LATHE OPERATIONS - OD1645 - LESSON 1/TASK 1
(2) Mounting the Workpiece For Facing. The workpiece to be faced may be
mounted between centers or in a lathe chuck. If the right end of the piece
is to be faced and the piece is to be mounted between centers, a half-center
is often used in the tailstock spindle.
The half-center permits complete
facing to the center hole without interference with the center.
piece mounted between centers, the left end cannot be faced if a lathe dog
is used. It is advisable to reverse the piece for this operation.
(3) Proper Cutter Bit For Facing.
The right-hand facing cutter bit is
used for facing the right end of the workpiece and for shoulders which face
to the right. The left-hand facing cutter bit is used for facing the left
end of the workpiece and for shoulders which face to the left.
(4) Position of The Cutter Bit For Facing. With the cutter bit positioned
in the cutting toolholder, fasten the holder to the toolpost (figure 25 on
Carefully adjust the holder so the cutting edge of the bit is
exactly on the horizontal centerline of the workpiece. If the cutting edge
is not on center, the end cannot be faced to the center of the piece and the
rake and clearance angles will not be correct. Adjust the cutting edge of
the cutter bit to a slight angle to the workpiece surface by adjusting the
compound rest of the lathe.
(5) Facing Operation. For the first or roughing cut, set the cutter bit,
subparagraph (4) above, and begin the cut as close as possible to the axis
of the workpiece, feeding the bit outward, away from the axis (figure 25).
Remove only enough metal to square the end over its entire surface. If the
piece must be faced to a specific length, take two or more roughing cuts in
the same manner, leaving a small amount of metal to be removed for the
finishing cut. For the finishing cut, readjust the bit so that the cutting
edge is set nearly flat against the workpiece surface, removing only a
light, thin chip. The finishing can be taken in either direction, from the
axis outward as in the roughing cut, or from the circumference of the
workpiece inward toward the axis. In facing, care is needed to see that the
bit does not contact the tailstock center.