A Quick Intro:
I have loved making kinetic sculptures since high school. I was first introduced to the art form when I stumbled upon a YouTube video featuring the work of Arthur Ganson, whose application of mechanical principles resulted in some of the most stunning movements I think I have ever seen. I was also later inspired by Reuben Margolin, whose sculptures focus on sine waves and a replication of natural movement through mechanics. As a creative and as a budding engineer, I created a small scale duplicate of Arthur Ganson sculpture my junior year of high school, and made one or two small and semi-functional sculptures of my own design. With the tools of Georgia Tech at my disposal, I have been able to come up with more designs and ideas that would have thought possible back then. Sisyphus is my largest mechanical sculpture to date, and I’m excited to showcase the sculpture and my process! I have always loved the concept of Sisyphus as an artistic inspiration. The cyclic nature of his eternal punishment (to, for the rest of time, push a boulder up a hill only to have it roll down the other side) is not only existentially charming but also a great complement to pair with the cyclic nature of sine waves. Thus, my over-sized-marble-machine brain child was born!
First, of course, came a bit of planning. I always have to fight the urge to jump right into a sculpture, as my eagerness will often get the best of me. I started out with the concept of a camshaft-powered mechanical staircase, which is commonly used in marble machines.
I did a bit of math to figure out the relationship between step height and cam eccentricity (easy math, turns out it’s just one half). From there I determined what I wanted my starting step height to be and how long the staircase was going to be. I originally chose to start with a 2″ tall first step, but later found it to feel a bit too stubby considering I planned on using a 2.25″ diameter pool ball as the ball in this sculpture. So, I decided to make it 4″ tall and to make the staircase 12 steps total. With a plan in mind I also made a quick list of the necessary materials, which changed here and there as I progressed through the sculpture.
Like any engineer I value efficiency, so I wanted my camshaft to be strong enough to push heavy blocks of wood without requiring too much effort (or money) to make. I decided to stick sections of PVC pipe to a dowel in order to create a camshaft that was both uniform, low-friction, and easy to make. By using 2″ inner-diameter PVC pipe and a 1″ diameter dowel, I achieved exactly that and with an oscillation amplitude of almost exactly 1 inch. Gotta love those nice round numbers! My step height was then also determined by the camshaft’s eccentricity.
After an hour or two in the wood shop, it started to take form! Each piece of PVC was cut on the bandsaw with a fence set to ensure equal lengths. I also made the steps (described just ahead) alongside the camshaft, as the step length would determine the length of each cam. By lining up the steps I could determine the location for every other cam in one direction, since each neighboring cam would have to be offset 180 degrees. I threw together stands on either side out of scrap to help with the gluing process, which also ended up very useful because they supported the dowel such that gravity could ensure every cam was perfectly in line. I actually made the mistake of starting to glue it when it looked like this, not realizing that I would in fact have to put more cams in between them…
Luckily, I caught myself fairly quickly and was able to slide the neighboring cams sans glue while the first set dried. I did manage to get a cool picture before I came to my senses:
As for the steps you can see in the last sketch that I planned to cut in a slight slope for each step to ensure that the ball would roll cleanly from step to step. I actually achieved this my by making mirrored pieces, each with a slight slope forward and a slight slope inward to keep the ball centered on the step. I made these cuts using the miter saw, which is adjustable around 2 axes. They were made such that the trip from the back to the front of the step was just under a 0.25″ drop. That way I could choose a 0.75″ step height interval to accommodate the 1″ cam offset.
That very slight angle is clear in the picture on the left. I originally bought 2×3 planks for the steps, and used the planer to smooth them (as seen in the picture on the right) down to the clean dimensions that I noted in my sketch above. Each half was glued together to form the step for all twelve steps. After that, I had the camshaft and steps done!
The next step (pun intended) was to design the frame that would hold the stairs all neatly above the camshaft. As I was working on the cheap I went with MDF (medium-density fiberboard) over plywood, as I didn’t need a whole lot of strength for the piece that simply held the blocks in place. I ended up buying a large piece and using it to make the base as well. Unfortunately I got a bit too absorbed in the process and don’t have any pictures of just this frame, but I can share yet another sketch of my planning the size and the cuts (you can also see me tracking the creation of each step height as I cut the blanks for each step):
Since the side walls are identical, I was able to make one cut across a rectangle to get both using the table saw with a jig to set the angle.
