String breaks

[agibney]

Whenever I use an alternative tuning where the G string is tuned down, eg down to F, and then returned back to G, the string sometimes breaks. The break occurs at the machine head and not at the bridge. The strings I use are Martin Guage 13. They string usually has about 3 to 4 turns around the machine head. Is there anyway of preventing this or reducing the chance of this happening. Thanks.
Anthony Gibney

[agibney]

Thanks for the reply. It's a strange one as the string only breaks when I tune it back up, when the machine head is actually turning.

[Lentin]

I used to have the same problem but the guitar was an Ibanez Jumbo type bought in 1978.
The string (always the 3rd) got broken when it was 'cold'. So, what I used to do was to play for some time to get the string 'hot' and then to change the tuning to D or to the standard.
The string gauge could be Light or Medium, but the effect was the same.
With my Avalon I haven't had this problem yet (and strings need to be changed long time ago).