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[on:]

hey all,

I'm trying to create a miniature version (less balls) of this just because it looks cool:



It looks like they attach string to a ball and then this gets moved up or down on the y axis. Together they create a 3d object.

I  thought about stepper motor to move the balls up and down accurately but they are expensive especially as i would need loads so thats out of the question!!

I then thought of modding some mini servos to have 360 rotation but can't work out if i will be able to still maintain accuracy needed to postion the ball correctly?

Then i thought about standard dc motors with a gearing system and B&W sensors so that as the motor turns it can detect repeating blocks of white and black to detect where it is but thats a little to complicated!

Anyway i was wondering if anyone had any ideas on the accuracy of modded servos? can i still position it accurately? Or does this sound like a stepper motor job?

[Reply #1 on:]

If you got enough mechanical leverage, you could probably do that with 180 degree servos. You just need to make sure that the movement from 0 to 180 gives you enough height, using a large arm or wheel or whatever is driving the string.

Also, there exists inexpensive small stepper motors. But I imagine the problem is the driving thereof? As long as the current draw is low, you can use very inexpensive transistors for an H-bridge, but you still have to control it somehow. Times a thousand or however many balls you want to control...

Hmm. Even at $10 per completed ball assembly, a thousand balls is $10,000...

[Reply #2 on:]

Hi, first sorry for my english but it isn't my mother language. Me too am working on the same project, iv'e found on ebay a cheap stepper motor with an uln2003 drive board, two stepper and two driver board cost around 6 euro, and it can easily move a little ball or something similar, if you wont more details contact me in a private message for the links. for now i'm tryng with four motor drived by an arduino mega board, that support up to 12 motor in theory, and i've done some things like a wave, working all the stepper at the same time, if you wont more information reply this or contact me, bye. Riccardo