Printing from SD card seems unstable for Prusa i3  

Printing from SD card seems unstable for Prusa i3

Hello!

I have tested to print two gcode files from SD card via LCD display on the machine. The LCD display is placed in front of the y-axis and ziptied to the threaded rods as the build instructions says. The machine was setup to just print in the air without any plastic fed into the nozzle(I even removed the idler wheel and the large gear).

Now to the core of the problem: After a few layers printed, the x-axis suddenly moved to the x-endstop and even tried to go past it. Then it continued to print where it left off and after another few layers it moved again to the x-endstop - but this time it stopped a few mm from it and returned to where it left off again. This behaviour is repeated for both the x-axis and the y-axis during the print from the SD card at what it seemed ramdomly events. Another time the machine just stopped completely in the middle of a print and waited for something to happen. I had to disrupt the print and try it out more times. The command to home all axis has been tested several times without any problems. The machine does this perfectly.

So what on earth is making the machine doing this ? Well one thought of what can be the reason behind this is named vibrations - a lot of them will probably find its way from the stepper motors to the card holder for the SD card. And the adapter for the SD card may be in it self prone to vibrations making it even worse regarding bad contact between metal to metal stripes on the micro-SD card.

The solution to this problem could be one of two easily found solutions:
1. Move the LCD display to another place on the machine where the vibrations are at minimum and use rubber of some kind to minimize the problem.
2. Use the USB cable for control and use the computer to send the gcode to the machine.

I tested to use the USB cable and sent the gcode files twice to the machine without any problems. The print lasted for more than 2 hours each and the machine never interrupted the print at any point. So for now I am happy to have found a solution that seems to work - I will let you know more later this fall how it has evolved. Til then - happy printing!

/Henrik - A Newbie in the 3D printing world