He'd actually be feeding the wire by hand. Cost is also an issue on this as well. Using steppers to synchronize the strings at both ends isn't really a necessity either, he just thought it might be a good way to do it and I kind of agree if we can keep the driver simple and cheap enough. He's looking at $400 to $500 total on something like this.
Here's an interesting video of something similar but it looks to me that the motors this guy is using are way overkill for something like this. I was hoping that we could get enough torque out of a nema 17 or a small 23 or something like that.
[ame=http://www.youtube.com/watch?v=EDtQW1mbDf4]Piano bass string machine - izrada bas[/ame]
-Andy B.
http://www.birkonium.com CNC for Luthiers and Industry http://banduramaker.blogspot.com