Step 4: Rotary planer
On the right front side of the work piece you can see something blue in color pushed under the corner of the work piece. This is a piece of cardboard from a 12 pack of canned soft drink. When I pressed on the corners of the work piece I discovered this corner rises up from the work table. I folded a piece of thin cardboard and pushed it under the corner as a shim until the work piece could not be rocked. Then I began making light cuts with the rotary planer while holding the work piece down firmly. After each cut I moved the saw arm, locked it down, and pulled the planer over the workpiece again. This process will shoot a relatively flat and true surface on the top of the work piece. The rotary planer does leave marks and swirls that will need to be removed later.