Medieval times brought us so many great engineering machines which helped brave knights break down the wall of their enemies. Many of these mechanisms are still used today and are being developed for new technologies. So, we took a trip down memory lane and built a small desktop catapult and used some modern technologies to 3D print it. This is also great for annoying your coworkers by shooting little paper balls around the office.
To build the catapult, we use a top-down design technique, this allowed us to change the model as we designed the catapult. This technique is great if you don’t have a full idea of the design direction you are taking.
We built the basic body using basic SOLIDWORKS techniques. Once the main body was complete, we added the axis where the bucket will pivot on; we created the basic shape of the bucket for reference. We built the coil spring, this will be what drives the catapult. To build the coil, we drew a reference circle. Then made it into a spiral using the Helix/Spiral feature. This gave us our reference lines to make the body of the spring.
Once created the spring, we finished the bucket; this is where the projectiles will take place. This shows the best example to where top-down design technique was useful to design the shape and edit it within view of the body. Once the bucket was designed, we used the Move Body feature to move it in the starting position. This lined our catapult model up to create the pins that attach the bucket to the end of the springs.
For printing the design, all the parts were printed at 0.2mm layer height and 15% infill except for the springs, those were printed at 0.2mm layer height and 0% infill. This allowed each layer to be uniform and springing properties.
Building the printed catapult was super easy. We placed the pin for the bucket and alighted it with a screw driver. Then, we put the coil springs in place and aligned the pins for the coils and that’s it! It’s assembled and ready to take siege of your neighbor’s cubicle.
We will continue to develop new technologies using SOLIDWORK to create designs, test them with simulations and then bring them to life with technology.
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