Feline Sustenance Amplifier

A Steampunk Cat Feeder

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An automatic, network enabled, cat-theft-proof, dual-feeding, steampunk-themed cat feeder.

Many moons ago, I made a dual-cat feeder, using stepper motors and an Arduino. It had a lot of flaws. 

  • It was made out of a repurposed cat-litter container and was therefore very ugly. 
  • The cats discovered that if they picked it up with their claws and dropped it, they could shake food out of it. 
  • I knew very little about design, so it was very difficult to assemble and maintain.
  • I knew very little about power, so it would shut itself off after each feeding, probably because of a overpower situation.
  • I knew very little about components, so I used the suboptimal ones in many cases, like giant butt splices instead of solder sleeves. 
  • Most seriously, the stepper motors would melt and fail after a few days of operation, presumably due to poor quality controllers or incorrect implementation on my part. 

I scrapped the project before a big move, but have been wanting to apply the lessons learned from that project to a new and improved cat feeder. 

The requirements for this cat feeder are as follows: 

  • Aesthetically pleasing
  • Secure - not vulnerable to my cats robbing it anytime they want a snack
  • Configurable remotely via network (Wifi)
  • Solid construction
  • Ease of maintenance
  • Low food warning
  • Food capacity for two weeks or more
  • Painless food refilling process
  • High reliability

  • Crossbracing

    Joseph Marlin07/03/2022 at 22:13 0 comments

    One of the findings from the most recent project log, where I built a prototype of the hopper-to-feedwheel mechanism was that the system was extremely flimsy. It required a great deal of duct tape, was all out of tolerance, and all sorts of parts didn't join up right not due to improper dimensions but due to insufficient structural design. 

    I have now added extensive crossbracing to secure the mechanism. Part of that also included designing the cover that slides over the motor for aesthetic purposes, and I think it turned out well.

    Above is a rendering of the full device so far. As you can see, I still have not redesigned the chutes that lead from the hopper to the wheels, because I can't figure out how.

    But the cross bracing looks good.

    Also visible, particularly in the bottom image, are the alignment shims. These slide into their little housings and ensure the wheel stays aligned inside the wheel housing. I made the shim housing a separately printed piece with alignment holes that I will glue into place as an assembly step.

    This allows me to still print the wheel housing on its side without a bunch of supports.

    Next up will be dealing with the hopper-to-wheel-housing chutes.

  • Double Wheel Attempt 1

    Joseph Marlin06/24/2022 at 01:43 0 comments

    I have added the hopper!

    The goal is to print this out of translucent blue PLA and put LEDs inside of it to make it look like it is glowing. 

    I have also printed the bottom feed mechanisms with both wheels and tested it out. 

    And wow was it bad. 

    I am ashamed to even post these. 

    Here are a list of failures:

    • I was unable to fit the hopper exit chutes into the hopper in order to mate them. 
      • I had planned on sliding them in through the top, but they did not fit through the opening. They also could not clear coming up from the bottom. 
      • See image #3 above.
    • As a result, I had to cut off one of the two mounting tabs. This caused the exit chutes to bow outwards.
    • This caused the wheel housings to pull outwards, away from the wheels. 
      • See images #1 and #2 above.
    • This caused extensive duct taping to be required, and even this was insufficient to prevent momentary violent jams due to the misalignment. 

    Changes required:

    • Redesign exit chute to allow mating to hopper. 
    • Add lateral supports between the two hopper containers. 
    • Further develop design to provide mounting of hopper exit chutes to main support structure so they aren't floating. 
    • Add flanges around the outside and inside of the wheel housings to keep the wheels from leaving the housing. Note these must be removeable because the wheels install by sliding onto the motor shafts through the housing. 
    • Don't get impatient and skimp on supports when printing parts. 

    And to stay positive, what went well:

    • The threaded inserts - these guys worked delightfully. See my previous project log for my learnings about using these guys. 
    • Dimensions - I've never used a CAD assembly before, so it's very pleasant to make a multi-part 3D printed contraption and have everything just magically be the right dimensions on the first try. 

  • Two halves make a whole

    Joseph Marlin06/11/2022 at 21:55 0 comments

    A coworker pointed out that McMaster Carr has CAD downloadable for many fasteners and other items. Armed with this time, I grabbed a STEP file for an M4-0.7 6mm socket head screw in blazing speed. 

    Otherwise, not much to report. I have mirrored over all the components on the left side of the feeder to the right side, and will now be working on connecting both halves to a shared hopper. 

    After the hopper is designed, I'll be adding some pipes to provide primary structure, and a few gears that turn with the feed wheels for aesthetics. Then it will be time to move from mechanical to electrical. 


    1. Shared hopper
    2. Pipe primary structure
    3. Gear aesthetics
    4. Shift to electrical work

  • A Brief Aside: Threaded Inserts

    Joseph Marlin06/10/2022 at 01:50 0 comments

    I've never used threaded inserts before, so I thought it would be worthwhile to learn to use them correctly. 

