Mark the bevels on your edge with a Sharpie. Then make a light pass or two on the Sharpmaker's rods at the narrowest setting (30° 'back bevel'), and see where the ink comes off. If you see ink being removed at the edge itself, or (if you're really lucky) from the entire width of the bevel from edge to shoulder, your edge angle is equal to or less than 30° inclusive, and you're in good shape to use the 30° setting to resharpen it. If you see the ink being scrubbed off high on the bevels or at the shoulders of the bevels, but not at the edge, that indicates your edge angle is wider than the rods' current setting at 30°. Re-mark the bevels and try the same test at the 40° setting, and look again to see where the ink comes off. At the very least, it should be coming off closer to the edge. If the ink still isn't coming off at the edge itself, and only somewhere above the edge, that shows your blade's edge angle is wider than 40°; if, so, you'll need to do some more grinding/thinning of the edge profile to get it within the limits of the Sharpmaker. Just looking at your picture and estimating, your edge angle doesn't look too wide to me; I'd guess you're already at least within the 40° limit, and maybe near to or within the 30° limit.
David
