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# Nautilus Sculptures

Kinetic sculptures based on Nautilus gears

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Nautilus gears meshed together in different patterns and actuated by a motor to generate some interesting kinetic sculptures.

A logarithmic spiral is a curve whose distance from the origin grows exponentially with angle. The curve can be found in nature like the Nautilus shell. I recently came across a gear whose profile matches the above description and is called a Nautilus gear. The way two such gears mesh with each other is really mesmerizing. I printed one for myself to play with but was too lazy to keep turning it. So, I automated the motion and now use it as a desk toy.

The pattern can very simply be generated by some closed form equations and expressions that appeared longer than this project blog. For the mathematically inclined, here is a link to the page. I spent a couple of months solving the equations and came up with the coordinates that define the gear profile. Just kidding... I followed the path of least resistance and simply picked up the CAD file from Thingiverse and altered it to suit my requirements. Shout-out to Misha T for the upload.

The next goal was to figure out a mechanism to turn the gears. Motor of course... but then there were 2 issues:

• How do I hold the nautilus gears in place while turning?
• How do I drive the gears with a motor at a sane pace?

The answer to the first question was rather simple. Design a frame to hold the gears. The answer to the second question is also quite straight forward in retrospect but it was not immediately clear to me when I started. I knew gears can be used to reduce the speed and increase the torque but did not have much idea beyond that. I wish I had paid attention in my engineering classes. Oh well...  I can always attend classes at the Youtube university and that's exactly what I did. I prefer to watch simpler videos that are a good match for my intellectual capabilities and the videos are short compared to those 45 min to 1 hour sleep inducing lectures in college :)

I eventually ended up designing more than one contraption.

• Nautilus Twins (desktop version)
• Nautilus Windmill (handheld version)
• Nautilus Mania (wall art version)

The list of parts to be 3D printed and hardware components are all listed in the assembly instructions. For instant gratification, refer to the video but for anyone interested in the gory details, here is a huge wall of text for you. You have been warned!!!

# Nautilus Twins

I started with figuring out the gear ratio that I need. A reduction by a factor of 10 appeared reasonable given the motor I had. Doing the reduction a single stage would require a monster sized spur gear. So, I decided to do it in 2 stages each with factor of 3 reduction in each stage. I then modeled the two stages in Fusion 360 which is another skill I have picked up from the Youtube school of engineering. 608 skateboard bearings were used to reduce friction in gears and eliminate the wobble.

I did not feel any need for making any aspect programmable. So, did not have to worry about the microcontroller or coding. One could use an H-bridge to change the direction of rotation or change the turning speed or accessorize it with some lights, etc. and all that wirelessly.

# Nautilus Windmill

I then experimented with 4 of these Nautilus gears together and came up with a slightly more interesting movement. I decided to mount it on an epicyclic gear train (planetary gear set) as it rendered a more industrial looking background. I paired it up with the handle of the Thor hammer that I had made earlier as part of another project.

The initial version had the bottom most gear swaying sideways rather unpredictably. So, I introduced a guide to have it gracefully ride up and down vertically. This made a huge difference in its stability.

# Nautilus Mania

After building the handheld version, I got a bit greedy and decided to experiment with more number of gears. The above actuation and mounting scheme did not appear very scalable. So, I got back to the drawing board for a way to make things modular and therefore easy to scale. Here is what I came up with:

• A...

• 1
Nautilus Twins

## List of parts to be 3D printed and the required hardware components

• A 90 teeth spur gear. This would mate directly with the Nautilus gear.
• A compound gear with 30 teeth to mate with the 90 teeth gear to get the factor of 3 reduction in speed.
• A second gear in the compound gear with 45 teeth to mate with a smaller gear with 15 teeth to provide another factor of 3 reduction in speed.
• A DC motor which is powered by 4 AA batteries connected to the 15 teeth gear.
• A bracket to mount the DC motor.
• A housing that contains all the above components. It is split into 2 halves - front and rear.

