In any assembly that involves mechanical interaction between components, defining the right tolerances according to the model material and the manufacturing process is a key factor for success. Designing a part for rapid prototyping is not an exception.
There are two methods of prototyping assemblies with a 3D printer – either print individual components to be assembled later, or print the whole assembly in one single print job. The method you choose will depend on the type of assembly you require…
Individual components for subsequent assembly
Use this method for the following circumstances:
- If you don’t have a multi material printer (such as an Objet500 Connex), and need to use different materials due to mechanical properties or colour specifications.
- When, due to the complexity of the assembly, the support removal is a challenging process (intricate channels or hard to reach inner gaps).
A tolerance of 0.3 mm (12 thou) between touching surfaces will let you assemble the components once they are finished and allow the parts to move and interact freely.
3D printing the assembly in one transaction
This is the preferred method if you don’t need to use different materials / colours in a moving model and assembly is not required; this method is also a time saver.
You will need to allow a 0.3 mm (12 thou) tolerance between touching surfaces to allow the support material to fill the gaps between parts and prevent the moving components to be bonded together.
Take a look at the example, this was created in a single print job without the need for assembly and the individual gears move as required!