Hi! My project is to print in 3D a clock mechanism in one shot and take advantage offered by 3D print to avoid assembling parts. However, an important question came to me: How much space to put between the gear and its axis?

I want the wheel to rotate easily around its axis and also minimizing the space between the two pieces. But the two parts must not be too close otherwise they will be stuck together.

I created a test board with several gears on Natural Shape. By varying the space between the wheel and its axis I want to detect the moment when both parts will be stuck together, or, when the wheel can no longer rotate around the axis.

The board I created have 9 wheels and the space between the wheels and the axis varies from 1mm to 0.1mm. The test was performed on the Cube2 printer at the FabLab with PLA. 

The wheel with 1mm have too much space around the axis (can be seen on the first picture), the wheel with 0.1 mm space is completely stuck and cannot rotate. The wheel with 0.2mm space can rotate but not easily, there is a lot of friction. So the best space between the wheel and its axis for my clock is about 0.3mm because the wheel turns without too much space. 
See you soon for the printing of the clock !