This week's challenge is to build a mechanism that converts rotational motion to some other kind of motion. It will be constructed out of Delrin sheet and teflon rods.
My partner and I were inspired by a motion module that our professors showed us in class. By rotating a teflon rod in this module, another part of the mechanism moves up and down. It's a relatively simple motion, so we wanted to elaborate this design by adding another element and increasing its size. In this module only the rod moves up and down and we wanted something else to move as a result of that. So we came up with this idea of a drawbridge. As the rod moves upwards, it would push up two separate plastic boards.
Here is a sketch of our design:
In fact, our design is very similar to the motion module shown by the professors. One our concerns was how to prevent the boards of the "drawbridge" from falling down as the rod would push them up. We first considered putting in place a rod that would stop the board from falling, but that would just add to the complexity of the module. Our other idea was to make a hole in one of the plastic boards where a piece a plastic would prevent it from falling off completely. Here is a sketch of that:
After coming up with a general idea we made a foam board design with dowel rods. This really helped us realize which dimensions we had to adjust in order for the module to work efficiently. It also made us pay attention to how we would attach the plastic boards together. Here's a picture of our foam model:
As you can see, the model doesn't function very well. The sides of the model are too small, therefore it didn't give enough room for the rotating circle to push up the vertical rod. So we recalculated the dimensions of the model and the location of where the rod should be. Making this model really showed us that careful, precise measurements had to be made. Here is a close up of the "draw bridge":
For the "draw bridge", we have to make sure that the opening on the board to be long enough so that it would give it enough freedom to move, without falling of course.
After building the foam model and taking in consideration all the adjustments we had to make, we started transferring our design unto SolidWorks. The nice thing about SolidWorks is that you can make changes very and visualize your design very easily. However, since we are still learning how to use SolidWorks, it did take us a lot of time to construct our design. We learned how to create an assembly and it was a bit tricky to connect the pieces together. In order to do that, you have to create relationships between two pieces. For example, you can make certain edges coincide or make two faces parallel. We figured out that there is usually a specific order when forming these relationships and in doing so, it allows you to move a piece in a certain way. After making the general structure, Alex and I got the hang of making assemblies and now all we had to include was the rods, bushings and "drawbridges". Here is what we ended up with at the end of the day:
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