For the midterm project, I had to build a functional wood machine. We could choose a machine from two books and I chose the “Cam and Fork Machine” from “Building Wooden Machines” by Alan & Gill Bridgewater (which is project #3 in the book).

A description of how the machine works can be found in:

http://engi210.blogs.rice.edu/2016/02/07/cam-and-fork-wood-machine/

The machine would be built by assembling many 2-D pieces of wood that would be cut in the laser cutter. From a previous homework, I already had the detailed drawings of all the pieces, which helped a lot.

The first part of the midterm was building a low-fidelity prototype of the machine. I used cardboard for that. I also built it by assembling 2-D pieces, in order to see how difficult it would be to assembly the high-fidelity version. After doing it, I had a good idea of how to make the final version.

The first step towards the final version of the machine was doing some changes on the drawings to prepare them for laser cutting. Professor Wettergreen asked me to add a second fork to my machine to make it more interesting and in order to do that I had to make more changes on the drawings, but they were straightforward.

The second step was to laser cut the pieces. However, I had to decide first the thickness of the wood and how many layers of wood I would need for each piece. Because of the hole on the fork that should be trespassed by a dowel, the thickness of the wood should be the same as the dowel diameter. Measuring the available dowels, I realized that I would need a piece of wood with thickness 0.25 inch, at least for the forks. Luckily, I found a sheet of wood with this exact measure and did all my work on it. It was quite hard to fit everything on only one sheet, but I figured it out.

The third step was gluing the laser cut pieces together, because almost all the parts were composed of more than one layer. For that task, I used the well-known Gorilla Glue. It worked pretty well. I also cut the dowels I would need.

Fourth step was assembling. For this part, I used tape in some parts to eliminate some looseness. Also, to glue small parts, I used Super Glue because it is stronger than Gorilla Glue. Here, I also added some small extra components, like the handle and the balls on the dowel’s extremes to avoid its unwanted horizontal movement. I also had to drill those balls, which was a little bit complicated in the beginning, but after some trials, I got some practice. While assembling it I made some mistakes and had to unmount it twice (that was when I realized how strong was the Super Glue). After this step, the machine was working pretty well!(video here)

The fifth and final step was finishing the wood. I decided to stain it with oil so that it would look nicer. It was quite easy. I just asked other students and the professor about how to use the oil, then I got a brush and did it. Now, the cam and fork machine has its final form.

(Thanks Isabelle Cochran for the participation on the final video :P)