These are known as flycutters ---- you have to take a really light pass with them.
We had a bit about this on the wiki at:
Shapeoko CNC Router, Rigid, Accurate, Reliable, and Affordable (and I’ve added @fiero1’s link, so we have a circular reference and that is linked to from the Endmills page: Shapeoko CNC Router, Rigid, Accurate, Reliable, and Affordable for compleatness’ sake)
Since then, Carbide 3D has launched the McFly: