When the drill pinches and squeals on drilling through pieces of wrought iron and copper, and is liable to twist off before you get the job done, why don't you swedge it? Use a small hammer, and be careful not to chip the corner, as the drill is swedged cold.

Fig. 105 - A simple drill clearance.

Just touch the fluted part lightly on the emery wheel, bringing back a nice cutting edge and leaving the swedged corner projecting a little. The writer has used this little wrinkle for a number of years, and masters those stubborn pieces with ease.