The plainer he has is a Straight-o-Plainer & they are incredible I guess now they cost between 60k -70k. He measures the cup in the board sets the bottom head to that amount. Then the top to your desired thickness and runs it through. The straight-o-plainer has spring loaded fingers that hold the board down but doesnt flatten it, while the bottom head cuts the wood then it goes through the top head that cuts it down to the thickness you set
I'm here to learn about CNC routing & anything else I can pick up.