In this self project test, created a playmaker script that gets point of collision for the blade and then moves the particle to the contact point and sets the emitter to true.
I set up a wait variable that I call a "wait machine" that allows me to recheck collision every 1/10th of a second so that I can update the collision point in real time but not so much that it checks every frame and draws down performance.
My next test is setting up collision tags so that the saw can tell the difference between metal, wood, rock, etc and product the correct particle system.
Also working on texturing the saw blade after I get the script working with the tag system described above.