Just went through a couple of days trying to get my cheap chinese made GT2560, which came with a Prusa i3 Clone (CTC D5983), to communicate with arduino. I was getting repeated stk500v2_ReceiveMessage(): timeout errors from avrdude through both the arduino IDE upload function, and running it off the command line. Turns out my GT2560 had an ancient bootloader and needed a different protocol, I usby blackwind14 - Sanguino(lolu)