Yesterday evening I had a small part (might have outweighed a quarter) bolted to a 1x2x3 block on the Bridgeport. The fixturing proved inadequate it moved during the cut, mangling the work piece roughing up a parallel (I believe a 6" x 1-1/8" x 1/8") and wrecking a 1/2" end mill.
Moral of the story is that even small parts that will take only a small amount of milling warrant vigilant assessment of the fixturing arrangement.
The part I got right was (and what I teach regarding the mill): If general purpose milling is to be done, that doesn’t require a specific diameter end mill, always use the 1/2" because we have buckets of those.
The parallel has probably lost some parallelism and I have found that I can buy a replacement pair at MSC Direct.
Sorry about the mishap,
Bob