Took all night to make 2 holes. Needed to work back and forth between front and aft, using long tapered files if needed to steer hole. Would file in direction of desire, then spin file CCW to make hole again round. If hole was OK located, would use a Unibit step drill to go to next size.
You can see here hole is almost there, need to move hole just slightly down, (see the scrape of Prussian blue).
Y9-10-09