VEX Alarm Clock Challenge

I saw this over on the ROBOTC forums, which has very little activity, and thought it was an interesting challenge for the programmers while you all wait for the builders to get this years robot ready.

As an extension it would be fun to drive a motor with suitable gearing to move the hands of a traditional clock. Perhaps someone can create the first VEX cockoo clock

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I’ve been thinking about building a vex analogue clock that functions correctly, but I am too busy working on my competition robot

Hmm interesting… I’ve also been busy working on this years robot, but I’ve gotten to the point where I can’t really test my robot any farther then it has gotten because I don’t have enough supplies at home. If I find the time, I’ll try it out! Thanks for sharing it!

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So far there’s been no takers, so if anyone is interested it’s fair game at this point :slight_smile:

I plan on entering soon.

I’m not interested in the challenge but I love the idea of a vex clock!

So far I found out that the hour hand needs to rotate 2 times a day, the minute hand needs to rotate 24 times a day. If the free speed of a 393 motor is 100 rpm’s, then thats 6000 rotations an hour, and 144000 per day.

Who wants to start working out the gear ratios :stuck_out_tongue:

Or you could just hook up an encoder to it and write a quick PID loop :stuck_out_tongue:

This morning I was able to quickly put something together before soccer tryouts. I’ll post it soon. Would you prefer these forums or the RobotC forums?

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I’ll be watching both, it would be a tiny bit easier if they were all in the same place so ROBOTC forums would be preferred. Either way works though, I’ll keep an eye out here and there both.

When it comes to time you will have some issues because the motors don’t spin that fast over load.
I would recommend basing your number off of 50 rpm or something similar and then lower the power to get that speed.
Actually 60 rpm and then the second hand can be at a 1:60 gear ratio and so on.

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At 100rpm for the hour hand it’s 72,000:1 (torque). To get to the ballpark of that, you need an 8-stage compound gear reduction:
7:1 x 7:1 x 7:1 x 7:1 x 7:1 x 3:1 x 1.4:1 = 70,589.4. From there, you need some tiny, minute adjustments. Tabor is right, it would probably be a lot easier to aid your efforts by setting the motor to a lower value.

Imagine using that on a drive! Using 4" wheels, your robot would move ~12.56 inches in 1 day.

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