Ok I went 13” pretty much parallel from center of the bow and then straight Pyrimid from there to tips. I have found its best for me to finish flipping the tips after I’ve flattened the back as best as possible and got most left and right crooks from the stave blank.this stave had some areas on the back that was concaved. I managed to get most all of this out. But I will be careful during the tiller stage not to hinge these areas.