Intro

When faced with the assignment of making two mechanical models, we researched a variety of wooden contraptions that could be fabricated with the tools we’ve learned how to use. We narrowed our options down to a mathematical modeled toy; a collapsable chair; a lock; a flywheel, and a pendulum. Each project presented unique challenges that we considered when picking our favorites: the flywheel and the lock. The flywheel and the lock emerged as the two best options for fabrication, because their designs are more reliable than the pendulum and toy, and they are more mechanical in nature than the chair. Additionally, we chose the flywheel because we wanted to make a machine that we could modify until it worked perfectly, and we chose the lock because it was an intricate precision machine that presented a unique challenge.

Both of these required and utilized precise drawing cutting methods for proper assembly, which we were able to accomplish using Adobe Illustrator and the Boss laser-cutting machine. The assembly process required a variety of hand-held power tools and modifications to reduce friction, ensure stability, and personalize the design. We enjoyed using both precision drawing and cutting machines, and customizing the parts with hand tools, dowels, string, and paint.

Low-fi Prototyping

For each of our projects, there was a main central challenge we faced when it came to constructing our piece. For each of these challenges, we took to low-fidelity prototyping to help solve our problems.

For the Flywheel and Governor, the challenge was designing the pins in which the axle spins upon.

For the F&G, we tested, with items off the low-fi rack, different pin designs. In particular, we cut the wire from pipe cleaners, cut off the sharp part of safety pins, and cut off parts of toothpicks. We tested these by embedding them in play dough and trying to spin a dowel on the tested item. We found out that the toothpick was the best at providing low-friction spinning while keeping the wooden dowel in place.

For the Wooden Lock, the challenge was designing the shim that lives in the locking mechanism.

We tested different shim designs using materials from the low-fi cart. We used pipe cleaners, foam pieces, and popsicle sticks to see which material worked best for its application. Clearly, the popsicle stick worked the best. The other two were less than ideal, but were good representations of the size and shape of the shim in the mechanism. Frankly, this low-fi step was not particularly necessary, but it did help us explore options that might have not been as obvious to begin with.

Sketching & Drawing

The bulk of the fabrication process took place in the drawing and cutting phase. We modeled the flywheel and the lock from books supplied in class. The lock had an especially time-consuming drawing process, because it was composed of three distinct layers of geometrically complicated shapes. The drawings were made out of combinations of curves that came together tangentially, with perfectly spaced notches and other shapes cut out at somewhat arbitrary locations.

Challenges, Modifications, and Failures

The biggest challenges we encountered when making the lock and the flywheel came up during the assembly process. With the flywheel, our original model had a lot of friction, causing the middle dowel to not spin easily. To fix this, we tried sanding down the ends of the dowel to eliminate the friction between it and the top and bottom of the device. This was unsuccessful, so we cut off about half a centimeter from one end, and had it spin with absolutely no contact with the top and bottom disks. Following this, we tackled the friction between the governor and the dowel by sanding them both down, which was successful. We had to drill miniscule holes in the governor (pictured) that were just large enough for a toothpick, which was hard to do in a piece of wood only 3/16” thick. Our largest modification to the flywheel was cutting down the weights and the end of the governor to the exact angle that they met the poles of the stand and their largest radius. This resulted in weights that were spherical at one end and flat at another, and a flywheel that spun to its full potential.

For the lock, we had to modify the design at multiple stages to account for incorrect drawing missing materials, and a weak shim. The lock had three distinct layers that had the same outline shape. At first, we drew the outside shape as a rectangle for one and a horseshoe for another. We went back and re-cut with the same outline for each once we realized this would pose assembly and finishing challenges. We also had forgotten to draw one of the curves in the interior of the middle piece, which posed a challenge when we tried to fit parts inside, so we re-cut that piece.  When we went to assemble, we had drawn for ⅜” dowels which the OEDK did not have, so we replaced the dowels with nuts and bolts and increased the thickness of the whole lock by 2 more sheets of wood to account for the length of the bolts. The last problem we had was that our shim did not have enough of a push-back against the lock arm, so we super glued a pen spring to the edge of the wood and directly across to the shim.

Details, Construction, and Finishing

After laser cutting the components, we were able to fit them together with relative ease after some light sanding. We used wood glue, super glue, and hot glue in various applications to keep our components together. In places with wood-to-wood contact, we opted for wood glue. In places where quick setting and adhesion was crucial, we used super glue. In places where a larger volume of glue and quick setting was required, we used hot glue.

Once finished with the structural side of our projects, we had free reign over how we wanted it to look. We chose to use spray paint for our F&G, and chose a color scheme of blue and metallic grey to represent Rice colors. We covered our wood with a clear coat.

On the top of the F&G, we decided to stencil in our initials, “C” and “H,” with thumb prints on either side for some artistic and individualistic flair.

For the wooden lock, we wanted to accentuate the natural beauty of wood. To achieve this, we used coats of shellac to finish our plywood and did some light sanding after it dried. We decided to use heavy-set brass bolts to keep the lock together for aesthetic reasons.

Overall, we were pretty happy with our finishing process. We thought that the processes we went through to add some flair to our projects were worth the time and effort, and ultimately resulted in a higher quality finished product.

Final Product

In the end, we are left with our final products: a fully functioning flywheel and governor that demonstrates the effects of increasing moment of inertia through the redistribution of mass, and a fully functioning wooden lock and key that demonstrates the versatility of laser cutting and rapid prototyping.