Designing the catapult
This catapult design has a unique operation as the arm almost rotates a full 360 degrees before hitting the stopper and releasing the squash ball, similar to an underarm throw.
Building the catapult
Building the catapult
Quick pre-assembly testing
The cup was initially going to be rapid prototyped. However, this shape would not secure the ball properly when it is rotating around the axis before the release impact. A new more simple and cheap cup was redesigned and manufactured by vacuum forming around a table tennis ball, as it was approximately the same size as a squash ball, so it would hold the squash ball more securely.
Instead of using a PVC tube, with a variable profile, a cylindrical aluminum tube was used instead; making sure it can withstand the force of the elastics on it in loading position. Another tube was then welded onto the axel to create a slot for the arm, which also provided an easy way to replace it.
The arm was originally designed as a beam, so it can withstand the impact force on release better. However we changed the design of the arm to a cylindrical aluminum bar as this would be easier to secure, and replace if necessary, to the axel. After testing, the cylindrical bar also proved to be strong enough to withstand the impact force.
The release trigger was improved from the initial design by increasing its surface area in contact with the bar as well as altering its movement to be against the plane of the arm’s movement. This would increase safety and security when the device has been loaded.
The finished product
Testing
Max Distance 47.3m
Max Distance 47.3m
Post manufacturing 3D model and animations
