3D printable cat feeder (2020) | Hacker News Reader

3D printable cat feeder (2020)

piotr.westfalewicz.com

85 pointsjsiepkes65 comments

Here is my (much lower tech) 3DP solution to feeding my cat. He is insane and will eat as much as he can. If he was free fed he would die. If he eats from a bowl his food is gone in 30 seconds and he gets agitated.

https://www.thingiverse.com/thing:4335532

This looks nice. My cat is the same and I use plastic bottle with a couple of holes.

I always had the impression that feeding your car (or any pet in general) was important social interaction for the animal. Automated feeding is at least cool for when you are not around much or for a few days only I guess.

Maybe the cat is 3D printed too...

Just joking, but actually, 3D printing works with living cells, though not yet up to the level of printing an entire animal :)

https://en.wikipedia.org/wiki/3D_bioprinting

Feeding the cat is an important social interaction as well as a sure-fire way to get the critter to show up when you want it to (assuming the cat is even allowed to go outside of course, this is not a given). In that respect a cat feeder is a net negative...

That said, this is a well-executed project which integrates a number of skills - theoretical, mechanical, logical - to produce something useful.

From what I understand for dogs it's very important for you to feed them, but for cats it's more important that food is made available to it regularly and consistently than from you specifically.

If a cat is hungry and knows you provide food, it will keep trying to figure out ways to make you give it the food which can lead to very strange and negative behaviours.

However if a cat learns that food will show up in a mysterious box at precise times, it will just wait until that time which will make it happier as it understands what it has to do to eat (wait) and you happier because it won't be scratching at you and yowling

Yup. I had a very "food motivated" cat and our lives was made much more pleasant by setting a "food alarm". That way she wouldn't bother me until the alarm goes off.

My current cats are free-fed but they get quite annoying if their bowl runs low. (they know how to get your attention)

My experience is that cats often start yowling at the machine about 20 minutes before they run. It's probably more of a case by case thing.

I don't think my outdoor cat give a flying flip whether I'm around when it's eating the mouse it caught.

Hand-feeding is important for kittens and feral cats, but once they are grown and domesticated it is less so. They do like you to be involved, but there's quite a bit of annoying behavior once the cat learns that you feed them the first thing in the morning. I guess if I wake you up early ...

I've pushed my cats' breakfast time back a few hours after I wake up so they can't directly associate "human is awake now" with "it's time for food!"

They've since stopped waking me up before my alarm goes off, and I can even sleep in a bit on weekends.

This was easier to do when my office was full remote for COVID, being in New England we're starting to reopen now.

I've got an automated feeder that drops food at 3AM because I got tired of getting up at 3AM to feed them - they would get pretty insistent. I hand feed them the rest of the day unless I'm going to be out and then I turn on the other feed times on the feeder.

I really like that this weighs the cat; having regular, non-intrusive cat health metrics is particularly useful. Weight change can be a sign of a variety of other issues, but also probably a bunch of non-issues, so _only_ weighing a cat on an annual visit to the vet is less useful but it's quite a pain to manually weigh the cat each day to see trends. Even if only to calibrate the amount of food to dose over time, it's a useful feature.

Nice project!

I own a Wyze scale and I noticed my cat standing on it. So, I created an account for her. She steps on it often enough that the wyze app gives me weight charts for her. I bet it would give me readings multiple times a day if I just set it in front of her food dish.

I just have a baby scale I plop my guys on occasionally. And then I record their weight in an iOS note.

Weighing your cat and paying attention to their digestion (recording vomiting frequency, inspecting stools) really goes a long way towards keeping a cat healthy.

What a gentle cat ... I know cats that would have immediately dismantled the things for research purposes.

Cats are scientists.

I like a good overengineering! :3 Very nice to watch / read.

Also: see his blog for posts about the PCB design and STLs etc: https://piotr.westfalewicz.com/blog/

In a similar vein, having fostered 30+ cats, I've found that using a "food tree puzzle" is especially useful. It's a good way to let them have snack and entertain themselves when they feel like it, without letting them potentially binge eat. (This is in addition to wet food as primary meals)

This is awesome!

With all that data you could do some ML model to make sure your cat is on proper weight (or study the patterns just for fun even, if you later don't apply it), like delivering more or less food or at appropriate intervals.

This is a bad idea. 3d printed objects unless filled with food-grade resins are not food safe as they cannot be cleaned (ridges of the layers) and tend to release a lot of not well characterized compounds.

> This is a bad idea.

Why did you have to add this? The rest of your post raises a valid point and then suggests a way to address it.

Is one small addressable flaw enough to render the rest of the project "a bad idea"?

I wouldn't call creating a health hazard for your cat a "small" flaw.

...unless you fix it, as described. Then it's not a flaw at all.

