The wood block grain can sometimes be fairly frustrated when you try to be as precise as possible. With a little of mis-forced on your knife, the fine edge chipped away fairly quickly. But working image in an abstract form can turn this toward your advantage. I kind of like the pattern on Mahogany and you can work with those line as vertical or speedy elements as in your image. Anyway, the bottom line is: You just carve on to these blocks and forget the finicky detail you have on your paper, its kind of fun this way to play w/ your block.