The trick is to be smarter than the animal with a brain the size of a walnut
“This will be great,” I thought to myself. “I’ll get one of those high-tech automated cat feeders!”
Wait, I should back up a bit. You see, the four-legged tenant of Dunki Freehold, who goes by Sprocket H.G. Shopcat, eats twice a day. She gets delicious healthy wet food in the morning, and less-good-for-her but nice-for-lazy-human dry food in the evening. The latter has the advantage of being easily dispensed by a robot. An automated feeder would save me one chore per day, and I wouldn’t have to worry about getting home late in the evenings. It’s also very handy for travel.
After some research, I decided on this model- the PetSafe programmable automated feeder. It has a large capacity, and really extensive programming options. For cats with food-security issues (common in rescue situations) this machine can be programmed to feed in multiple stages throughout the day. Sprocket seems to be much less stressed having her dinner spread out over the course of the evening. The reviews were positive, and people also said that the cat can’t get into it to steal food.
Those people have never met Sprocket H.G. Shopcat.
If there’s one thing I learned in this odyssey, it’s that automatic cat feeders are the equivalent of giving a piece of dental floss to someone serving life in prison. With infinite time, you can escape anything, and (it turns out) break into almost any robot.
The machine has a silicone conveyor belt driven by a continuous servo. A microcontroller times the servo’s operation to control portion size. The conveyor is gravity-fed by a hopper above it. The food falls off the end of the conveyor and down a vertical chute into an attached bowl.
Sprocket’s first gambit was very simple- she would nudge the machine with her little eight pound body, and some food would fall out. There were always some loose pieces near the end of the conveyor, and jostling the machine would send a few out. The machine is under a table, so I answered this first challenge with some stiff wire to anchor it to the table leg.
Undeterred, Sprocket then learned she could climb on to the stringers of the table to get high ground above the machine, then grab the top edge with her little mouth. She could then lift it and drop it, causing pieces to fall out. To deter this, I grabbed a heavy piece of steel off the junk pile and placed it on the machine to make it hard to lift with tiny feline choppers.
This made picking up the machine inconvenient enough that she switched tactics. Her next move was to lie on her back in the bowl, and stick her paw up the chute. She could paw the conveyor belt itself, getting it to move. This was very effective, netting an extra meal or more.
Now things are getting tricky. I needed to prevent chute access by paws, while still allowing food out. The position is awkward for her, so I fabricated a straight bar across the chute opening that would divide the space in half and make it so she couldn’t get a good angle to reach the conveyor any more.
This worked briefly, but she then returned to the lift-and-drop strategy. It turns out she’s quite strong, and managed to lift and drop the machine even with the chunk of steel on it. To combat this, I made a metal hold-down bracket out of some scrap metal and screwed it to the table. It was now physically impossible to lift the machine.
Undeterred, she returned to attacking the chute. Her old approach didn’t work anymore, but she quickly learned she could move to the side of the bowl and get a more vertical approach angle, thus bypassing the divider bar.
For the next round, I grabbed an old plastic soda bottle, and made an extension to the chute. This completely blocked access while still allowing food to slide down into the bowl.
This worked for almost two full days, which was a record. However, she chewed doggedly at that plastic soda bottle until she had destroyed it. In celebration, she ate some large number of extra meals while I was at work, and proceeded to throw up all over the kitchen. It was the best and worst day for Sprocket.
The idea of the chute extension was sound, it was just my implementation that was flawed. The junk pile coughed up a piece of 24ga copper sheet which I used to upgrade the extension.
Mostly foiled by this copper, she then went back again to the lift-and-drop strategy. This time she figured out she could rotate my hold-down clamp out of the way, and again the machine was free to lift. I responded to this by putting more bends in the clamp such that it was now wrapped fully over the lip of the machine, and could not be swung out of the way.
This worked for a few more days, but I was worried. She was managing to loosen the new clamp a bit over time, and I didn’t feel good that my chute extension would hold forever. She was working very hard to defeat all these new measures. What next?
Well, here at Blondihacks Labs, we know that there is no problem that can’t be solved with a lot of steel plate. Yes, it was time to go Full Furiosa on this cat feeding robot. I pulled a bunch of 1/8″ steel plate off the junk pile and got to work.
The goal was to completely enclose the machine, thus eliminating all possible access points. I also wanted a system that would completely restrain the bowl, and restrict access to the front part of it (to protect the chute area). The reason for using 1/8″ steel is that the resulting box will be so heavy as to be utterly out of the question for an 8lb mammal to effect change upon it in 3D space.
Despite my Furiosic zeal to armor the hell out of this thing, I do also need it to be functional. That means it needs a lid that I can open. The junk pile provided some nifty friction hinges that I think were left over from one of the failed Teddy Top iterations. They’ve been waiting in The Pile for their moment to shine!
I wasn’t taking any chances with the bowl, because it’s potentially a huge weak link in the system. If she gets that loose, all is lost. She’ll be able to get any angle she wants on the chute, and it’ll be cat vomit as far as the eye can see.
I made an integral band around the front of the bowl using the MAPP gas torch bending technique I’ve talked about before on this blog.
In that photo, you can also see the copper chute control. The idea here is to have an adjustable section on the front that I can modify as needed. I need the system to be such that she can reach all parts of the bowl with her paw, but not be able to reach upwards towards the chute in any way. The front edge of this copper shield is rolled upwards to make a soft lip, since her head and paws will be all up in there. The copper is easily removable in case I need to make modifications, or if she somehow destroys it and it needs replacing or repair. I tried to keep all areas that might contact the food copper or stainless.
I spent a lot of time sanding, filing, and polishing every corner and edge on this thing. I wanted to be sure there was no chance of her cutting herself if she rubbed, chewed, or pawed at any part of this box. This thing is so comfortable and safe to touch that you could roll it around on balloons and nothing would pop.
You might also notice in that last photo that it has a stylish old-timey patina. I hit it with JAX metal blackener instead of paint because I was afraid if she chewed on it, she would scrape paint off and get it in her little system. This seemed safer. Honestly, being steel, she has shown no interest in even touching it, never mind chewing or rubbing on it. Still, better safe than sad kitty.
The whole thing came out very unintentionally steampunk-looking, because of the patina, the copper, and the regularly-spaced bolts. All it’s missing is a few gratuitous gears. Maybe it should be called Professor Quinn’s Fantastic Patented Cat Confabulator.
The final security measure is to place the machine on a rubber sheet. This protects my cheap laminate from the steel, but also makes the machine immovable. Even something heavy can be slid around if the surface is low-friction, so I made it as high-friction as possible. The rubber sheet is actually a dog bowl mat. Don’t tell Sprocket- the indignity of that might be too much to tolerate. She might retaliate by chewing through the gas line on the dryer or something.
Moment of truth time. Does it work?
As you can see below, the copper shield is doing its job. She can still paw the food forward from the back of the bowl, which is actually a nice activity for her. Making dinner a project for cats is a good thing- keeps them occupied, and keeps them from eating too fast.
Interestingly, Sprocket has shown zero interest in probing this new feeder for weaknesses. It’s almost as though there’s a psychological effect of the imposing structure that is keeping her from even trying.
A friend noticed that the machine ended up with quite an art deco feel to it, so she made a logo for the front. I think it finishes things off nicely.
You might say I’ve won this battle. However I just spent 20 hours armor-plating a cat feeder. I think we know who’s really in control here, don’t we?