You often don't notice until it's too late. After repeatedly raising and lowering the blade of your radial-arm saw, you've cut a deep kerf into the top of the table and practically ruined it. Solution?
Save Saw Table

Before you chew up your table, lower the blade to the correct depth, about 18 " below the surface of the table. Then, tape a wooden block to the column of your radial-arm saw as shown in the drawing at top. Now, whenever you raise and lower the blade, the block will prevent the blade from digging deeper into the table.
—from the WOOD® magazine shop