This is something goofy I made which is inspired by the concept of a millennium clock. I’ve made plenty of things which spin really fast, but I’ve never made something which spins VERY slow; I think this qualifies.
I use it as a lesson for Robowrangler students. I ask them to calculate some things as a way of proving they learned their gear theory.
I thought maybe someone here would think it is cool.
No, it takes a lot of effort to turn even the 4th 60t gear from the input. I’ve had this gearbox sitting on my desk for a few months and every so often someone gives it a spin. Even after all this time we’ve been unable to advance the small wheel a noticeable amount (you can see the sharpie line we added when I first built the gearbox on the top of that wheel.)
If my 24 hours of lemons team took this with us driving from Detroit to San Francicso, strapped on the back of the back of the race-car for the full length of the race, and then drug it back to Detroit, the little wheel would have only turned about 40 degrees.
Another way of looking at this is 1 JVN small wheel degree is equal to about 168 miles. In order words, our trip to Atlanta this spring is only 4.5 JVN small wheel degrees. That doesn’t sound so bad.
:yikes:
How’s that Fluids studying going? ready for the final?
Neat gearbox…in the old days cars used to have mechanical odometers. The cable driving it turns 1000 revolutions per mile. The odometer has 6 digits, the first one turns one revolution per mile. I guess it’s a similar concept.
Reminds me of something the artist Tim Hawkinson made once. A ridiculous gear reduction, where the input spun at several thousand RPM, and the output would take hundreds of years to make one revolution.
I think this is awesome. I think I am going to borrow the idea for my team, but we are going to make a “Shipdate countdown clock” So Whatever day they build it they will have to calculate the right ratio for a ~60 day output cycle.
Now the real question, has anyone ever run a vex controller for 60+ straight days using a power supply?
Someone please correct me if I am wrong but wouldn’t you be fighting a force of 1/12(mass)(3*radius^2 + height^2) * 244140625 Newtons to get it started? Now, maybe if you put a crazy long lever arm on the small wheel’s shaft you could over come that.
Of course, even that number is almost nothing compared to the real number because you would have to account for starting the gears rotating too. This could be an interesting problem for more advanced students, What is the max length of a lever arm you could attach a 100 kg weight to and still not have the large wheel move? Have them run it both ways.
What I want to know is what the backlash is at the input gear. It has to be several thousand full revolutions of the input shaft. Which amuses me to no end, given I’m usually working with gearheads that measure backlash in minutes of arc…
We had a guy call us this past summer, wanting to use a Toughbox and a low power motor to slowly move a parabolic solar panel so that it follows the sun.
So… we found a small gearmotor package from Dayton, and used that as an input to the Toughbox. We bench tested this assembly and found out that the output shaft of the Toughbox was doing 1 revolution in about 18 minutes. Of course, this is much faster than the Earth is spinning, but it was a good way to use a very low power motor to move a 12 foot long solar panel.