The rules here say to read each post with the most positive interpretation. Snark is never welcome, and that could have been said differently e.g. "A great idea! Be sure to use food-grade resin!"

Fair enough. Your alternative phrasing sounds much better!

Thanks for the reminder. I suppose I'm somewhat desensitized to snark these days; that's not a development I like.

Me too! I find myself deleting posts as often as I write them. In that case I go back and read some of what you have written, to remind me how to be calm and considerate.

Me? Calm and considerate? Do you even read my comments?!

Seriously though, thanks. While I strive to be what you just said, I also delete roughly half of my comments before even submitting them (and every now and then, few minutes after), and I'm not really happy about the rest. I'm pretty grumpy these days, I'm starting to hate the technology business more with every passing moment. Is this too much HN, or just youthful naivete expiring?

(Few years ago I learned that I won the third place in a ranking of HN's top posters of profanities - according to some dataset someone is keeping on Kaggle. This dubious honour made me tone down my language quite a bit.)

I've never won third place in any contest! Congratulations! I'm impressed.

Why, thank you!

In the spirit of keeping the positivity train rolling, you're the third person (after my wife and daughter) to make me smile today, so consider yourself the 3rd place winner of this impromptu contest!

I’m no feline toxicologist but cats only live like 12 years. I don’t think that is long enough for this kind of thing to really have any effect.

Plus given it is dry food, I wouldn’t loose too much sleep. I see animal food and water stored in all kinds of dirty, janky contraptions.

Dry food is full of oils and other chemicals that can do a real number on porcelain and metal food dishes that are designed to the highest levels of food safety standards, if those bowls aren’t cleaned or changed very frequently.

$DEITY only knows what those kinds of chemicals could do to an object that was 3D printed from materials that were not designed to the highest possible levels of food safety standards.

$DEITY only knows what kinds of toxic chemicals could be leached from the 3D printed materials, or could be created from the combination of the 3D printed materials and the oils and other chemicals in the dry food.

I realize that some people don’t care, and some other people don’t feel like they have a choice. And some people have cats that are finicky eaters and will refuse anything but their favorite dry foods.

But you wouldn’t feed your kids a lifetime diet of McDonalds McBurger and McFries with McShakes for every single meal of their life. Why would you do that to your cat(s)?

Yes, we feed some high quality dry food. Because our cats insist on a certain amount of that. But we also try to focus the feeding on high quality wet food instead. We are not perfect, but we are actively working on getting better.

Oh, and the average lifespan for an indoor/outdoor cat is about seven years. For indoor only cats, this is about fourteen years. But there’s also a long tail to where it is not too unusual to have cats living to twenty years of age, or more.

Obviously, there are some regional and breed-related variations to these nationwide averages. And if you live close to a green belt with lots of wild animals like foxes and coyotes, maybe the average lifespan of an indoor/outdoor cat is significantly reduced.

YMMV.

For a print this size, I wouldn't use resin. I imagine he used FDM. You might want to consider printing food-related items in PLA. The ridges do present a problem, but could be mitigated by sanding or coating (again, food-grade).

PLA isn't considered food grade but a marginally more expensive and difficult to work with, PETG, is food grade.

I don't think switching to PETG is an automatic win? You still have a rough, porous surface that can trap bacteria.

I stay away from food-related prints but I thought the best method was to print in whatever reasonable material you want and then coat it in something food grade, like resin. Then you get the material and print properties of PLA, PETG, whatever but food safe.

Or use the print to make a mold for casting food grade resin.

I believe they were suggesting using a food safe epoxy resin coating, not using a resin printer to make the part. Honestly, since it's dry food the usual food safety risks are fairly limited.

Came here to comment the same thing. Please don't put food on 3D printed surfaces, for humans or animals.

The clear food bin in the video looked like a “normal” bit of plastic—almost like a large licorice container. The only other part that is in long contact with the food is the actual bowl where kitty eats from. Design it so it fits a dishwasher safe bowl of some kind and you are good to go. The “guts” where the food falls through has minimal contact and for a dog or cat I wouldn’t loose too much sleep over. For humans I might do something more…

That being said… cleaning the “guts” might be a challenge and I can see it getting kinda skanky over time. Either reprint the parts periodically or find a way to clean them.

This is awesome. And the data can be really valuable. I think feeding and litter box habits are some of the best indicators for a cat's health.

I was about to do this with a watering station. After reading it took them 1.5 years tho, I’ll probably reconsider.

One thing I've learned over the years is it usually isn't worth trying to custom build something you can get on Amazon for $50. The adult in me knows this but damn is the kid in me dissapointed.

There are plenty of cat water fountains out there.

I would be very suspicious of any claim for the handling of cat watering solutions that cannot be handled with one of the existing products on the market.

