How to make moving parts not stick together?
If parts stick together after printing, the positioning or extrusion is not working optimally.

This can be related to various issues:


Positioning of the head is not correct; this could be related to incorrect belt tension, incorrect steps per mm, streched belts.
The extrusion process is not working optimal; this could be related to over-extruding (incorrect steps per mm for the extruder, incorrect multiplier in the slicer, filament too hot) or the first layer height is incorrect (too low, so the lines spread out and tough each other). Extruder calibration is explained in more detail in this answer.


A very good start to verify what exactly your tolerance problem is is to print this tolerance test. Basically, these are diabolic shaped objects in a slightly larger outer shape object. Please slice this STL file with your favorite slicer to obtain the G-code for your printer. When the print is ready, you use a screwdriver to turn the diabolic shaped objects from large to small tolerance, the last one that does not turn is the maximum tolerance of your printer. So when printing in place hinges, you should use tolerance values higher than the one that did not turn.