I need to countersink a 1/2" lag plus washer going in at a 45* angle. With the washer on it needs to be 1-1/2 wide. I tried to use a spade bit and go in at a 45* angle and I almost had a serious injury, the bit spun right off the wood catching my shirt and winding up 
Any idea how I can do this safely?
Any idea how I can do this safely?