Quote Originally Posted by TopJimmyCooks View Post
I was having problems running ~8 hour prints via pronterface - printer would just stop moving at a random point several hours in and stay hot. Pronterface showed a random "k" in the terminal. Research showed this problem is related to the ramps board getting too hot and disrupting serial communication. I have solved this with a ramps fan...
This suggests to me that it may also be a good idea to mount the MEGA2560 board on spacers or standoffs, not flush to the wood frame like the build instructions say. The spacers or standoffs would allow at least some convection airflow behind the MEGA2560 board to help minimize any hot spots there. For something to affect USB communications, the temperature sensitivity has to actually be on the MEGA2560 board, and it gets essentially no airflow because of the boxed-in nature of the RAMPS board and the shield connectors in between the two boards.

Don't get me wrong - keeping the stepper drivers cool is still a smart thing to do. There just may be more than one thing going on. For stepper drivers to cause the MEGA2560 to mess up, heat would have to soak from the stepper driver board, to the RAMPS board, and then to the MEGA2560 board.