(Our first inspiration is to make a string instrument that can actually create sound, but we abandoned this idea because it is too precise for us and it is hard to test the pitch)
Our formal project is an owl, since owl is rice’s mascot and also my favorite animal. I design the mechanical structure primarily based on the way how a lego of Hedwig that I have assembled works.
In our project, I undertook most of the mechanical parts, and Serena undertook most of the designing parts.
1.Sketch the AI files of the support
Originally we chose to use the thin stick with diameter of 14.4 pts. The setting of laser cut vector for the whole project is 15 speed, 75 power, 10 frequency.
Estimating the kerf, I set the diameter of the holes 16 pts and the rectangular assembling site 13.7*26 pts. My first plan was to have 4 places of bevel gears at gate 1. This is my design of how the owl can flap its wings:
Then considering this fundamental structure, I sketched the support of the column to hold the sticks and gears.
2.Print to test bevel gear
This was our first challenge during the project. Although I knew we should use cardboard at gate 2, it is impossible for soft bevel gear to work so I start my prototype with wood. The basic things for bevel gears to work is that we should leave some spaces of at the edge of the gear not to contact with the other.
However, the first gear I tried was not free to rotate because I drew the gear by myself. After I tried Gear Generator, the case became better. I tried several types of pressure angel and found out that 20 is the best for bevel gear to rotate. It was extremely important for me to adjust the length and width of the wood piece that holds the gear. Although the gear can rotate, the friction in between was so big that sometimes our components will be worn.
This is the video shows how our first bevel gears worked:
3.Design the rotation of the wings
The rotation of the wings should not be only one direction; it will make the movement too rigid. So we used 158 as our rotative method. Two axises are fix and other two are free to rotate that move the wings. For each axis, I put two donuts on each end to restrict the horizontal movement of those components.
This is the AI file:
This is the video shows how it works:
4.Connect central axis and wings
Because we need to ensure that the wings are flapping in one direction, we should also use bevel gears here so that one wing rotates clockwise and the other rotates counterclockwise. My first plan was to print gears with 4 teeth to make the rotation smoother but later I found out that in this case the teeth cannot be fully contacted to trigger the other. So I changed into 9 teeth gear. Here I met another great issue that the weight of the components will pull the rotating structure down so that the friction caused by contact will prohibit our rotation.
Each gear should be glued to the sticks to ensure the torque will be transferred by the axis. It was hard for me to determine the size of each gear because if the gear that directly triggers the wing is too big, the central gear will cost more torque to trigger it; if it is too small, it will be impossible to trigger the heavy wing.
This is my final proportion of the supports and the gears.
5.Magnify to scale and apply bearings
The thin sticks were too weak and easily curved, so I decided to change a thicker stick. It not only increases the strength of our prototype but also gives us the opportunity to glued bearings to reduce the friction.
The greatest problem appeared when we installed everything that we printed. The central gear was worn out, which indicates the friction and our structure strength was still terrible for our project. I bought machine oil and dropped it between the surface where wood and wood contact. Besides, we water-jet the central gear because aluminum is surely stronger than wood. The first night when we tried water jet machine, there was problem of too low water pressure, so it actually slowed our process until it was fixed.
6.Base and base-gears
This image shows everything about our base:
This is how everything worked before we assembled the decorative owl parts onto the mechanical support:
However, we noticed a problem that our base was too light as we rotate the stick, the base will move along. In this case, people must hold the base to let the wings flapping properly. It was too late for us to improve because the laser cut machine was fully appointed.
7.Postprocessing
Now it was the time to combine my parts and Serena’s part together.
Our nameplate was designed as an owl holding our names. Serena printed all the vinyl stickers, and we sprayed blue onto it together. It costed a long time for just putting and tearing off the stickers because the owl was small and precise.
Because all of our decorative components were engraved by the laser cutter, it was hard for us to choose a proper stain or paint. After several trials, we found the walnut color was the best, but it was nearly depleted. Then we bought one by our own.
After staining, we added wax on the surface of the owl to make it glossy.
Again we water-jet a handle.I quickly post processed this handle.
Finally we installed everything together and used super glue to enhance the structure strength.
Final video:
COST ESTIMATION
Labor:
Houston average wage $30/h
45h/person: 45*2*$30=$2700
Machine:
20 hour laser cutter:$20*20(https://www.accteklaser.com/understanding-the-operating-costs-of-laser-cutting-machines/)
1 hour water jet:$20(https://clients.wardjet.com/tools/waterjet-cost-calculator)
1 hour vinyl cutter:$10(https://www.sunbeltrentals.com/equipment-rental/floor-care/manual-vinyl-plank-cutter/0680500/)
Material:
on Amazon：
12 packs of plywood $70
5 packs of cardboard $23
5 packs of aluminum sheets $35
10 plywood：$70*10/12=$58.33
3 cardboard: $23*3/5=$13.8
half aluminum sheet: $3.5
1 oil:$6
1 stain:$18
1 wax:$18
4 180grit sandpaper:$1.33
1 wood glue:$4.38
8 super glue:$18*8/6=$24
8 wood sticks:$5*8/25=$1.6
Total:$3278.94
