Page 87 - Turner 1st sem Practicals

Job sequence

TASK 1 : Truing of round rod

• Clean the machine and check before working. • Repeat until the gap is the same.
• Position the four jaws of the independent chuck, • Repeat the above sequence for other set of opposite
equidistant from the centre to hold the work. jaws.
• Tighten the two adjacent jaws, enough to grip the work. • Bring the pointer tip closer to the work.
• Place the surface gauge on the bed ways close to the • Rotate the chuck by hand and observe the gap.
work.
• Engage the spindle lever at about 250 rpm and run the
• Adjust the pointer to make its tip move close to the top machine.
side portion of the work maximum gap.
• Give slight pressure on the top of the tip to touch the
• Rotate the chuck-by hand and observe the gap between work and feel.
the pointer and work surface for the position of the two • If the feel conducting the pointer tip is uniform it
opposite jaws.
indicates that the work is trued.
• Open the jaw slightly when the gap is more and tighten
the opposite jaw.

TASK 2 and TASK 3: Truing work in four jaw chuck square rod and hexagon rod

• Clean the machine and check before working. • Open the two jaws slightly when the gap is more and
• Position the four jaw of the independent chuck tighten the opposite two jaws.
equidistant from the centre. • Repeat until the gap is the same.
• Open the adjacent jaws sufficiently enough to insert the • Repeat the above sequence for the set of opposite jaws.
work and place the work inside the chuck.
• Bring the pointer tip closer to the work corner.
• Tighten the two adjacent jaw, enough to grip the work.
• Rotate the chuck by hand and observe the gap.
• Place the surface gauge on the bed ways close to the • Engage the spindle lever at about 250 rpm and run the
chuck.
machine.
• Adjust the pointer to make its tip move close to the top
side corner of the square rod a maximum gap. • Give slight pressure on the top of the tip to touch the
work corner and feel.
• Rotate the chuck by hand and observe the gap between
the pointer and work corner for the position of the two • If the feel of conducting the pointer tip is uniform in each
opposite jaws. corner, it indicates that the work is trued.

Skill sequence

Truing work in a four jaw chuck with the help of a surface gauge

Objective: This shall help you to
• true a round, square and hexagonal in a four jaw independent chuck with the help of a surface gauge.
If truing is not done before turning, the following will be the Measure the job size with an outside caliper or with a steel
results. rule. (Fig 1)
Uneven load on the cutting tool. Position the four jaws of the independent chuck, equidis-
tant from the centre. The distance between the inner face
For the same depth more metal will be removed from the
out of centre portion. of the opposite jaws is equal to the diameter of the work.
(Fig 2)
Surface turned may not be cylindrical.
Open the adjacent jaws sufficiently enough to insert the
Sequence during truing work. (Fig 3)
Keep the main spindle in a neutral position.

Producltion & Manufacturing : Turner - Exercise 1.3.25 75