As I started to see these pieces coming together, I noticed the potential for a problem to happen. I used epoxy to secure the PVC slices to the dowel, but overlooked the fact that the PVC is so smooth it gives little to nothing for the epoxy to grab onto. Predictably, as I brought the camshaft to and from the Invention Studio, the slightest bumps knocked a few slices of the PVC right off of the dowel. I realized they needed to withstand much more than they currently were able to, so I used tiny screws to help secure the PVC to the dowel. Using mechanical fastening, they became much stronger. To keep the PVC surface nice and even (minimizing the friction between the cam and the step) I filed the screw heads down flush.
To be even more sure that the weight of the steps did not become a problem, I used a nice big Forstner bit to remove some weight from the steps. This also had the added benefit of making the whole thing much easier to lug around!
While a bit repetitive, it’s incredibly satisfying to watch the wood flake off and pile up. The smell of the pine also became very strong during this process – yet another unexpected benefit!
Here’s what all the stairs looked like at the end. Between the reduced weight and the strengthened cams, this thing was ready to be assembled. I had determined the height at which I wanted this all to rest and then made supports that could hold the frame at this height and let the shaft thread through perfectly centered underneath it. After a little wood glue and clamping, I had my piece ready to be mounted to the base:
Mounting it was a bit of a process, as the base board was pretty big, and mounting something so tall meant I couldn’t easily turn the whole thing on its side and screw it into the right location on the base. So, I decided to just get under the table myself! After drilling the pilot holes into the bottom of the support pillars and the countersunk through the base, I spaced two of the tables a few inches apart to allow myself to get under and drill some nice big screws through the base and into the supports.
After a bit of an awkward squeeze under the table, it was mounted and ready! The screws I used were over 3″ long, so I am happy to say you could probably hit those supports with a bat and that frame wouldn’t budge.
The Return Track:
Once I reached this stage, all that was left was to mount a hand crank to the camshaft and put the track in to allow the ball to roll back onto the first step.
Unfortunately, this is also where I got a bit too into the groove and forgot to actually document the process itself. It was, however, pretty straightforward. I cut lengths of 3″ PVC pipe in half to create semi-circular channels that could be used as a track for the ball to roll in. Each channel was only sloped very slightly to keep the ball from gaining too much speed. I had 1 piece of track to retrieve the ball at the top of the stairs, 3 pieces to deliver it back towards the bottom of the staircase, then 1 more to place the ball right back on the first step.
Each piece was mounted on two pillars, with the further forward of the pair just slightly shorter. I actually decided on the kerf of the miter saw blade as the appropriate amount to remove to keep a very slight slope. Each piece of pipe was epoxied to the top of the pillars, but I made very sure to rough the PVC thoroughly with a file/rasp this time! This helped immensely with making the glued joint very strong. Each pillar was attached to the base similarly to the supports for the large frame. Here’s what all the steps looked like assembled:
The three lengths of pipe delivering the ball backwards each have their own tiny step to mirror the steps taken up the staircase. Each 90 degree turn is also a large step down, which also made it easy to not worry about any curves. The crank was simply another piece of dowel mounted 2.5″ off-center from the main shaft using a piece of plywood retrieved from the ever-useful scrap bin.
The last piece of PVC lines up perfectly with the last step in its lowest position:
After completing its trip, the ball had juuust enough energy to roll off the back of the first step, so I added a simple backing to keep it on the step.
Lo and behold, I had a fully functioning mechanical sculpture! Here is a picture of the final product after I had brought it home:
While not the prettiest thing to look at, I am personally a big fan of the “Home Depot aesthetic” I achieved, as it is representative of the true DIY nature of the project. The beauty of this sculpture comes from its motion and its nature, not its materials. And of course, here is this bad boy in action:
I am excited to say that this piece is being featured in the Georgia Tech Art Crawl alongside a lot of other great art made by Tech students. I’d also like to thank the Invention Studio for the tools and resources that made this sculpture possible, and thank my roommates Charlie and Lizzie for helping me carry/transport this clunky and awkwardly-shaped beast around campus. Thank you for reading!