I currently have two 3D printers, a Geeetech Prusa i3 Pro B and the Tevo Black Widow. Both these are excellent printer but occasionally things can go wrong. I was trying to print a .STL of a Terminator Genisys Skull on the Geeetech and it all went a bit wrong. The bearing that guides the Y-Axis belt collapsed, causing a lot of skipping on the Y-Axis while the printer was trying to print. The results can be seen in the video below.