1. Mechanical Engineering Technology
External Screw Thread Cutting
Objectives: Students should be able to:
• Define external screw thread.
• State and explain the uses of Dies and the tools
used for holding them.
• State precautions associated with external screw
thread cutting.
2. Hand Threading Safety
• When using the tap or die use compressed air to clean the
piece that you are threading.
• Chips from the work can be sharp so use a brush to
remove them.
• Wash hands after using cutting fluid because it can cause
skin disorder.
• Be sure that die is securely clamped in the die stock
because it can fall and cause painful injuries.
• Be careful when handling broken taps because they have
sharp edges.
3. Cutting External Threads
Dies are used to cut external threads by
hand. Solid Dies, are not adjustable and for
that reason are seldom used. The Adjustable
Round Die, are the most widely used die for
hand use.
The latter has a wide range of adjustments
and is fitted with guides to keep it true. Dies
are available for cutting most standard
Threads.
8. EXTERNAL SCREW THREAD CUTTING
STEPS
1. Material size must be equal to the outside diameter
of the thread.
2. Chamfer the end of the metal.
3. Clamp work securely in bench vice, level and square.
4. Make clockwise turns to start the threads and anti-
clockwise turns to break the chip
5. Oil must be used to lubricate the threads.
