My printer is printing a messy ball. CTC prusa from Ebay I bought this cheap prusa i3 variation from eBay. I setup everything and now I'm trying to print some gcode file from the SD card. Using PLA.

Here is a video of the mess! How can so fix this situation?:

https://youtu.be/Vz46tCcrtMI

I have no clue about how to generate gcode files, so I just took the ones from the manufacturer CD.

Are there any gcode files I can download for correctly tuning and calibrating my printer. I would like to know that my hardware setup is right, before getting into the software stuff

Thanks.
Looks like you need to adjust the print bed level. When z=0, the nozzle should be 0.1mm above the printing surface - and that needs to be at every point of the printing area. Instructions on how to adjust this should come with your printer.

Essentially, the procedure is as follows (you should be able to issue these commands directly on your printer, so no gcode is needed):


auto home, i.e. all axes go to 0.
disable steppers, so you are able to move the print bed and the x-axis
put a sheet of paper on the print table. The thickness of ordinary paper is around 0.1mm, so that's good for calibrating.
now move the nozzle around the print bed. There should be a slight (!) friction between the paper and the nozzle and this friction should be the same everywhere. If not, use the screws on the four corners to adjust the level of the print bed. Do not attempt to fully correct any deviation at once, because this might bend the print bed. Make several rounds and adjust the screws by 1/2 turn only on each round. This is a tedious procedure but it is really required.


Finally, when the nozzle is at 0.1mm above the print bed in z=0, you should be able to print and the filament should adhere to the bed.

A heated bed also helps.

P.S.: For generating gcode files, you need a slicer. For the very first steps, I found Cura quite easy to use: you feed it with .stl files and it will slice it internally. Currently, I am using slic3r (and pronterface for controlling the printer itself).