“Countless shooting stars streak across the night sky… If you can pick the right one, it will carry your wish to thousands of distant worlds” – Adrian Spencer Smith, Honkai Star Rail

ad astra et ultra [designing – GATE 1]
“To the stars and beyond”

As we sit in a classroom merely 30 miles away from the Johnson Space Center, all we can do to marvel the world beyond us is admire the stars that signal our place in the universe. It was this thought that inspired our design. Perhaps space wasn’t far off. Perhaps we just needed to make space come to us. That is, we wanted to make a system resembling an orrery, except we wanted a rocket to rotate around a planetary body. In addition, we thought it would be cool if the rocket not only rotated in a different direction, but also had vertical motion. In trying to account for these criteria, we devised the following design.

Our initial design would work in the following manner: A handle would turn two gears on different levels. On the bottom level, the gear would turn two subsequent gears. The final gear would be connected to a shaft, thus turning the planetary body. Meanwhile, on the middle layer, the gear would only be connected to one gear (thus turning the planetary body and this gear in opposite directions). On the middle gear would be a box, in which a crank-shaft mechanism (Mechanism 421) would be housed. Of course, the crank-shaft still needed to be turned. As such, we thought we would use a stationary gear above the middle layer, such that the interaction between the rotating box and the stationary gear would force the crank-shaft mechanism to turn; we could then use that vertical motion to move a rocket vertically.

sapiens dominabitur astris [Cardboard – GATE 2]
“The wise one will rule through the stars”

For Gate 2, we started to test our design with cardboard. Since Gear Generator was still not working, we didn’t have high expectations for our gears, but we wanted to test everything else out.

As expected, due to the inability of Gear Generator, the bottom gears were nonfunctional. Despite appearing to mesh together in Image 3, they wouldn’t turn properly. Strangely enough, the middle gears worked perfectly fine, with the larger gear turning when the shaft turned. Moreover, we realized we needed some form of support system to align the layers, as can be seen from the diagonal shafts in Image 3. Finally, regarding the box, there were a few issues. For one, (although it was most likely a limitation of cardboard and masking tape) the final platform was being pushed at an undesirable angle, as seen in Image 4.

In addition, when interacting with the stationary gear, it appeared that the vertical gear had too much freedom. Instead of turning, the gear would simply move out of the way. Focusing on the stationary gear itself, we dimensioned it completely incorrectly; in our cardboard prototype, it intersected where we intended the handle’s shaft to be. Both of these errors can be seen in the following video.

 

With this knowledge, we devised a solution for each of the problems. Evidently, once Gear Generator worked, our first problem would be gone. As for a support system, Iñigo designed 1/2” squares that we would stick pieces of wood into, thus ensuring the alignment of our system. For the box, we thought that if we had multiple layers of shafts and cranks, we would apply an even force over the final platform, thus preventing it from rotating. In addition, we hoped that a change in material would solve the bevel~esque gear meshing issue; we assumed the cardboard did not provide enough of a counter force, thus allowing the dowel to move freely via destroying the cardboard. Should a material change not be enough, we also planned to include a spacer between the wall and the vertical gear to assist in providing a countering force. Finally, we aimed to redimension the stationary gear and its associated vertical gear.

Per ardua ad astra [WOOD – GATE 3]
“Through adversity to the stars”

Focusing on the crank shaft mechanism, Kyle came across a few issues. Luckily, our intended solution for the angling of the platform was a success-a similar angling never occurred. And yet, an angling in a different axis took its place. The platform now tilted in the following manner (see Image 5)

Although we’re still not entirely sure why this happened, Kyle has a theory. Perhaps the shaft connecting the straight member to the platform was too tight, thus causing the platform to angle on its way down. From there, gravity further acted on the platform, applying a moment that caused it to rotate around the shaft, overall causing the observed rotation. As a corollary, keeping the platform in the upright position meant competing with gravity. And why do that when it can help us instead? Kyle realized that, by turning the configuration upside down (such that it matched the depiction of Mechanism 421), gravity would assist in correcting the rotation. After all, the rotation would then pull the platform upwards, which would be countered by the downwards rotation that gravity provides.

Otherwise, we carried on. The dowels holding the rocket were made and sanded down such that they could slide through the top holes. Nonetheless, the dowels were too flimsy, refusing to move in a purely vertical manner. As a result, we made small squares with holes drilled in them, effectively restricting the motion of the dowels.

A video of the working mechanism can be seen below.

 

We continued onward, attaching another rocket to the other side of the box and using the laser cutters to cut out the gears designed with Gear Generator. Finally, we cut out circles of varying radii, hoping to put them on one shaft to form our planetary body.

