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Bob Kojima's Lego Rolling Ball Clock

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bobko69 / Bob Kojima posted this

of his Lego "Rolling Ball Clock" -- "This clock is based on the Arrow Handicraft Deluxe Rolling Ball Clock that was popular in the 80's.

"To tell the time read the hour from the 3rd row of balls. For the minutes add the 1st and 2nd row of balls together.

On the first row 1 ball = 1 minute. On the second row 1 ball = 5 minutes.

"My friend Chris Scheuerman asked me if i had ever seen a rolling ball clock before. He told me that he just got one and that i should come take a look at it and try to make one out of LEGO. I never did go over and look at his clock. In fact my clock was built strictly from pictures found on the web. I have never seen one of these clocks in person. I spent about 2 months making this moc and 1 month fine tuning and debugging.

"The ball holding, balancing, tilting, and logic was simple to make. It did take a few bricklink orders to get enough ribbed tubbing and soccer balls. The lift mechanism is what stumped me. I thought about it for about a month before i came up with a design that i thought would work. It still took a lot of tweaking to get it to work correctly. The real clock has a rotating arm that lifts the balls up to the top. I was originally going to copy the same rotating arm, but i would have needed a very long arm because of the height of the ball logic. So i went with the chain lift mechanism. It turned out very well.

"During debugging improvements were made like adding extra guard rails so all the balls would return to the ball holder and not the ground. One problem that i have not solved yet is the lift mechanism is not 100% accurate. Very rarely, 2 balls are lifted at the same time or no balls are lifted at all. But i think that the no lifts and the 2 ball lifts even then selves out because after running for 3 days at Brickfest PDX it was only about 1 or 2 minutes off.

"34 Photos and [MLCAD] instructions can be found here: ."


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