How do I make a chain rotating around 2 gears complete a single rotation in exactly 60 seconds?
I'd like to start off by declaring I am new to this website and have little understanding of technology as of yet. If my question has been answered before I apologize, but I haven't been able to find it in the forum.
I've recently started tinkering with 3D printing as a bit of a hobby and am trying to make items that are more than just odd looking. One of the things I'd like to create is the following clock found on youtube: http://www.youtube.com/watch?v=4S2DSteBLDY
Now this clock is made with Lego and its creator has labeled it as a 'proof of concept' as the 'lift' that delivers the ball, which should represent a minute, actually only counts ~55 seconds. For an actual clock I'd like it to have 60 seconds per minute and I am wondering if I can calulate the specs before I spend money on printed prototypes that dissapoint..
So using 2 Cogwheels/gears with a Chain that picks up a ball every 60 seconds (so a full chain rotation) based on an electric motor. I've found several 3-9v electric motors, but all seem to have rotations in the thousands whereas I'd expect to need like a few dozen rotations per minute(?). The clock I am trying to make is smaller than 20cm and I'd like for the chain to span a max 16cm in the final clock.
1) How do I decide the right Gear? size/teeth?
2) What Electric motor/power source would suit a very low amount of rotations?
3) How can I time the motor/gears to complete a cycle in exactly 1 minute?
Thanks in advance for taking a look ;)