Activity #9
Name: Rench Juben M. Apuntar
Course: Basic Workshop and Machining
Year/section: MexE-3101
Date: 22/11/2020
Review questions
1. What is the purpose of the thread-cutting dial during screw-cutting?
The thread dial is mounted on a spindle at the opposite end of which gear in
mesh with the lead screw to achieve the accuracy of engagement of the split nut on the
lead screw for each cut. Due to this, the screw will travel along the same path as the
previous cut.
2. Name two pieces of equipment used to prevent long slender workpieces flexing during
machining on a center lathe.
To counter long slender workpieces flexing during machining on a center lathe, a
two-point travelling steady and three-point fixed steady are clamped in the machine
bed.
3. What is a mandrel used for?
A mandrel is used to mount workpiece which has a finished bore and requires
the outside to be turned concentric to it. It is placed between centers and the work is
machined already described for between-centers work.
4. State the two important capacities of a center lathe.
Center lathes are used to manufacture cylindrical shapes from range of materials
including steels and plastics. Two of its important capacities are the largest diameter
which can be rotated over the bed of the machine known as the swing and the maximum
length of workpiece which can be held between the centers of the machine.
5. What is the purpose of using a center drill?
The purpose of a center drill is to produce centers in a workpiece for turning
between centers. It provides a suitable guide to start the drill in the center of the bar and
are available in various sizes.
6. Name four types of work holding equipment used on a center lathe.
Work holding equipment are used to hold workpieces in a center lathe. Types of
work holding equipment includes chuck, faceplate, chuck keys and centers.
7. Why is it essential to have the cutting tool set at the center height of the workpiece?
It is essential to have cutting tool set at the center height of the workpiece
because tool set too high can reduce the clearance and will rub, while tool set too low
decreases the rake angle. Setting the cutting toll right at the center of the workpiece will
give the right measurements for rake and clearance angle resulting to best finish.
8. Give two reasons why a boring operation would be carried out on a center lathe.
Boring is the process of enlarging the hole that has already been drilled. It can be
performed through center lathe because boring is used to achieve greater accuracy of
the diameter of hole and can be used to cut a tapered hole. Also, boring can be viewed
as the internal diameter counterpart to turning, which cuts external diameter.
9. Why is it necessary to have a direct relationship between rotation of the work and the
longitudinal movement of the tool during screw-cutting?
Longitudinal feed is the movement of the cutting tool parallel to the axis of the
workpiece. A direct relationship between rotation of the work and the longitudinal
movement of the tool during screw-cutting to cut an accurate thread.
10. Describe three methods used to turn a taper.
Taper turning means to provide a conical surface by gradual reduction or
increase in diameter from a cylindrical workpiece. The three common methods used to
turn taper are with a form tool, with a top or compound slide and with a taper-turning
attachment. In using form tool, a form tool is set to the work at half taper angle and is fed
straight into the work to generate a tapered surface. It is used in turning short length of
taper. The method with a top or compound slide employs the principle of turning taper by
rotating the workpiece on the lathe axis and feeding the tool at an angle to the axis of
rotation of the workpiece.
