Rafe Neathery and Jorge Quintero
For our final project, we decided to make a governor mechanism out of wood. This was inspired by those carnival rides where riders sit in swings that fly out to the side when the ride spins. We thought this would be fun, since you could spin the model fast and watch the weights on the arms fly out. We decided to go with a space theme and make the weights/swings little rocket ships.
We thought it would be fun to make it also pivot around like the one pictures above, but that would add more complexity than we were prepared to deal with. We decided to have a simple design, where the user would crank a large gear that connected to a smaller gear. The smaller gear would have our tower, and on the top we would have a plate with 6 pivoting rockets.
Prototyping
We felt confident in our concept, but wanted to test two key mechanical functions: The rotating arm and the gears. We selected a gear ratio of 5:2 and used an online gear generator to make some files we could use. However, the gears we cut didn’t mesh quite right, and we decided to use a different generator recommended by Dr. Wettergreen. This time we cut a base plate as well, and inserted some dowels to act as axles for the gears. They ran smooth enough, and we figured they would get better once we sanded and greased them. We also designed the arm subassembly in solidworks and cut the pieces. It also worked fine, though it was clear we would have to nail the thickness of our axle to get a smooth rotation. With this prototype we also decided to fix the rockets on the end, so it would look like they were taking off (and to reduce complexity).
Gear Prototype video:
IMG_8377
Design
We decided to design the full mechanism in CAD since we were comfortable with the software and could add some confidence to our designs. We prioritized stability in the design because we were worried about the tower wobbling or even falling over. We also looked for ways to increase the long term reliability since many of the mechanisms like this in the past were now broken. These priorities led us to add bearings and spacers to reduce friction, thick plates and gears to increase stability, and a ring around the tower that kept it in place. Though the ring adds some friction, it would end up being absolutely necessary.
Manufacturing
Most of the parts we made were laser cut. Some of them took a few tries, and some took some work to cut out when the laser didn’t go all the way through. Eventually though we got everything made. The axles were made from wooden dowels and we just chopped those in the woodshop. Finally the rockets were cut on the waterjet out of aluminum.
Assembly
Naturally, barely anything fit together perfectly. It took a lot of sanding to get it all together and moving. It took a lot more wood glue as well. The big gears we glued together were very slightly offset, which caused a lot of issues with meshing. Nothing another hour and a half of sanding can’t fix. We assembled parts that had the same colors, and then painted or stained them together. Afterwards we lightly sanded them to even the paint and applied a clear coat. Finally it all went together. We cut some decorative vinyl pieces and added them to the base. It worked surprisingly well, and spun way faster than we expected.
Video of the project moving
Debrief
We are pretty excited with how it turned out. Some of the coloring is a little off, but it’s still vibrant and exciting. The spinning is pretty smooth, though it does catch occasionally. Sometimes the rockets get caught too, and don’t fall down on their own afterwards. Still the project is definitely a success.
The cost estimate is gonna be tricky, since we didn’t use a lot of material but spent a lot of time.
Material:
2 wooden sheets = $28.82
1 aluminum sheet = $25.54
Wooden Dowels = ~$5
Spray Paint/Stain = ~$10
Sandpaper = $~3
Wood Glue = ~$2
Labor:
~30-40 Hours
Other:
Power/Machine Maintenance/ Lab Assistant help = ~$10
Total: ~$85 plus 30-40 hours of labor.
Our Slide Deck can be found here.
