How do you make an escapement with a balance spring?

I have a problem My cat has a weak stomache so he needs to have a lot of small meals during the day, but there's not always somebody at home, so I wanted to make a cat feeder device for this. I want to make a disc that rotates slowly, during the day, leaving open another segment of a cilinder after every period of time. In every segment of the cilinder is cat food(which is poured into it that morning) Under the cilinder I want a clock mechanism, with a balance spring. I want to make it with a balance spring because it shouldn't be too high, my cat needs to be able to reach it's food normally. I've made a mechanism with a pendulum before, but it was one meter in height, while now i want the mechanism about one inch in height. I thought only a balance spring would fit right in the cilinder under the feeder, but I never worked with one, I don't have one either. How does a clock escapement with a balance spring work? And how can I get a balance spring? Can I just roll a long metal strip intro a spring? My cat feeder doesn't need a complicated gear train, because whether it makes one revolution in 10 hours, or in 14 hours, that doesn't matter. thanks

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lemonie8 years ago
The balance spring escapement mechanism is for keeping accurate time. As you say, you don't need this to be that accurate, so it's not necessary. L
merijnvw (author)  lemonie8 years ago
It's also for dosing the rotation from the energy source. I want it to rotate real slowly. There doesn't exist any springs usable as an energy source, which naturally move so slowly that 12 hours after you release them, they are in their natural position. So that movement needs to be frequently braked, to lengthen the time the spring uses to get back into it's normal shape. This has to be done with a kind of pendulum and an escapement, a normal escapement won't fit, so I want to use a balance spring one.
Building clocks isn't easy and you need a lot of gears. I'd use an existing clock-movement, or a different mechanism. And remember that if kitty sees a partially-uncovered tray he may start sticking his paw in there and interfere with the movement (you know what cats can be like...) L
merijnvw (author)  lemonie8 years ago
okay, thanks!
Broom8 years ago
Ah, now I see why you asked for a "weak 12-hr motor". Since the cat might get smart enough to figure out he can overpower the motor, perhaps a wind-up alarm clock motor would be more appropriate. The metal gearing would prevent the cat from pushing the lid around. Before anyone thinks of it - clock hands are designed to slip if they encounter force. The gearing doesn't.
Goodhart8 years ago
Would it be easier to control this electronically? Timers are easy to build, and if not skilled in that area, one can get a lamp / appliance timer that has multiple settings for on/off.