Space in plastic to fit a ball bearing?

[Magnethos]

I'm new in design and I'm designing a plastic piece where I want to fit a ball bearing.
The outer diameter of the ball bearing is 10 mm. If I want to fit it in the plastic. What measure I've to use in the plastic hole? 11 mm?

 

[AppleBite]

It all depends on the type of fit you are looking for, and the available tolerance for the drilling of the hole. If you are going for an interference fit, it's probably safe to assume that the plastic will be compliant enough for a less than 10mm hole (again, this all depends on the tolerance of the hole).

Also, remember that it's a lot easier to increase the diameter of a hole, than to try fixing a hole that is too wide. I'd start with a 9mm hole - test of fit - increase another 0.5mm - test for fit - and keep on with this until you have a snug interference fit.

And if all else fails, a little bit of glue is always allowable ;)