|You will make a drift. |
A drift is a punch used to finish a hole to the exact size and shape required. The lower end is tapered so it can be put into the punched hole. The middle part has a cross-section the same shape as the required hole and is at least 5cm long. The top end is also tapered, but rather more sharply so that it will knock out of the hole easily and not stick. The drift is made of hard steel so that it retains its shape.