In total, this project took me about two to three weeks to finish, including preparing the illustrator file, making the low fidelity prototype, editing the laser cutting file, creating a medium/high fidelity prototype and finally post processing the pieces to make the high fidelity model.

In general, the finished marble ejector works smoothly and nicely (see video below).

So first of all, I started out with understanding how the marble ejector can be assembled. By looking through the pictures in the book and some simple sketching, it is easy to gain a general idea of how the model works.

Then, I made the illustrator file for laser cutting. Following the same procedure I described in Homework Assignment #2, 2D sketches of pieces were made. It is worth noting that in adobe illustrator, there seems to be no straight-forward dimension adjustment tool, but by using rectangles and scaling up/down the dimensions of the picture by a factor, the same goal can be achieved in a much more time-efficient way then by only utilizing the rulers.

Shortly afterwards, I laser cut all pieces using cardboard and made a low/medium fidelity prototype with these pieces and straws (see picture below).

This prototype was very useful in providing some first understanding of the marble ejector. However, there are some certain problems associated with this cardboard prototype. First of all, the bar connecting the circle piece and the upper support was too thin and too short, and therefore caused pieces running into each other while turned. Also, the open space between upper and lower layer of cardboard allowed for more chances of jamming. Furthermore, as it’s easy to see from the picture, the two circles are not properly centered.

One lovely coincidence was the inner diameter of the holes match exactly with the outer diameter of the straw. This helped a lot when trying to assemble this prototype while later on blinded me from the fact that diameter of dowels would be a totally different scenario.

After a completely failed trail (mostly because of the diameter of holes and diameter of dowels could’t match), I modified the illustrator file and made a functional medium/high fidelity prototype using .125” wood (pieces of marble ejector) and .25” wood (pieces of outside box) and .25” acrylic board (see picture below). Pieces of same shape were stacked together to create feeling of layers and help with the motion.

At this point, the general shape of the marble ejector was already ver clear. When cutting out and assembling pieces, I intentionally selected the side without scorch marks to be the side above. All dowels were cut out using hand saw, so the ends were pretty rough. Nevertheless, the marble ejector was already able to work for about 20 smooth turns (usually afterwards the support ran into other pieces, but by pulling the handle back and forth, the ejector would be all good again).

In order to reduce the probability of jamming, I modified the two large pieces to the left and right of the center circle and started preparation for the final piece. The dowels were also cut using a pipe cutter (I think pipe cutter is suitable for dowels with small diameter but this use might not be the best choice) to look cleaner and smoother. Dowels were then fixed to the bottom board using super glue so that nothing would fall off. After making sure all pieces can fit together, I also post processed them by staining the five sides of the box and upmost surfaces of all pieces. Marbles with diameter of 35/64” were then filled in, and the box pieces was also glued together. The final prototype looked finished and relatively more professional (see picture below).