Introduction
For our ENGI 210 midterm, we were challenged to create a physical mechanical model based on one of the 507 Mechanical Movements. After considering several types of different mechanical models such as a ferris wheel and marble track, we settled on making a Carousel driven by Mechanical Movement #24, a basic two gear crankshaft mechanism, using it’s rotational motion to spin dowels over groves to get a reciprocating motion for the horses. Our goal was to complete the beginner level (Due to time constraints) for this project and apply this simple two spear gear principle to build a carousel, a amusement ride known for its rhythmic up and down motion.
Brainstorming/GATE 1 PROTOTYPE
The first step in project was brainstorming ideas for how to adapt a two spur gear motion to fit our carousel. Initially we thought that using a bevel gear like Mechanical Movement #26 would best accomplish this as we had seen some successful models using similar designs like this online. To fully flesh out our ideas we drew them out and set out some basic dimensions. Using gear generator we created the gears for our model and designed the rest of the pieces using Inkscape for our first prototype. When these were completed we then laser cut the Inkscape svgs and put together our gate 2 prototype. There was a decent bit of iteration that had to be done with the Inkscape designs since a lot of the sizings for the holes were not accurate enough for tight fits, but we were able to get by and produce the prototype below.
Gate 2 Prototype
However throughout our initial prototyping progress we did some some struggles with this due to problems connecting the crank housing to the carousel since there was so little area to do so, but we were optimistic we could find a solution to this problem and get the bevel gear functioning in our next prototype. Unfortunately, the advising team suggested to attempt a simpler design because of previous teams experiences with similar mechanical models, so we ended up dropping this design for a simpler two connecting spur gear motion like Mechanical Movement #24. Thankfully though, this change did not require us to have to make large scale redesigns from our original prototype.
For the redesign we sketched new drawings, defined new our new dimensions, and drew up some new svgs drawings for the model based on more accurate measurements with our selected dowels. This new model was similar to our past just with some new adjustments. It now included a box base to house the two spur gears, a circular plate on top of the box for the groves to be placed on, two rotating upper plates, four dowels with space to move up and down for the reciprocal motion, and a hand crank. Once these changes were completed we were then advised to make our gate 3 prototype using cardboard, so that is where we shifted our focus to. We also designed new groves so that we could achieve a smoother up and down motion for the horses. For prototyping all of these designs we use the two epilog laser cutters, just depending on which ones were in use or not.
Gate 3 Prototype
After all of the prototyping and iteration was completed for our gate 3 prototype we were fairly happy with the results we had gotten. The spur gears were in good contact with each other and the carousel spun when the crank was moved. There was also good alignment between the circular platforms, dowels, and box that allowed for free motion. We did have some issues when we tried to get the up and down motion because of the friction between the bottom of the dowels and the grooves, so we made more efforts to sand them and the dowels down to reduce that. We also did have some issues with the two central dowels moving when spinning the carousel, which moved the gears out of contact with each other. Thankfully after speaking with the advising team, we were able to come up with some solutions to these problems that we’ll touch on later when explaining our final mechanical model.
FINAL Mechanical model Steps
Now that we had completed a fully functioning gate 3 prototype we were confident tags we could move onto the next step of making our final mechanical model. We applied the same designs as our previous cardboard model, with some slight sizing adjustments for the boxes and gears to make a more compact design. A small window was added in one of the sides of the box to allow for the mechanical movement top be seen. We then laser cut the pieces and assembled the box and carousel together. The horses for the carousel were cut using the laser cutter as well, and red and blue vinyl designs were produced using the vinyl cutter to be set over them. We additionally sanded the surface of the groves and applied beeswax to them and the bottom of the dowels to make them smoother. A small smoothened wooden knob was also made to go on top of the crank so that moving it would be easier. To improve the look of the box and carousel we applied a dark wood stain before adding some of the final pieces. Before this, hot glue was use to connect the upper two plates to the central dowel to ensure they we not slip during movement.
FINAL Mechanical model
To complete our final model we laser cut/etched our name plate and attached the wooden horses to the dowels, grooves to the bottom circular plate, and name plate to the box using hot glue. Once assembled, the carousel spun pretty smoothly, and the horses moved up and down in sync with the rotation just as we intended.
FINAL Mechanical model Video
Tools/Techniques Used
Inkscape, Adobe Illustrator, Cricut Design Space
Epilog Laser cutters
Wood stain
Beeswax
Vertical Bandsaw
Drill Press
Vinyl Cutter
File, sanding paper, orbital sander
Lessons Learned & Future Improvements
While in the end we were both happy that our mechanical model was completed and that it functioned properly, we both felt that the large amount of time we spent working on this project did not accurately reflect the final product as there is a lot we would like to improve but found hard to do, due to time. However this project did reinforce our understanding of mechanical movements, precision assembly, and laser cutting. If we were to improve our design, we would
Tune the box svg design to better account for laser kerf so that the finger joints of our box fit tightly
Use metal bearings to more guide our central dowels in a smoother and more direct motion.
Optimized our gears for motion smoothness.
Added more structural designs to the rest of our model to look nicer
Clean up our model with further sanding and finishing techniques
Cost analysis
Wood (3 1/4″ 3x3ft) & Cardboard (2 1/8″ 3x3ft) Sheets : $38
Wooden Dowels: $10
Hot Glue Gun and Glue: $4
Beeswax (1 Bottle): $10
Wood Stain (1 Can): $13
Vinyl (1 1x1ft Sheet): $3
Rented Epilog Laser Cutting Time (3 hours): $30
Rented General Machine Shop Time (30 min): $12
Labor Costs (40 hours): $290 ($7.25 Fed Minimum Wage)
Total Material Cost: $410
Cleaned Workspace images
Even though working on this project was hectic at times we always made sure to clean up after ourselves so that no mess was left that could negatively impact others.
Final thoughts and reflection
Building this mechanical carousel was a significantly more time consuming and challenging than we both thought it would be when we were initially brainstorming. At the same time though, it was somewhat rewarding to see everything come together and work, even if there were improvements we could have made. This project merged engineering, fabrication, and artistic design into a single, functional model. Watching the horses gallop up and down as the carousel spun was pretty cool in the end.
