Around 500 MB of 3D models in ~50 STL files, plus Fusion 360 archive made available under Open Source license.

The ultimate, cloud cat feeder

If you haven’t seen it before, this post is about the ultimate cloud cat feeder. See the product demo here.

STLs?

Before you start printing it, take a look at the cross section view to get a feeling what are you getting yourself into:

Cross section view through the center of the cat feeder Cross section view through the center of the cat feeder

Yes indeed, it’s heavily over-engineered cat feeder! Yes, there are existing, fully tested, working, automatic cat feeders (although I’m not sure there are cat feeders which weight both the food and the cat, and have the dashboard…). Yes, it’s not a fully production-ready product… and again, it’s over-engineered:

Explode view of the cat feeder Explode view of the cat feeder

STLs?!

Having that in mind, here are the files:

What needs improvement?

Despite the Lessons Learned published in the design post, I discovered a couple of new annoying bits in the current (v180) version. Don’t get me wrong, the cat feeder is pretty good even now, however to reach five-star, superb quality, I would change:

  • Access to the SD card: I’ve put it on the bottom, assuming it will be rarely accessed and the cat feeder look will be clean. It is indeed rarely accessed, but when you need to get it out, it’s a real pain.
  • Access to the internal parts: my assumption was I will be rarely reprogramming/tweaking/fixing the internal parts. The last assumption (fixing) was correct, but not the first two. In the new version I would make some kind of JTAG port easily accessible. I would redesign the cases so that the whole cat feeder shell could be easily split into two parts, exposing all internal components.
  • Improved food dispersion mechanism: currently the food screw crushes some of the dry food pieces which are getting between the food screw and the tunnel. I would experiment with elastic food screw (printed in flexible filaments - TPE/TPU) to avoid crushing the dry food, although it’s not that bad for my senior cat. I would also experiment with other, simpler dispersion mechanisms as: Meowton food dispenser by psy0rz although it might turn out to be less precise.
  • Bigger, replaceable bowl with easier cleaning: instead of plastic, 3D printed bowl, why not to use cat’s favorite ceramic/metal bowl? The idea was to make it easily washable, however if you could replace it (and put to a dishwasher), it would be even better.
  • More reliable weight sensors: HX711 with load cells Aliexpress link is simple and well documented way of measuring weight on Arduino. However, to get it really right it requires a lot of calibration effort, taring, scaling etc. Probably it requires temperature compensation as well. I’m sure there must be out there better weight modules. Something like a weight scale by I2C/SPI/OneWire. Do you know it? Please let me know!

What worked well?

  • The LED ring. It was supposed to be an indicator for me if the cat feeder is working correctly, but it turns out my cat figured it out and she loves it. She understands the meaning of moving light - amazing!
  • Another surprise for me is the lid closing mechanism. I thought it will be unreliable and a bit fragile. It’s not. Probably thanks to the Hall sensors, it’s one of the most reliable parts of the feeder. Moreover, because the lid fits the case precisely (leaving around 0.5mm gap), the cat doesn’t try to open it.
  • Dead simple, but awesome idea is transparent food container. Cat doesn’t care about it, but you immediately see if you need to put more dry food there.
  • ESP32 was a perfect choice. It provides encrypted communication with Amazon AWS cloud (cat’s personal data needs to be encrypted like your bank account connection, right?), it handles many protothreads quite easily and there is a LOT of space for the firmware.

Other resources

You can find more details on the cat feeder (building progress, features, technical details) here - all posts with cat-feeder tag.

Where are the software and the firmware code?

Please be patient - there are a lot of files and there are hard-coded certificates in the source code - I need to find and get rid of them. Check this blog/Twitter/FB page for updates - they will be coming in August/September.


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