[Jay O'Donnell]

Originally Posted by Ether

Here's a very simple motor-sizing example.

Suppose you want to lift a 25 pound weight 4 feet in 5 seconds.

To figure the power required to do that, you multiply 25 times 4, and divide by 5. That's 20 foot pounds per second.

Multiply that answer by 1.356 to convert the answer to watts. That's 27 watts.

That's the absolute minimum mechanical power you will need. Increase that by, say, 50% to give you a safety margin. That's 41 watts.

Now look at the spec sheet for the various motors and pick a motor (or an identical pair of motors*) whose max output mechanical power is greater than 41 watts.

One you've selected the motor(s), you can compute the appropriate gear ratio.


* the power of an identical pair of motors is twice the power of one of those motors

Are there any simple examples like this for anything besides lifting weights? I've heard this example before (and it's a great example for helping understand how to pick motors for a lifting mechanism) but I was wondering if there were any simple ways of thinking about other mechanisms. Even just good rules of thumb from experience would be appreciated.