Drills

1. Redraw the twist and label all parts.

2. What are twist drill made from?
Twist drill are made from either high carbon steel or high speed steel. 

3. List the 4 points needed for a correctly ground drill.
The 4 points needed for a correctly ground drill are
a. Point should be central
b. Lips should be equal length and at correct angle
c. Correct lip or side clearance is essential
d. Check for overhead or burnt edges

4. What lubricant is required for mild steel and aluminium?
The lubricant that is required for mild steel is SOLUBLE OIL and the lubricant that is required for aluminium is KEROSENE.

5. How are drills identified?
Drills are identified by the diameter of the hole that they cut.

6. Draw a morse taper drill shank. 

7. What is countersink drill used for?
Countersink is used when screwheads or rivets must be set below the surface of work.

8. Redraw the countersink drill and the hole it drills.

9. Describe the steps needed when drilling large holes or drilling accurately.
Lay out as for general hole drilling. Then scribe a witness circle of the exact diameter of the drill from the marked centre. Don't punch where the centre lines intersect the circle. This will provide witness or check points both during and after drilling the hole.

10. Redraw the diagram showing marking out for a general hole.