Hi all, I am involved in a project called F1 in schools-there have been previous threads on this forum. Basically we need to design and make using CAD/CAM a model car, which is powered by a CO2 cylinder. The time taken to cover a 20 meter track is recorded. I'm having some problems deciding what is the best fit for the bearings to fit the housing as well as the wheel shaft. The recommendation seems to be a 'press fit', but what would be the difference in dimensions to design in, with regard to the housing diameter versus the bearing outer diameter, and with regard to the shaft diameter versus the bearing inner diameter? I am thinking of using ABS/Acetal for the housing, and Acetal for the shaft. Since the car is powered by the discharge of CO2 rather than the wheels, the bearing loads are going to be low. Thanks in advance!