kestrou wrote:Why are they harder to keep in tune? Is it because of cheap tuners, or what?! Inquiring mind...
But I *love* the idea of doing a siggy JoBo Guitar in 3/4 size - what would be epic and really play to getting younger kids into the blues!!! 
Kevin
I guess it is more 'intonation' rather than 'in tune'. The very short scale means as you move up the neck, a lot of the fretted notes are not perfectly in tune with the desired note. Plus the shorts scale = very low tension on the strings, so the slightest pressure can overbend the string and put them out of tune if you are not careful. Even picking the string too hard can make things snap from a semi tone too high to too low.
The best option is to increase the string tension and placement of the harmonics on the neck by tuning them up a fifth or so, which tends to bring everything back into balance.
But it is a bit of a double edged sword. As mentioned, the initial setup is really easy for a young newbie to get their hands around and to be able to fret notes easily. However, you have to keep a close eye on things, as once they begin to master the basics, the intonation issues will cause problems as they struggle to maintain accuracy and "sound like the records" so to speak. Then it is probably time to move to a full size.
JBLP Gold Top #129 - redubbed "#1 in Oz"