At the power levels you are aiming for, just holding the teeth on to the bar with screws is not enough, the screws will likely shear off after just a few hits. The teeth need to lock into the bar to keep it securely attached; I use a T shaped lock, while NST uses a dovetail shape:



The the dovetail method is arguably more secure, while my method allows lower accuracy machining. Either way, you need to recess the screw heads to stop them being sheared off and use the largest possible size; probably a couple of M12 in this case.