Question about Bearings?

[MrForbes]

In automotive engines, most overhead camshafts ride directly in holes in the aluminum head, and the aluminum lasts for a long, long time. The trick? lubrication. Since you can't have oil dripping from your robot, you probably need a bushing or bearing. Which you use probably depends on load, speed, thickness of the mounting surface, and other stuff that we don't know, but you do know.

[Justin Stiltner]

IGUS makes some really nice bushings for small holes like this.
You would most likely want a flanged plain bearing. Or McMaster sells plastic and bronze bushings either of which would work, and be lighter than a ball bearing.

[Dick Linn]

While you might be able to get by with a plain hole (if properly dimensioned and finished), you'd be well advised to consider an oil-impregnated bronze bearing. They are very inexpensive in the small sizes - well under a dollar. There are a number of 1/4" inside diameter bearings of varying lengths for 50 to 75 cents each here:

http://www1.mscdirect.com/CGI/NNPDFF?PMPAGE=3670