Inchworm Caterpillar Automaton by Dawlight

Dawlight

Art>Sculptures

GIF

Contest Winner

Animal Frenzy

Print Profile(5)

All

P1S

P1P

X1 Carbon

X1E

A1 mini

Updated (v3) - 0.2mm layer, 6 walls, 10% infill

Designer

4.5 h

3 plates

4.9(124)

V3 - [A1 Mini] 0.2mm layer, 6 walls, 10% gyroid infill

5.4 h

4 plates

4.7(22)

Updated v3, 0.2mm layer, 6 walls, 10% gyroid infill

4.4 h

2 plates

5.0(3)

Inchworm only - 0.2mm layer, 6 walls, 10% infill, A1 mini

14 min

1 plate

4.2(5)

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Description

Updates

2024-05-21:
Version 2 of the drive gears, handle and caterpillar as well as an updated print profile has been uploaded.
- The drive gears now leave less play in the system, reducing the chance of jamming, even without lubrication.
- The handle should be less prone to break, but might need some more force to assemble.
- The caterpillar is still delicate depending on your material, but hopefully less so.
- All parts are compatible with the old versions of the other parts.
2424-05-22:
Version 3 of the drive gears has been uploaded. They should be even more reliable than version 2. These are also compatible with all other parts regardless of version.
2424-06-10:
Version 3 of the crank handle has been uploaded. It's available as an handle_v3.stl under files for now, but I'll update the print profile when I get home.

The Model

I've always been fascinated by the movements of insects and other small animals, especially worms, larvae and caterpillars. I thought to combine this fascination with my more recent fascination for the conversion of constant mechanical movement into intermittent mechanical movement.

This is a simple, abstract automaton of a caterpillar crawling in circles on a leaf. It's based on, but not quite accurate to what is commonly known as an inchworm, the larval stage of the Geometer Moth.

Anyway! You simply turn the crank and watch as the caterpillar crawls its way around the leaf!

Here's a video of it in action: https://www.youtube.com/watch?v=e3_RjoHW6k0

Printing

I used mostly standard settings for all parts except the caterpillar itself, as the tolerances are quite forgiving for the mechanical parts. The covers could benefit from some ironing, though I haven't tried it myself at the time of writing.

No supports are needed if all items are orientated in the intended way. The raw model files have the crank and its handle oriented in a bad-for-printing way.

The caterpillar is a delicate part, and requires Arachne wall generation for best chance of a successful print, as well as making it more durable.

Assembly

There are no extra materials or tools needed for assembly, but for smooth operation, depending on the properties of your filaments, some kind of lubrication is highly recommended. Also, the outer lid, while being designed for press fitting, is intentionally not a very tight fit so as to facilitate easier disassembly. For a permanent solution, you could always glue it in place later.

Press the bottom and top driving gears (small, partially toothed gears) together, being mindful of the small pip keeping them correctly oriented to each other. They should hold together simply by friction.
Put the driving gear assembly on the driving axle pin, making sure the toothed side of the bottom gear is pointed downward as seen in the picture. Lubrication on the axle pin, teeth and smooth section of the gears is highly recommended.
Put the big gear with the curved slot on top of the other big gear. Make sure that the bottom gear pin is positioned in the slot as far away from the top gear pin as possible. Hold the two gears together. The teeth of both gears should align.
Drop the big gears into the base, making sure that a non-toothed section (any one will do) of the big gear assembly mates with the non-toothed section of the driving gear pair. Also mind the small protrusions on the inside of the base where the lid will sit.
Place the outer lid inside the base. The crank hole on the tapered side of the lid really benefits from some lubrication.
Press the crank into the hole by the driving gears and and click the crank handle into place at the end of the crank arm. The crank should stay in the hole with friction. Now is a good time to make sure that the mechanism works and feels smooth before the next step.
Press the center lid into place, minding the small pip that dictates the orientation. Observing the leaf pattern can help as well.
Fit the caterpillar on the moving pins. I found this to be easier in the minimally extended position. The worm may require some bending to make it conform to a nice shape, but I found that after initial tinkering it holds its shape very well.

Good luck, and let me know if you run into any issues!

Comment & Rating (206)

@PhilA

Boosted

Print Profile

Updated (v3) - 0.2mm layer, 6 walls, 10% infill

Really cool mechanism! Ended up breaking the handle so re-printed in PETG. Sometimes the gears would clash, lubricant helped. Very fun when it really gets going.

(Edited)

The designer has replied

@Dawlight

Happy that you like it! I'm going to make a small update to the handle since mine broke too. I'll also improve the tolerances for the non-toothed parts of the gears, which should help the mechanism run smoother with less jamming, even without lubricant. The springy caterpillar creates some resistance in the mechanism that I didn't account for since the original idea was to have it consist of separate joints (which didn't work out at all...). Hopefully, only the small gears and the handle will be all that needs to be reprinted.

(Edited)

@Dawlight

The updates have been uploaded. If jamming is your issue, I'd suggest replacing only the drive gears :)

@PhilA

Boosted

Replying to @Dawlight :

Thank you!!

@user_3665220650

Turned out great! The only (minor) issue is that the caterpillar gets caught into the handle every turn due to the bending at the center. 2nd issue is the spinning handle isn't all that easy to place into the spindle, which I can agree with. 3rd issue is the spinning handle is a BIT too small to grasp onto, would love to see a design where you can print both pieces together, and have a more rotating profile at the TOP of the spindle. Otherwise 9.9/10

(Edited)

The designer has replied

@Dawlight

Oh! The handle is designed to run over the caterpillar just as it reaches its lowest point. Very interested to see what your problem looks like :)

@user_3665220650

Replying to @Dawlight :

It's the opposite - it reaches the highest point :D

@lucyferror

Print Profile

Updated (v3) - 0.2mm layer, 6 walls, 10% infill

It works kind of smooth but gets a bit jammed after full turn when you need to use a bit more force to move worm and then it moves smoothly until full circle when it gets stuck at same place. My son struggles to move it at this point.

(Edited)

The designer has replied

@Dawlight

Have you tried the latest drive gears (v3)? I'd like to get to the bottom of the issues you're having if possible. The springy worm puts some friction in the mechanism that can be hard to overcome without some lubrication. But it all depends on the materials used.

@user_2015727639

The rotation is not smooth, and the small gears often become misaligned.

Show original

@Mikechrjensen

Boosted

Print Profile

Updated (v3) - 0.2mm layer, 6 walls, 10% infill

this is the coolest thing I have printet I love the size and the mechanic I have printet 2 to my children and they love it but the handle need something it keeps falling off