First time here. I have been looking at 3D printers for a while. Yesterday, I bought the PowerSpec Ultra 3D printer which I think is a clone of Makerbot 3D printer. It took me about two hours to assemble the 3D printer - attach the dual extruders to the top carriage, attach the door to the cabinet, and assemble the top cover. The filament was missing from two boxes packed under the bed. After installing the software and leveling the bed, I printed a 20mm x 20mm box using ABS filament and I noticed some shrinking in the middle of the box. I tried to print a robot's head and I thought something went wrong with the printer. The top carriage stopped short at the front and I found out that a clip that tensions the belt was in a wrong position so I moved it to correct position. I printed a tube squeezer and it worked. Any suggestions for best operation of the printer and the best filament?

http://www.microcenter.com/product/4...tra_3D_Printer