All parts were printed in PLA with 0.28 mm layer height and a 0.4 mm nozzle on an Ender 3. The STL files can be found on Thingiverse.

## Assembly Instructions

• Insert the two 608 bearings in the slots on the front half of the housing.
• Mount a Nautilus gear on the shaft and insert the shaft through the 608 bearing from the front.
• Mount the 90 teeth gear on the other end of this shaft.
• Install the second Nautilus gear and shaft in the same way as above.
• Mount the compound gear on the second shaft and ensure that the 30 teeth gear meshes correctly with the 90 teeth gear.
• Attach the bracket to the rear half of the housing and then the DC motor to the bracket.
• Mount the 15 teeth gear on the DC motor.
• Complete the electrical connection as shown in the wiring diagram.
• Snap together the front and rear halves of the housing while ensuring that the 15 teeth gear meshes correctly with the 45 teeth gear in the compound gear.
• 2
Nautilus Windmill

## List of parts to be 3D printed and the required hardware components

• A Handle to house the motor and batteries for actuation. This component has been reused form one my previous projects, Enchanted Thor Hammer. Refer to the list of 3D printed parts from the Thingiverse.
• A Mounting frame to gear down the motor RPM and increase the torque. It implements a simple planetary gear train with a 135 teeth ring gear, 3 x 60 teeth planetary gears, a 15 teeth sun gear, a planet carrier, and a few 608 bearings.
• The Nautilus Gear display. It consists of 4 Nautilus gears mounted on 4 links using a few 608 bearings.

All parts were printed in PLA with 0.28 mm layer height and a 0.4 mm nozzle on an Ender 3. The STL files can be found on Thingiverse.

## Assembly Instructions

Assemble the handle

• Refer to its assembly instructions in my other project.

Assemble the mounting frame

• Equally space out the planetary gears inside the ring gear.
• Insert the sun gear in the center.
• Attach the planet carrier to the centers of the planetary gears.
• Dial in the gear train by turning the gears manually or using a power drill. Ensure that there is no binding. A little lubrication always helps.

Assemble the display

• Connect the links using 608 bearings.
• Mount the Nautilus gear on the links.

Attach the display to the mounting frame and connect the resulting assembly to the handle. Refer to the video for complete assembly walkthrough.

Front View

Front View (Closeup)

Rear View

Rear View (Closeup)

• 3
Nautilus Pair

## List of parts to be 3D printed and the required hardware components

• 2 Gear frame
• 2 Nautilus gears
• Pegs to attach the gears to the frame
• 608 Bearings
• Actuator

## Assembly Instructions

• Mount the gears on the frame. Ensure that the teeth are meshed as shown below.
• Mount the gear assembly to the actuator using the adapter.

Refer to the video for complete assembly walkthrough.

Front View

Rear View

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## Discussions

sylvia wrote 03/18/2021 at 14:21 point

I've been thinking (for people like me who as yet don't own a 3d printer) Would anyone sell me all the parts so I can just assemble them?

Please let me know if that works, and I'll be purchasing a number of them...

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tominohio wrote 03/18/2021 at 13:26 point

Could someone recommend an actuator?  I'm building the bloom model.  Thanks.

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Chief Points wrote 03/18/2021 at 04:20 point

Nice project, I think my wall needs one ;)

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Phillip Scruggs wrote 03/17/2021 at 18:38 point

Thanks for such detailed build instructions!

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tominohio wrote 03/17/2021 at 16:38 point

Hello, I am having hard time finding the parts for Nautilus Bloom on Thingiverse, especially the frame.  May you provide a link?  Thanks.

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Chief Points wrote 03/18/2021 at 04:20 point

I just clicked on the link for his Enchanted Thor Hammer Thingiverse post he mentioned for the handle parts and found the nautilus project under his Thingiverse account - https://www.thingiverse.com/thing:4788434

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tominohio wrote 03/18/2021 at 12:31 point

Thank you!

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Ken Yap wrote 03/09/2021 at 05:36 point

Very nice! 👍 Could watch these for ages.

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