Project Overview
Additive manufacturing processes have the benefit of creating assemblies with moving components that require no post-manufacturing assembly. The printing of these assemblies can be more difficult than just creating a single component because the print direction – or layering – of one component has to correspond with that of another. Optimization of print direction to deal with the stresses seen by the assembly is more of a compromise than a combination of ideal directions. To show the iteration of the construction of a multi-component assembly using additive manufacturing technologies, a rubber band gun will be optimized and created with just one print.
Preliminary Design
Our preliminary design is a three component assembly consisting of a trigger, wheel, and frame. The trigger will be responsible for allowing a rubber band to release after it is pulled, while the wheel holds all rubber bands in tension from the muzzle.The frame will hold both of these components in an ergonomic package. All parts will be designed so they can be supported with dissolving structures.
Manufacturing Considerations
When manufacturing the rubber band gun, the first consideration that will have to be made is the ability for parts to free move while fitting together well. Small clearances may allow for a smoother operation up to a point, but may cause parts to print together if too small.
Another point that must be considered is the print direction and geometry of the tabs surrounding the wheel of the gun. These tabs are responsible for holding the rubber band, so they will have a force acting on them – leading to a high likelihood of failure in shear. If it is possible, it may be advantageous to print the gun sitting flat on the table so the print direction is perpendicular to the force of the rubber band.
Proposed Analysis
For our first iteration we will print the wheel to analyze the force it can withstand and if it is strong enough to support the rubber bands. Our second print we will bring the moving parts inside the gun to check if they run smoothly when printed as one part. Because our goal is to print the rubber band gun and all of its moving parts in one print we will need to use melt dissolving supports. Our third print will be of the entire gun once we have perfected the smaller parts.