Page 120 - CITS - Fitter Trade Pactical - Volume - 2

FITTER - CITS

EXERCISE 35: Care & Maintenance while using Taps and

Dies

Objectives

At the end of this exercise you shall be able to
• identify correct method of tapping.
• perform proper procedure while using die.
• understand causes of broken tap during tapping
• achieve high quality external and internal thread.

Following key points are covered while using tap and die for making internal
and external thread.

• Hole size for tapping is very crucial, it must be correct in size and chamfered.
• Hole size may be find as
Hole size = Tap size - 2 x depth of thread
• Do not forget to give the chamfer required for aligning and starting the tap

• Hold the work firmly and horizontally in the vice. The top surface should
be slightly above the level of the vice jaws . this help in using try square
without any obstruction while aligning the tap.

• Fix the taper tap in Tap wrench.
Too small wrench will need a greater force to turn the tap . very large and
heavy tap wrenches will not give the feel required to turn the tap slowly as it
cuts.

105

CITS : CG & M - Fitter - Exercise 34