Answer Happy

1. Name the tools used to make the following holes and sketch and describe the important features of their cutting parts: a) a 5 mm diameter hole in mild steel, b) holes drilled in the ends of a mild steel bar in preparation for centre turning, 2. Use sketches and notes to illustrate: a) the mechanism for raising and lowering the spindle of a sensitive drilling machine. b) the provision made in the spindle for removing the drill chuck and its method of removal. 3. Most drilling machines can operate at different speeds. How is this done and why is it essential? 4. a) b) In what circumstances would you use a reamer? Why does a twist drill sometimes become "blued" when in use? 5. Why must a centre punch be used before drilling? 6. What is the general rule for choosing drill speeds for different sized holes?