What is a good place for...

electric 12 volt motors? A project we are working on in school is a can crusher. Our can crusher has to operate at 3 cans per minute. We are planning on dropping a 15 lb weight (we can only drop it a MAX of 3.5 feet or so) and then retracting the weight via an electric motor. First, we don't know how much of a motor it will take to raise that heavy of a weight (we have 10-15 seconds to raise the weight).

What we need is a good, CHEAP, source of electric motors. We have a MAX of $50 to spend on EVERYTHING, so a great price would be $10 or so.

Second, our handout says it takes 1000kN to crush a standard can. Our 15lb weight is 66 newtons. I can't remember basic physics right now. So, another question is will that 66 newton object accelerate enough in around a meter to crush a can?

We shouldn't need a full 1000 newtons as we are planning on denting the can when it enters our can crusher, so lets figure 500 newtons needed to crush it. Would we be able to get 500 newtons of force after a meter?

Thanks in advance,
Spud

Car starter motor from a junk yard?

Hey, good call! I hadn't even thought of that. That would probably be PERFECT! Although, I would probably want to under drive it as those are normally only short periods, so I could probably drive it at like 10 volts or something. We'll see. That sounds like it would be great, and probably really cheap.

Thanks!!!

Spud

Stupid question:
Is it allowed to use a "piston" beeing moved by a electromotor wich is turning a threaded rod moving the "piston"? It's a great way of applying huge forces. I've seen cars beeing lifted by a simple cordless powerdrill...
Only possible probem could be speed, but since you have 10/15 secs between crushing, it should not be a real problem. Only thing to consider is the "speed" of the threads and the rev/torque capabilities of the motor.

I hope this made sence, my technical English is pretty much non existant.

Track down an electric wheel chair motor...12V, small enough to design around, and reliable.

--dan