With the countersunk screw hole you get about 10 degrees on the paddle, with that I'm able to leave the soundboard thicker. On the topside the paddle contacts the soundboard in the middle to start the high pitch then rolls on down and contacts the inside of the board for the low and raspy end of the yelp.
I love trying new things with my boxes. My failure pile is a lot bigger than my success pile, but this combo works real good. I've tried Walnut, Spalted pecan, and sycamore and they all sounded good IMO ! I even did a walnut with a 3/4 wide inside and it still had good rollover.
Thanks Steve