We are back after a few weeks of no posts. What’s up with that? Well, this time we had to create a midterm worthy project based on the 2D drawing that we had made earlier in the semester. Based on that design, we had to incorporate other Mechanical Movements to create a moving physical model of a design of our choice. Initially, I saw my huge gear and thought SUNFLOWER! Unfortunately another classmate was already doing the flower theme and threatened to destroy my project if I copied her idea. Well I was not dumb enough not to heed her warning. I then began drawing on my tablet and the random idea of making a bug came to mind. I began researching different bug body types and came across the Japanese Rhino Beetle. I had a round body, much like my huge gear, and I could make it look cool. It met both requirements that I needed, so I began to draw. As evident in the picture below, the Rhino bug would be able to flap its wings as the gear spun and there would be other linear and rotational movements behind the body. Labeled are the various mechanical movements that I planed to incorporate.
Idea Drawing
After coming up with the idea, I instantly began drawing up the parts in Illustrator. I have gotten into the habit of just making all my parts from scratch, so this project was no different. I began with the old 2D drawing file of the gear mechanism and incorporated all the teeth of the gears in to one shape. Previously all the teeth had to be glued onto the shape, so to make my life easier, the gear and teeth were combined into a more manageable shape.
I then began to create the support structures for the gear to sit on. For this I mostly just measured how tall I wanted to gear to sit and made the structures. I had set a height limit to myself of 16″ so I had to keep that in mind every time I made structural changes. With the basic structure done, I decided to test out the wing flapping function before actually implementing it in to my design. I created another test structure that would focus on the position of the wings and the mechanism that would make them flap. To do this I began with the huge gear and positioned the attachment points of the wings as close as I could without touching the gear. I then created the wing shape and made sure that it would not interfere with the support structure. At this point I also began to draw the mechanism that would make the wings go up and down. For this I used
Bearing
93. It would travel linearly and move the wings out and in as it traveled. The connection between the machine and the wings was also established and then I went to cutting on cardboard. Once I had seen that the wings would roughly move, then I proceeded to cut the designs I had out of wood. This would be V1 of the project.
V1/V2
The first thing that I tested was the gear movement though the use of the spade gear that comes with Machine 205 (which is what the base for the project was). After a bit of testing, it turned out that the sharp gear teeth were stabbing the spade gear a bit and getting stuck in the process. I then went to each gear tooth and rounded the corners. After more testing, the rounding of the corners proved to be effective. Version 1 however was not great. The wood that I had was a bit bent, so the gears would cross planes with the other tooth and get stuck. For Version 2, I cut out a .043″ acrylic spacer and added that in between the gears and the spade gears. This was much better in terms of not crossing planes and the gear moved decently (after rounding the corners again).
Version 3 was next and this time I would test more of the wings. I cut out the wing and the post as before and began incorporating then. Almost instanly I discovered an error in my design. There was a .75″ rod that was going to go though both of the structures and through the huge gear. Additionally the linear motion machine 93 would move behind it. Well, the rod could not go all the way though both of the support structures and be fastened, because then the machine 93 would hit the rod every time it would move. I needed the rod to go at least .193″ (the width of the wood I was using) to be able to add a glued washer to prevent the rod from coming out. This design would not work the way I had it designed, so it was back to the drawing board.
Impossible Move
I then began formulating the idea of using a bearing of some sort. I knew that I could not use a normal bearing, so I decided to draw my own into the design. This bearing would rid inside a rig cut out of the back support structure and help the gear stay in a perpendicular path to the structure without having to be attached to the back support structure in any way. Additionally, though testing V3, I discovered that the one sided wooden version of Machine 93 would bind with the wood post that it was supposed to rid along. I decided to then cut out both the bearing and the Machine 93 out of .25″ acrylic so that there would be less friction in the system.
Bearing and Modified Machine 93
After doing this, Version 4 came to life. I cut out all the parts that had a function and glued everything together. With everything on the structure, I would tell that most of the geometry was correct, but there were still some binding issues. For this version I did remember to round the teeth of the huge gear and that helped, but the wood that I used was even more bent, so I discovered that I needed to go with a thicker piece of spacer in between the gears. This meant that I also needed a thicker spacer for the space gears so that they could interact in the right planes. To get the two gears aligned correctly, I cut out two small holes in the spade gears and two spacers that also had the same holes and then stuck a rod in each of the holes. This would line up all the holes and have the gears perfectly aligned. After testing Version 4, there were still some binding issues, but I decided to go ahead and cut out Version 5 with finalized parts.
V4
For Version 5, I decided to do a V5.1 and V5.2. Version 5.1 would have the support structure be made out of wood and V5.2 would have the structure be made out of acrylic. I figured that one would bind less than the other. Unfortunately at this point I lost some files so I had to redraw some of my design. As version 5.1 was made I knew that the wooden structure would be best. I then went on to cut the final base to look like a mountain and added some aesthetic appeals to it in the form of grass. I stained many parts in black to represent the parts of the lady bug approach that I decided to go with in the end and spray painted the wood according. As the wings flap it reveals a copper paper that I had laser cut to mesh perfectly with the support structure and the back of the wings was a brown paper that was also laser cut to give it some more uniqueness. I added a turn wheel instead of a lever because I felt that it would be easier to manage and get a better turn out of it.
As you can see, all the version helped lead me to the final version that will be submitted. The prototyping phase of any project is invaluable to the success of any project.
Versions
In the end I was very happy with the project I created and although it took a few sharp turn, the end product is something that I really appreciate.
One thing that I wish I would have done is incorporated the bearings that I bought. I did not have enough time to add this to the design and would have needed another weekend to iron out all of the kinks. In the end one part not added is ok.
In terms of cost. The material I used was scraps for everything except the final project. With that in mind I would say that I used about 3 full sheets of plywood total with would amount to ~20$. The acrylic I used was also scrap but would amount to ~10$. In terms of labor, we had three weeks to work on the project. Total hours worked was along the lines of 15 to 20 hours. That means that at the low of 10$ an hour it would be 200$. That brings the total to 230$. Since the end product is done well I would add another 50$ to it to compensate for the added effort to the aesthetic (which I would have done anyways). That brings the total cost of this project to 280$.
Prototype_Wood_Parts_V4.1-24dt0zt
Parts_For_Acrylic_Posts_V4-2jqavyk
