Maybe you need to enlarge a hole, or make a dead-on round hole larger than your largest Forstner bit.
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WD324959

Maybe you need to enlarge a hole, or make a dead-on round hole larger than your largest Forstner bit. Do either using a rabbeting and a flush-trim bit. To enlarge a hole's radius by 14 ", first rout a 14 "-deep rabbet the width of your cutter while keeping the bearing against the edge of the hole. This creates the "step."

Next, turn the workpiece upside down and install a flush-trim bit. Adjust the cutting depth so the bearing rides along the cut made by the rabbeting bit and rout away the step.