For my final project, I wanted to incorporate something from my time at the radio station, so I decided to make a music box. I would be using a combination of #24 and #25 from 507movements.com:
24. Spur-gears
25. Bevel-gears
There was going to be one small issue for this assignment this semester: we will be mostly using cardboard instead of regular plywood due to issues with the laser cutter.
Original 2D sketch of music box. It’s suppose to resemble a vinyl player.
When determining dimensions of parts, I first thought of the size of the mock 7″ LP vinyl (we’ll refer to this as “LP disk” from hereon out). From here, I decided that the box to hold the gears should be 4x8x8″ so that the top looks proportionate to the LP disk. I then generated a box using makeabox.io. I also generated gears with approximate sizing using the following website: http://www.jeromeleary.com/gears/. In Adobe Illustrator, I estimated the scaling so that the gears would fit within side of the box. I then sent the file to the laser cutter.
.ai file used to laser-cut the box and gears
It took 2 tries to get the scaling right for the gears — the first time around, the larger gear was too large to be mounted on the side of the box, so I reduced the scale to 80%. This seemed to do the trick.
Assembly was probably the trickiest part of the project for me. What was difficult was aligning the gears within the box. Originally I had planned for 2 gears only, but because the size of the bottom of the box, I was going to need 3 gears: 2 for the bottom, 1 for the side. Aligning the two gears at a right angle was relatively easy compared to aligning all 3 gears so that the system would rotate together. If I were to go back and redo the process, I would create gears with bigger teeth.
For axles and the handle, I sawed short bits of 5mm diameter dowels.
Another issue was that the axle for the 3rd gear in the middle that would be connected to the LP disk kept popping out of its hole when the system of gears were rotating, so I had to glue down the dowel rod axle. This meant that I had to move the LP disk inside the box sitting on top of the 3rd gear instead of on top of the box (like I had originally planned) if I wanted it to rotate with the 3rd gear.
After several hours of tinkering with different gear configurations/placements of axles, I started some post-processing before finalizing assembly. I stained the cardboard with a nice dark oak color (I found out that I had to wipe the stain off immediately after application so it wouldn’t get too sticky, in comparison to staining wood, where I would wait for a minute or two before wiping). I then used acrylic paint from home to paint the bottom of the box and the disk black, with a little bit of red accent on the disk. I then used the vinyl cutter to make eighth-note stickers to decorate the box and fulfill the vinyl sticker requirement.
While I wanted the disk to spin as someone turns the handle, I also found during troubleshooting that I could also have the gears move if I were to directly spin the disk, which would have the other gears turning and rotate the handle. While it wasn’t how I planned for the model to move primarily, it does mimic disc scratching and DJing, which in the end was my ultimate goal of commemorating DJing at KTRU Radio for the last few years, so I’m happy with the happy coincident.
Farewell to ENGI 210 and Rice University.
Sincerely, a happy senior
Video of Music Box parts moving
Cost Analysis
- Materials: Cardboard (free) + Auxiliary materials (rags, vinyl sticker, sandpaper, stain, dowels, etc. — $5) = $5
- Labor: 12 hours @ $15/hour = $180
- Machinery access: Tools (CO2 laser cutter, hand tools, vinyl cutter) = $50 (TX/RX maker space membership)
Total: $235
