oh and if you want a good angle the trick is to use a rope or piece of string: have somebody hold it down in place and place the plywood so that the end of the rope (or string) starts from the bottom left or right hand corner. Then another person should move the string across the board with a pencil so that you get a perfect angle. Also the angle and height depends the distance from the start of the string (person holding it down) and the string moving across the plywood the height and angle