But I would be happy to discuss that matter further, if you really think you’ve got a game changer.

What a shame. There are a dozen automatic dry kibble feeders you can buy for $50. The dashboard/stats are kinda all trivia. This is okay for short trips or fortunately young/healthy cats.

But what will really push the cat robot meta forward is a feeder capable of refrigerated wet food dispensing.

Yes! Wet cat food is so unpleasant to deal with, despite being arguably much healthier than kibble. IIRC, since cats prefer to get their fluids from food rather than drinking water from a bowl, wet food goes a long way in preventing dehydration and associated kidney issues.

I guess the reason we've never seen a wet food dispenser is that the only thing worse than cleaning gross wet food residue from a bowl is cleaning it from an overengineered electric dispenser.

I think a wet food dispenser would be fantastic, but you are right in that there are quite a lot of hurdles to it -- spoilage, the often unpleasant smell of wet cat food, the tendency for it to gum up the works as opposed to the more tractable to automation kibble, which merrily rolls along.

My gut feeling here says that any solution in this area is going to involve some kind of can engineering, maybe as far back in the chain as having specially designed wet food dispenser cans.

Refrigeration, too, would come into play unless you were working on a one-redesigned-can, one-serving paradigm. Perhaps a Peltier cooler with the waste heat going to warm some kind of cat friendly pad, as well as the food once served (given that they are carnivores, I am betting that cats would prefer wet food the approximate temperature of mouse guts).

And do not get me started on the struggles of multiple cats, where one or more cats is on a special diet.

I think wet food dispensing could honestly be very healthy for cats (or dogs) but we just haven't spent much time engineering for it.

They already have cat food pouches. Do you want a Juicero for wet cat food pouches?

TBH, I really don’t think Juicero solved any of the actual hard problems you would have for the automation of the serving of wet cat food.

I think it is a little stronger than preference, my understanding is that cats are supposed to get the majority of their water intake from their food AND that their tongue is not very efficient at drinking water, unlike a dogs which is very efficient.

This [1] video does not state my conclusion, but it does (in less than two minutes) show slow motion footage of dogs and cats drinking. You can see that the dog curls its tongue and visibly gets much more liquid up compared to the cat.

[1] https://www.youtube.com/watch?v=295bNJiTA20&ab_channel=Slate

Maybe they need a giant over engineered press that requires internet connectivity to scan and validate each bag of wet cat food. We could make it a subscription and each week customers would get fresh bags of healthy, organic pre-masticated cat food.

It will be like Netflix meets Nesspresso but for cat food!! We could call it juicero, er…“catero”!

But seriously. I’d love a good solution for automatic wet cat food.

What a shame?

Cat mate's rotating feeder works well for this. You dish out 5 portions, pop some ice packs underneath it and it will rotate at the given time to reveal the food. Not perfect but it lasts ok overnight, especially if you put in the next morning's food frozen.

I did start building an arduino powered copy of it using a peltier plate and some fly prevention mechanisms. The prototype worked well but since I'm at home 24/7 these days the project fell off my priority list. Maybe this will inspire me to finish it.

https://pawbot.com/ has been in various stages of product development for years now, the last I heard of which was an attempt to reduce scope & cost

I built a wet food pet feeder I called "Catzenpup". Give it a look. I'm not working on it now, but it did work great!

https://www.facebook.com/catzenpup/

Garrett

Will there be an automated cat litterbox integration soon ? ;)

Really awesome build!

Actually you can teach your cat to use standard toilet and add there some sort of automatic flush.

There are existing automated cat litter box solutions.

I don’t see any need to reinvent that wheel, but if you’ve got some specific ideas, I’d be happy to listen.

Yeah, I'm going to need something a lot more robust than that to keep my cats out of the feeder. They rip the lids off of the metal cans I use to store cat foot. :-)

Side note, what the blog software he's using? Looks really nice

If you view the page source: "Hugo 0.55.6 with theme Tranquilpeak 0.4.3-SNAPSHOT"

> Please note: the views I express are mine alone and they do not necessarily reflect the views of Amazon.com.

Why would they? Because of a little diagram of using AWS IoT, Lambda, and S3? Weird disclaimer.

Cool project though - I particularly like graphing the cat's weight too, seems like it doesn't really overeat just because it's available. I've never had cats, but I think dogs would basically just wolf it all down every time you filled it up. Though that could be an interesting experiment, assuming that was the starting point, teaching them that the food is plentiful, and they can just use the feeder when hungry.

> Why would they? Because of a little diagram of using AWS IoT, Lambda, and S3? Weird disclaimer.

I'm guessing he added that because he's Amazon employee.

Because he works for Amazon.

That might even be a standard footer across all of his blogs.

Oh ok. It doesn't really make sense without disclosing that though.

He does. That’s how I know he works at AWS.

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