    For reference, I bought these

    If you're unfamiliar with threaded inserts, they're small pieces of brass with grooves on the outside and threads on the inside. You can secure them into plastic so you have a strong place to screw a bolt into. (Compare this to screwing a bolt directly into plastic - the threads would immediately strip. 

    The question is, how big do you make the whole in your 3D print to accommodate one of these? Online guidance varies, so I determined some experimentation was necessary. The outer diameter of the threaded inserts per my datasheet was 5.3mm. As a result I decided to test with sizes from 3.5mm up to 5.25mm, almost the size of the outer diameter. Here's the test rig I made to test these sizes. I've made this available for printing here.

    The general installation method for these bad boys is to use a soldering iron to heat the threaded insert up, then push it down into the plastic. This worked admirably. The operation involves pushing them in half way with the soldering iron, and then pushing them the rest of the way with a large flat piece of metal to ensure they're flat.

    As you can see, I installed threaded inserts in only the five largest holes. By the time I had reached 4.25mm, there was so much extra plastic melting around the insert that it was pushing up the bottom and out the sides. 

    I also found that it was challenging to ensure the threaded inserts solidified such that they were vertical. I was using a screwdriver to hold them flat while they cooled. I believe that instead, a large piece of metal would ensure equal pressure was being applied to all sides of the insert, thereby ensuring they cooled perfectly flat. Here you can see that the second-from-left insert in particular cooled off-kilter. 

    Overall, I found that the experiment was a good success. I felt that 5.00 mm is an optimal size for the threaded inserts. Enough plastic must melt to ensure a good grip is formed on the insert when the plastic cools, but not so much plastic melts that it risks intrusion through the bottom or out the sides. 

    I'll be using 5.00mm holes for all my M4 threaded insert holes for the project. 

  • On Art and Aesthetics

    Joseph Marlin06/06/2022 at 02:16 0 comments

    I've now started doing some basic art design. This has forced me to do something I never, in the course of my entire existence, thought I'd be voluntarily doing: art history research. 

    I can't recommend this article enough. In it, the author analyzes the art styles of the two main factions in Arcane - the orderly, wealthy Piltover, and chaotic, destitute Zaun. 

    Piltover uses primarily artistic cues taken from the phase of art called "Art Deco", characterized by geometric shapes and patterns. On the other hand, the underworld of Zaun is stylistically inspired by "Art Nouveau".

    The Art Deco style, aka, Piltover, is more appealing to me, and also much more practical for 3D printing and my extremely limited art skills, so I'll be moving to design based on that. 

    Here are some screencaps from the show I've been using for inspiration. Note the geometric shapes and clean lines. 

    I've decided to theme this cat feeder with hexagons, because they're a very fun mathematical shape, are very versatile, and have lots of fun opportunities. 

    Here's what I have as a starting point. The copper color are inset pieces that I'll print separately and spray paint copper-colored (color subject to change). 

    Finally, it has occurred to me that Arcane is not exactly steampunk, due to the presence of magic. After some research, I've seen a few folks recommend calling this magepunk. There's also a subreddit dedicated to something called Aetherpunk, which I think is pretty similar to what I'm looking for. 

  • Double the Wheels, Double the Trouble

    Joseph Marlin06/03/2022 at 00:26 0 comments

    I am excited to finally have some sort of an assembly coming together! 

    I have modeled the motor using the datasheet and some calipers.

    I have also discovered the magic of GrabCAD for things like standard bolts and nuts. 

    I have now started the assembly model of the actual cat feeder. I have added mounting brackets and the wheels to the motor. Sadly, when I did this, I realized that my wheels are not symmetrical, and so they would need to turn opposite directions in order to work as scoops like intended.   

    I could just design a mirror image wheel, or I could redesign the wheel to work if rotating in either direction. I must think on which is the better route to take here. 

  • Deployment Mechanism 4 - The Thrill of Victory

    Joseph Marlin05/30/2022 at 18:45 0 comments

    With no jams, highly reliable feed deployment, and simple geometry, I'm proud to present after four iterations, the feed mechanism for the Feline Sustenance Amplifier!

    Notice the much higher baffle, resulting in far better access to the wheel from the feed chute. Also notice the entire chute has moved laterally much closer to the wheel. 

    After extensive tests, no jams occurred, and food moved consistently and smoothly through the deployment assembly.

    What's next? I don't know. I'm so excited to finally have this working I haven't thought much about it. 

    I think next steps will be: 

    1. Modeling the motor
    2. Creating a motor mounting scheme that allows access to both sides (unlike this one)
    3. Getting two feed wheels going at the same time. 

    Looking further ahead, other things that need doing:

    1. Determining how to design some nice steampunky big gears
    2. Determining what kind of pipes I want to use for aesthetics
    3. Designing artistic design which manage to capture the inspiring melding of steampunk and art-deco so effectively used in Arcane. 

  • Deployment Mechanism 3 - Third time, not the charm

    Joseph Marlin05/30/2022 at 01:32 0 comments

    The iterative process continues. Here's the latest attempt. 

