We would love to think that miter saws direct from the factory are cutting square and true. That is often not true, or they can get out of square with use and abuse - even by simply being dusty in the wrong places.
This video shows the techniques for setting the blade square to the table and square to the fence. Most importantly it shows you how to make and use the very simple disposable jig that will get the saw square to twice the distance it is capable of cutting!
Learning Curve 144