That is, we cut out the parts needed for our project, but we had no clue as to if the mechanisms would work or not. We attempted to test the interaction between the vertical gear and the horizontal internal gear, but without good supports, the test had intrinsic jankiness to it. As shown in the video, we saw that the gears were able to mesh at certain points, so we assumed that placing fixed supports would also fix the interaction.

hinc itur ad astra [To the end]
“from here the way leads to the stars”

Although we initially chose to use an internal gear, after consulting other blog posts, we realized that others simply used an external gear for their bevel gear~esque mechanism. As such, we decided to follow suit, using Gear Generator once more to design another gear. To test Mechanism 421, however, we still needed a way for the middle gear to turn without an explicit shaft. Thus, we thought to use a ring to force the middle gear to follow a predetermined path (a circle). Nevertheless, we were unsure as to how much friction the interaction between the ring and the middle gear would generate, leading to the compromise seen.

Unfortunately, it appears the gear connected to the handle shaft exerted a horizontal force on the middle gear that the ring parts could not counter; the middle gear shifted every time, signaling the need to use a full ring. This realization can be seen in the video below.

Now that the ring was in place, the box was glued on, with the edge containing the gear being tangent to the hole of the middle gear. The stationary gear (the most recent gear formed via Gear Generator) was placed with the help of 1/2” dowels, a roll of duct tape, and random wood bits that we cut out.

In testing the interaction, it appeared that the middle gear would pop up randomly- perhaps a counterweight was needed. Given that the box contained a fair amount of wood, we looked for a material that was denser than mere wood, and we found it in the form of metal. See, it was already midnight when we reached this point, so the Wet Lab was quite locked. Thus, the only readily piece of metal around came from Kyle’s failed diamonds.

Triangles cut, they were glued onto the middle gear. Luckily, the aforementioned pop up seemed to have lessened with this added counterweight, though they did still happen. Examining the issue, it appears as though the problem could have arisen from one of two (or both) issues. Firstly, the middle gear was popping off the ring; adding an extra layer may prevent it from doing that. Secondly, the interaction between the vertical and the middle gear was imperfect; sanding the teeth of both gears may help them mesh better.

In trying the first method, the resulting friction was quite undesirable, leading to a quick sanding. And yet, after the sanding, we noticed that the pop up still happened, thus forcing us to consider the second, more labor-intensive method. Evidently, we just sanded down the teeth until the mechanism was able to go through one full rotation without a pop up. It is, however, to be noted that the number of teeth on both gears are relatively prime; we honestly had no clue if each distinct interaction would work. We just had to hope it would.

Sic ituR ad astra [FIN]
“thus one goes to the stars”

With the objectively most complex portion of the project done, we moved onto assembling and post-processing the model. Wary of the effect that friction may have, we used small spacers to separate the bottom gears from the bottom layer. While our idea worked in the sense that the gears were able to spin freely, we discovered that the spacer used for our middle gear was too small; it kept rotating around an undesired axis. To fix this, we simply used a spacer with a larger diameter (a piece we cut but didn’t use), as it would provide a normal force to counteract any unintended rotation.

Sticking on a vinyl sticker onto the rocket, we were feeling quite good about ourselves. We chose to stain certain parts of our model, including the base and supports (which are simply two 1/4” wood planks separated by a removable 3/16” dowel), leaving the other portions unstained for now.

When assembling the model, we were forced to sand down certain shafts, as they created far too much friction for comfort. A bit of duct tape Tetris later (and screwing around with the dimensions of the shafts themselves), and we made the model seen in the below image. We wanted the wood glue to dry before continuing, so we called it a day.

Returning the next day, we created a final ring, or we meant to anyway. It appeared that the two layers were already at an angle, preventing us from fitting a continuous ring around the supports. Instead, we laser cut the same ring, but bisected. Furthermore, to hide the metal pieces, we cut a slot into a second gear before gluing it on top of the middle gear. Before our final assembly, we gave the model a final staining, choosing to use a dark color to contrast the light wood on top. Once dried, we used the power of structural duct tape to align the final portions of our model, allowing wood glue to fuse our project in place. Sanding until the time limit, we drew a final arrow to indicate the direction the handle should be turned. After all, the planets in the sky only rotate counterclockwise (except Venus).

And for a video of it working, see below.

Cost

30 hours of work for 2 people at $7.25 an hour (Minimum Wage) – $435

1 sheet of wood at $26.68 a sheet (Lowes) – $26.68

A fifth of a can of wood stain at $23.98 a can (Lowes) – $11.99

1 sheet of cardboard at $1.99 a sheet (Michaels) – $1.99

1 1/2” dowel at $2.09 a dowel (Fleetfarm) – $2.09

1 3/16” at $9.99 for 50 dowels (Amazon) – $0.20

A hundredth of a vinyl roll at $9.99 a roll (Michaels) – $0.09

Twelve rolls of very structural duct tape at $5.98 a roll (HomeDepot) – $71.76

Total: $549.80