    One nice addition: accurately sized screws, to ensure clearance is ok. Additionally, the model is scaled up to prevent jams. Here's the concept of operations: 

    Unfortunately, the baffle wall separating the chute from the wheel chamber extends too far down, and there is too much horizontal distance between the wheel and the chute. As a result, while the destructive jam problem remains fully fixed, the food get stuck in the chute and does not fall into the wheel chamber. 

    The wheel design and chamber work well as long as food reaches the wheel, so I'm going to leave the wheel and only rework the chute for the next iteration. 

  • Deployment Mechanism 2 - A Cat Feeder For Ants?

    Joseph Marlin05/26/2022 at 01:38 0 comments

    Another design has come and gone. I think this one has some potential though! Biggest issue with this one is that I just made it way too small! 

    I have been trying to minimize size of test components to reduce printer filament usage, but it really bit me this time. The conveyances were so small that food got jammed up even not going anywhere!

    Anyway, here's the design. 

    The concept of operation becomes much clearer when viewed cross-section. 

    The wheel turns counterclockwise. Food flows from the bottom of the hopper into the wheel. The wheel continues to rotate and is deposited underneath the wheel. Note that it is not necessary to actually have a slot all the way through the wheel - a water wheel design would work perfectly fine as well. 

    Here's the assembled mechanism. 

    As you can see, really quite a bit too small. I had to tap the hopper repeatedly to get food to flow like a liquid out of the hopper downshaft and into the "loading zone" for the wheel. But as long as I did so food deployed successfully with no destructive jams. 

    I am encouraged enough by the performance of this model that I am going to do a second revision of it. Planned tweaks:

    1. Increase size in all three dimensions
    2. Fix an issue where at one point in the wheel's rotation, food can slip out in an unintended manner. 
    3. Increase room in the wheel chamber to further buy down risk of destructive jams
    4. Add a slight angle to the bottom of the food downshaft to prevent a "deadzone" where food could get stuck for long periods of time. 

  • Deployment Mechanism 1 - Fail

    Joseph Marlin05/21/2022 at 21:02 0 comments

    Learning from my mistakes of last time, I decided to actually test the food deployment mechanism before designing the final product. Pictured above was my first attempt. The concept of operations is simple, as illustrated below. The "water wheel" is turned by a worm-gear DC motor connected via a flange coupler. Food drops from the hopper into the water wheel, which turns, dropping the food into the chute where it would be flowed to a food bowl for consumption. 

    My biggest problem to solve is to preventing kibbles from getting jammed in whatever mechanism I use and jamming up deployment. This model is specifically designed to prevent these jams with the curved lip at the bottom of the chute intended to block falling kibbles from getting stuck. 

    After designing and printing the wheel and hopper/chute parts, I designed the test fixture. 

    This uses the following parts: 

    Other materials included M4-7 bolts/nuts/washers, drywall screws, scrap wood, and L braces.

    Finally, I connected it to a power supply and set it going! 

    Sadly, the results were disappointing. Although the fixture delivered food consistently and reliably, jammed kibbles was a big problems. 

    Roughly every ten seconds during active feeding, a kibble would become trapped between the wheel and the hopper chute. This would cause current to spike to 500mA (nominal 100mA), and more importantly, caused the entire fixture to jolt violently after the kibble got crushed or the jam cleared. 

    After only a minute of operation, there was significant damage to the lip of the hopper, which was specifically designed to prevent jams. 

    Sadly, I'm going to put this design in the bucket of unsatisfactory results. 

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tomwilliams wrote 05/23/2022 at 22:50 point

When dealing with a large volume or variable sized food pieces, you will likely find yourself better off using an auger screw design. The torque required for the stepper motor as well as the likelihood for jamming make this and the other horizontal wheel designs result in binding and failure, as well as can leave voids where old food can hide out.

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Andrew Burger wrote 05/22/2022 at 03:48 point

Nice graphics. What software did you use to produce them?

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Joseph Marlin wrote 05/22/2022 at 21:07 point

It's Fusion 360, a CAD program by Autodesk. It's free with a non-commercial maker license.

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Bharbour wrote 05/22/2022 at 03:01 point

Your basic mechanism is very much like a commercial cat feeder that has been working for us for 20 years. The biggest difference that I see is that it looks like the blades on your design are rigid, while the ones on the commercial one are somewhat flexible. This allows the blades to deflect rather than jam on the kibbles. My biggest complaint about the feeder we have is that the size increments for feeding are too coarse. one setting results in not enough food and the next one up is too much food. This could be corrected by adjusting the depth of the pockets, but that would be a difficult thing to do on the commercial feeder.

Anyway, good luck and i think you are on the right track.

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Joseph Marlin wrote 05/22/2022 at 21:09 point

Thanks! Using flexible blades on the wheel would probably be perfect. Sounds like a perfect excuse to get a direct drive extruder for my ender 3 so I can print TPU...

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Bharbour wrote 05/22/2022 at 23:02 point

Glad to help, if you want a picture, let me know. That motor is probably bigger than you need which will mean bigger motor drivers needed and lower battery life. The commercial unit we have will run for several months on 4 D cells.

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