The tool is used first to lower the height of the pedestal to where you want it.
Then the bottom is lowered, leaving a tendon in the center for support. The lathe is moving at about 600 rpm.
Scoop the wood out, reducing the size of the tenon and leaving a reasonable rim for the pedestal.
The pedestal needs to be inside or outside the screw holes for the faceplate. I havedecided for it to be outside.
Turn the wood away leaving the rim and tenon. Consider the shape of the rim and the depth of the rim keeping in mind the overall shape of the piece and the thickness of the bottom.