My working clock MOC

First let me say that it is amazing how well dust shows up in a photo but not when you're holding the thing six inches from your face.

I made this a while back but I refuse to take it apart because I can't imagine topping it. I set out to make a working clock that kept decent time and even though it took a year, I did it. Here are the gear reductions necessary to take an electric motor outputting 360rpm and split it into one channel of 1rpm for the seconds hand, one of 1 revolution per hour for the minute hand, and one of 2 revolutions per day for the hour hand. I couldn't figure out how to output the seconds hand but the gear providing it is easily accessible so it is possible.

360rpm motor with 12 tooth gear -> worm gear

worm > 36tooth

36tooth > 8tooth via axle

8tooth>40tooth via gear

40tooth>24tooth via axle

24tooth>40tooth via gear <--seconds hand output

Here's where it diverges. The two small worm gears show the two outputs. The one on the left which is connected to the large black gear makes the minute hand. That's a 60tooth gear and the worm gear translates the 1rpm output from the 40tooth turning it into 1 gear tooth per minute, making the 60tooth gear a minute hand to which you can attach whatever you like. I went with simple brown hands for both minute and hour. The worm gear on the right begins the process of making the hour hand.

worm>24tooth

24tooth>worm

worm>36tooth

36tooth>12tooth via gear

At that point it's outputting 2 revolutions per day so there's the hour hand. The rest of the "plumbing" is just getting that output to where I could make an actual hour hand out of it without altering the 2rpd output.

There were probably 4 or 5 working designs which were altered to get it down to a 10x14 base. Accuracy varies with Lego battery packs but I believe with one of the third party motor systems it could be made to keep time reliably.

Finally, I made this final design able to easily break into two pieces. At that point it fits into an 8x8 base but the first gear in the chain (the 40tooth turning the two worms) needs to be turned at 1rpm to get accurate output. With a variable speed motor, that'd be easy.

I think that's everything. And yes it did take a year. Most of that was making large models without worm gears because I didn't know what those were yet. Once I learned about that, the design shrunk and it stopped exploding every time I turned it on LOL.