone in your community that can aid you in your endeavor.
Cupola furnaces are the easiest and most economical furnace to work with for the small foundry owner. Hobby metal casters are always on a look out for a cheaper alternative which will provide safety and yield quality results and the cupola furnace delivers all this.
The common appearance of a cupola furnace is that of a smokestack. The furnace can be of nearly any size which is perfect for backyard metal casters. Commonly, the cupola furnace is supported on four legs with a drop bottom to remove any waste from the furnace. This type of furnace does not use a crucible so the metal caster will place the metal to be melted inside of the furnace. The furnace is fitted with a sprout and runner to pour the molten material which is called a taphole. Sometimes cupolas are fitted with a way for slag to be removed. The slag tapholes are located near the back of the cupola a little higher then the other taphole. The refractory used in cupolas are usually brick with the bottom being clay and sand as this is just temporary anyways.
Cupola casting usually involves working with iron and bronze, though other alloys like aluminum can be melted as well.
The common fuel source for cupolas is coke with limestone acting as a flux. Air can be pumped in to increase the burning of the coke. When the coke is hot enough the alloy is introduced in the top of the cupola. Some will place the alloy then fresh coke and then more alloy. The molten alloy will drip through the coke to collect in the well near the taphole. When the level of the molten alloy is high enough, the taphole is opened and then alloy runs into a ladle. When enough has poured the taphole is closed with the use of a refractory plug. Remember, cupola casting does not involve a crucible.
Crucibles are traditionally used to melt the alloy and the collect it in the molten state. With the use of tongs the crucible is carried to the mold and poured. The ladle takes the place of the crucible in this regard. The metal caster pours the molten alloy which is in the ladle into the mold. The most common metal casting process is Sand casting which lends itself well with cupola furnaces.
Cupola furnaces can either be purchased or constructed. Many hobby metal casters prefer to construct their own cupolas finding it difficult to find a furnace to fit their size requirements or their budget. Cupolas have been made from coffee cans large pipes and really just matters on what materials the caster is able to procure. By making your own furnace you will be able to customize it. Many will need a furnace to be small and portable. No one wants to leave a furnace out in the rain, after all. The chances are pretty good that if you are into metal casting then you have some of the technical knowledge needed to make your own cupola furnace. If not, then it is worth a shot just be extremely careful. You may want to find someone in your community that can aid you in your endeavor.
Aug
07
Filed Under (Art) by Michael
Kent Kelin asked:
Metal casting supplies can run the gamut of cheap to expensive. Home foundries tend to use supplies that are not too costly or that can be found close at hand. After all, home metal casting is usually a hobby and many get into this hobby since they need a cheaper source of parts and pieces that are either far too expensive or just impossible to find. This reason is actually what draws many people to metal casting in the first place. Given this, metal casting supplies used in smaller backyard foundries are generally cheap and made of items that are available in the garage or can be found at home improvement stores. There are several online resources and stores that offer supplies specially made for metal casting and if you have the money and are unable to create your own, it is encouraged that you purchase already made supplies.
The metal casting supplies you will need ultimately depend upon the type of work you plan to do. If you plan to use lost foam casting you will not need any wax and in that same thought you won’t need any foam if you are going to use lost wax casting. The furnace type is also a consideration. Cupola furnaces do not use crucibles. A crucible is where you place the metal which will then pool and collect inside. So it is important to decide what kind of casting process and what kind of furnace that will be used before you rush out to buy supplies.
As for the supplies this will include the fuel source. Fuels sources can range from wood to propane. Metals with a higher melting point will need propane while wood can be used to melt pewter and possibly aluminum. Most home foundries will use propane since it produces a high temperature and is easily available.
Many of the metal casting processes use sand as a way to create molds and help secure those molds during the pouring. The type of sand used does not have to necessarily be specially formulated. Sand has been used in casting since ancient times so it only makes sense that most sand types can be used. Many hobbyists will even use playground sand to meet their needs. Now, there is a special type of sand used in casting called green sand. Green sand packs well and is able to hold its shape far better then common sand. For processes like lost wax you will need to find a healthy supply of wax since many of the steps involve the creation of wax models and molds. The good thing about this process is that the wax can be reused time and time again. Supplies for lost foam can be found in home improvement stores since foam insulation is suitable to use. You will not be able to reuse the foam but luckily, the foam is cheap.
Perhaps the most important casting supply is the metal itself. The metal used in casting varies due to need. Aluminum is a common alloy used in casting for a number of reasons, chief among them is availability. Aluminum soda cans are crushed and melted and proves to a good source of the metal. Many casters will find scrap metal in junk yards which tend to be a good source for brass, bronze, and iron. There are places to buy metals in ingots if you want a purer metal to work with.
Metal casting supplies often dictate what the caster can and can not do. Keep this in mind as you plan your next project as adjustments might be needed to your plan.
Metal casting supplies can run the gamut of cheap to expensive. Home foundries tend to use supplies that are not too costly or that can be found close at hand. After all, home metal casting is usually a hobby and many get into this hobby since they need a cheaper source of parts and pieces that are either far too expensive or just impossible to find. This reason is actually what draws many people to metal casting in the first place. Given this, metal casting supplies used in smaller backyard foundries are generally cheap and made of items that are available in the garage or can be found at home improvement stores. There are several online resources and stores that offer supplies specially made for metal casting and if you have the money and are unable to create your own, it is encouraged that you purchase already made supplies.
The metal casting supplies you will need ultimately depend upon the type of work you plan to do. If you plan to use lost foam casting you will not need any wax and in that same thought you won’t need any foam if you are going to use lost wax casting. The furnace type is also a consideration. Cupola furnaces do not use crucibles. A crucible is where you place the metal which will then pool and collect inside. So it is important to decide what kind of casting process and what kind of furnace that will be used before you rush out to buy supplies.
As for the supplies this will include the fuel source. Fuels sources can range from wood to propane. Metals with a higher melting point will need propane while wood can be used to melt pewter and possibly aluminum. Most home foundries will use propane since it produces a high temperature and is easily available.
Many of the metal casting processes use sand as a way to create molds and help secure those molds during the pouring. The type of sand used does not have to necessarily be specially formulated. Sand has been used in casting since ancient times so it only makes sense that most sand types can be used. Many hobbyists will even use playground sand to meet their needs. Now, there is a special type of sand used in casting called green sand. Green sand packs well and is able to hold its shape far better then common sand. For processes like lost wax you will need to find a healthy supply of wax since many of the steps involve the creation of wax models and molds. The good thing about this process is that the wax can be reused time and time again. Supplies for lost foam can be found in home improvement stores since foam insulation is suitable to use. You will not be able to reuse the foam but luckily, the foam is cheap.
Perhaps the most important casting supply is the metal itself. The metal used in casting varies due to need. Aluminum is a common alloy used in casting for a number of reasons, chief among them is availability. Aluminum soda cans are crushed and melted and proves to a good source of the metal. Many casters will find scrap metal in junk yards which tend to be a good source for brass, bronze, and iron. There are places to buy metals in ingots if you want a purer metal to work with.
Metal casting supplies often dictate what the caster can and can not do. Keep this in mind as you plan your next project as adjustments might be needed to your plan.
