Facing Operation

Lathe Operations
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57

With the

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

page 59).

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.