Easy to master work of a hand drill. Sometimes does not calculate SIPU and broke in half, still quite new drill. Of course, if broke off, not the whole working part, it can still be reground. But in any case, the cutting chip usually discarded. However, a simple tubular handle with a blind axial hole and a radial locking screw turn it into a useful tool. This countersink can make a small chamfer or to remove sharp edges in the holes of smaller diameter.
M. SHASHKIN, the city of Yakhroma, Moscow region