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5. Two-piece shaft collar

This is the two-piece shaft collar. For this we only had to design one half, as the two are identical pieces. When rotated 180 degrees, one component slots into another. This is an adaptation of the typical VEX IQ shaft collar, but it has a square whole in the middle to tightly fit onto axles. It can also be assembled anywhere on the axle, rather than only being able to slide the shaft collar on from the end of an axle. The two-piece is able to move horizontally, allowing the user to easily separate the two pieces and remove from the axle, but cannot move in any other direction, preventing it from falling off the robot. Here we will explain the challenge we faced that drove us to create this component, and how we went about designing it. To design our model, we used the design process that is similar to the Project Lead The Way design process. There are 6 steps to this. 1. Define the problem One problem that we have been consistently struggling with is attaching a shaft collar after having built a mechanism. The first time we encountered this challenge was when we were building the gear train at the back of the robot from which the arm would lift. After having spent days designing, building and perfecting this lift, we realised we had forgotten to put in one of the shaft collars... To put it on, we would have to separate the axle from the rest of the robot and slide on the shaft collar, but it was not such a simple job, with the axle connected to everything else. We then had to take apart and rebuild the whole gear train for just one piece, taking us many long hours to complete. We also made mistakes we had not done previously, making this whole process extremely tedious. This long week of building and rebuilding was all due to forgetting to put in one shaft collar. We needed a solution... 2. Generate concepts We spent an entire lunch break just sketching out ideas that could possibly stop this problem. These sketches were not very detailed, but got the idea across effectively. 3. Develop a solution We then selected our favourite concept idea to become our final design. This was the two-piece shaft collar. We sketched this out and then used Fusion 360 to design a CAD model, as shown in the pictures. As the two halves of this component are identical, the file provided is only one of the two pieces in the two-piece shaft collar. 4. Construct and test prototype Having created a CAD model, we then 3D printed this. The pieces came out perfectly just as we had expected, but there was a problem we had not considered. The inserting part was exactly the same size as the hole, meaning there was no clearance. We could not slot one half into the other. Back to the drawing boards. We made sure the inserting part was slightly smaller than the hole this time so that if could fit. This sketch is shown below. We modified our CAD model, and this is in the rendered images below. We then 3D printed this again, and the pieces slotted together easily! We tested this prototype by using it in multiple areas on our robot, and it worked every time. The component fitted onto the axle and kept beams from moving positions as a shaft collar should do. We had a successful prototype. 5. Evaluate solution We then concluded this design process. We thought about our component and whether it solved the problem. We had brainstormed ideas, come up with a final idea and created a prototype. After the prototype didn't work, we sketched out an edited design and made a CAD model. This prototype worked and our design was successful. The component could be added onto an axle without taking apart the whole mechanism. 6. Present solution We are now doing the final stage of the design process, presenting the solution, by submitting this entry! We are showing where our idea sparked from and the journey to get to the component we have now.