[asid61]

We use bearing blocks for slots or other moving connections. Otherwise we just use plates with mounting holes, or bore directly into aluminum box tubing when it's applicable.
It really depends on the application.
We generally aim for a 1.124" or 1.123" hole (the latter for undersized measurements on bearings) by boring it out on the Bridgeport mill, manually. It's arduous but generally only takes around 5-6 minutes with an experienced student. I dream of one day having a 1.124" reamer and 1-7/64" drill bit to do bearing bores. We could go to 1.125", a regular size, but then we'd probably have to locktite it.