What is the difference between a cake board and a drum board? I don't use the cardboard cake boards, I use the harder and thicker ones that are covered in foul (made of wood maybe?).
I definitely get ridges in the bc were I stop and start with the scraper, but around the edges of the cake board the foil is folded under so the edges of the board aren't smooth. This creates ridges too.
I think you are using a drum board then. Cake boards are just the flimsy cardboards. The harder and thicker ones covered in foil are cake drums. People use a cardboard under the cake, and then a cake drum to sit it on (that you can cover and decorate with fondant).
I think your "ridges" are because you start and stop with the scraper. What you can see people doing is to hold your scraper at a starting point, put your left hand right there on the wheel and in one single motion, without stopping, turn the wheel and get to the beginning point.