on plunging... dont. any vibration from plunging seems to damage caribe end mills and most of these small bench mills have plenty of give in the head to cause this. its best to ramp or helix into a cut (on any machine really) at about 30-50% of your normal feed rate. you can also get a tool with a small radius on the tops, which will reduce chatter and the likelyhood of breaking the bit. if helixing isnt an option due to cam abilities, you could drill a pilot with a larger bit than your end mill and start from there.