I ve got my Mendel Prusa i2 up and running after a few glitches. I dowloaded a simple test piece from thingiiverse and,fingers crossed, pressed print . The printer started up ok for the first 6 or 7 layers but then started to drift. The extruder moved out beyond the original footprint and naturally ended up making a messy blob. Can anyone suggest what is going wrong?

Check the axis in which the drifting occurred: belt tension, loose gear pulley, underpowered stepper, binding, etc.

The drift seemed to be mainly in the x axis. I checked the pulleys and they seemed to be ok. The x axis belt was loose so I tightened it. The cables from the hotend might have been fouling so I adjusted their position. Ill try again tomorrow and see how it goes. Thanks for the tips.