Metal casting is a useful skill that has its roots in antiquity. Weapons and sculptures were traditionally created using this method but as the DIY movement gained momentum many modern day casters have found a use for metal casting to make plumbing fixtures, door knobs, and many other items. Today, small foundries can be found in many backyards, garages, and workshops.
In order to make a casting of metal, you will need a furnace capable of melting metal alloys at high temperatures. Usually, individual metal casters will construct their own furnace. There are companies that will sell small scale furnaces but they are often costly. The most common type of casting is called Sand Casting which uses sand or green sand to make the molds where the molten metal will be poured into to form the finished product. The mold is a handmade item placed in a flask which has two parts, a cope and drag. The mold is usually made of sand, but can also be created using other ingredients like latex or even metal. It is in the mold that you will set the pattern to form the mold cavity.
The mold cavity will be an impression of the pattern including the fine details which will then be filled with the molten alloy. Pattern casting is an art form in itself, really, but anyone can create a pattern even if you have no artistic skill what so ever. The pattern is an original which will be cast into metal. Common pattern castings include complex engine parts for models, replicas of Civil War era weapons, sculptures, and even jewelry.
The pattern can be made of any material like clay, wood, and wax. The pattern material really depends on a few factors like the casting method and the availability of the material. If you are able to carve wood then you can use this skill to make patterns. There are some casting methods that call for the patterns to be made of certain materials. An example of this is the Lost Wax Casting Method which will use wax as the pattern.
When creating the mold, you will place the original into the drag of the flask and place more molding material on top forming the cope. When the mold is dry you will carefully remove the pattern revealing an impression in the mold.
If you are creating your own pattern you will need to make it with Contraction allowances in mind. This contraction allowance will compensate for the shrinkage that occurs in many casting processes. In order to take out the pattern without disturbing the mold, draft allowances need to be considered as well. The pattern should have tapered edges to allow for easy removal.
Many who make their own patterns will add sprues, gates, and risers to the pattern so that when castled these items will already be in the mold. These devices will allow the molten metal to find its way into the mold cavity.
If you find it difficult to make your own patterns then you can pay for pattern making services; although many casters in the same situation will just learn how to make patterns to save money. Pattern casting is a valuable skill to have and can be learned rather easily.
