II) Design Process

The design process of this mechanism was one that was constantly being improved on and changed as it was coming together.

The first step in my design process was figuring out the dimensions necessary for each of the links in order to allow for a full 360-degree rotation to occur for the input link. In order to do so, I used SolidWorks sketch tool, as shown below in Figure 1. By adding some dimensions to the links as well as making the construction line serving as the runway of the slider a fixed-line, I was able to accurately represent the 5 bar slotted mechanism and its movement. To make sure that the dimensions chosen would allow the input link to rotate through a full rotation, I would just select the link and move it around in a circle. The dimensions shown in Figure 1 were the dimensions I chose that allowed for the mechanism to move in the way I was wanting it to. 

Figure 1. Solidworks Sketch with Dimensions

After deciding on the dimensions of my mechanism, the next step in my design process was to decide what material to make it out of. While at first I thought of using the 3D printers to create it, I quickly realized how much more time effective and precise using a laser cutter would be. Additionally, I find that wood is a lot more sturdy and the use of the laser cutter would save me a lot of time trying to figure out the tolerance of the 3D printer. Since only 1/8" and 1/4" plywood is offered at Texas Inventionworks, and since I was looking to make my mechanism as sturdy as possible, I decided to go for the 1/4" plywood. 

As far as designing the individual links of the mechanism, I decided to steer away from creating a normal link as my input link and instead built a flywheel. The reasoning behind the flywheel was that it would create a more stable input 'link' than the traditional link would, especially since all of the weight of the mechanism would be carried on it, and I felt it was necessary to make this as stable as possible. Additionally, this would allow for the mechanism to not slant down as much due to the weight of the links and joints. For the joints, I felt that using bolts, nuts, and washers would be beneficial as it would allow for the links to rotate on one another smoothly, especially if using washers to reduce the amount of friction between them, while also allowing me to easily add nuts and washers in areas where I needed a spacer or some additional support. I ended up settling for 1/4 in bolts to minimize the size of the joints and the size of the mechanism as a whole. 

From my experience, figuring out the slider was the most challenging. My initial idea was to create a runway out of acrylic that would fit the wooden slider and allow for it to move in there with less friction than a wooden slider would create; however, I quickly realized I would need something that would allow for the movement to be much smoother than that would. I thought that the use of undermount drawer slides would be a great solution as this could be attached to the grounded board and have the slider move up and down without experiencing much friction. Based on my calculations and the SolidWorks sketch shown in Figure 1, I believed that a 12 in cabinet slider would allow for the full motion of the slider; however, when mounting the mechanism, it was clear that I needed a longer slider, which is why I ended up getting a 6 in longer, 18 in long slider just to make sure I was not going to run in any other problem with it restricting the motion of the slider. The 18 in slider seemed to work perfectly and was drilled into the board for stability and to ensure that the run of the slider was entirely vertical. 

The last step for my design process was to measure the distances of the grounded links and cut the wholes in the 1/4" plywood I was making my grounded board from. There were only two holes that had to be made, one for the center of the flywheel and another for the grounded pin that ran inside the slotted link. I also cut the board of wood I bought to be a smaller size but left enough room in case I would need a longer slider, which ended up being the case.