So how to attach wax models to a tree and what do you need to know?
Here is a very informative video on how to attach castings to the wax sprue:
Important to keep in mind:
- The hottest parts are closest to the sprue. This is where your smaller pieces should sit.
- keep the models inside the flask and keep about 2 cm space between flask and the models
- larger items close to the root of the sprue
- small items towards the top where the gravity will also help the metal pour.
- if items are large, or have prottruding elements, add more branches
- it is not advisable to attach large and small objects in the same sprue
- note that smaller items will be harder to fill and require a higher temperature.
Here’s a link to a great read on sprue forming: The sprue system design
Ganoksin also has this article on troubleshooting common problems in investing.
Making a wax sprue tree is not a very complicated process, but it does require some understanding of some very common sense thermal physics.
Also note that you need to think of your tree being upside down when the casting is done.
In the next post I’ll talk about what happens after the sprue has been cast.