Tc 9-524 fundamentals of machine tools

Hand Die Threading on the Lathe
Die threading on a lathe is very similar to tapping on a lathe,
except that the die is aligned perpendicular to the work axis by
pressure exerted against the back surface of the die. This
pressure can be exerted by means of a drill pad, by using the
tailstock spindle, or by using the head of the drill chuck for
small dies. Die threading can be done using power or by hand,
using the same procedures as tapping. Power can be used to
remove the die from the work if the die stock handle is swung
to the opposite side and low reverse power is used. It is
difficult to cut very coarse threads with a die because of the
great amount of force needed to turn the die. It is advisable to
open up the die to its full width, rough-cut the threads, and
then close up the die and go over the threads for a finished
size. Always use a lubricant or coolant for this operation.
REAMING ON THE LATHE
Reamers are used to finish drilled holes or bores quickly and
accurately to a specified diameter. When a hole is to be
reamed, it must first be drilled or bored to within 0.004 to
0.012 inch of the finished size since the reamer is not designed
to remove much material.
Reaming with a Machine Reamer
The hole to be reamed with a machine reamer must be
drilled or bored to within 0.012 inch of the finished size so
that the machine reamer will only have to remove the cutter
bit marks.
The workpiece is mounted in a chuck at the headstock
spindle and the reamer is supported by the tailstock in one of
the methods described for holding a twist drill in the tailstock.
The lathe speed for machine reaming should be
approximately one-half that used for drilling.
Reaming with a Hand Reamer
The hole to be reamed by hand must be within 0.005 inch of
the required finished size.
The workpiece is mounted to the headstock spindle in a
chuck and the headstock spindle is locked after the piece is
accurately setup The hand reamer is mounted in an adjustable
tap and reamer wrench and supported with the tailstock center.
As the wrench is revolved by hand, the hand reamer is fed into
the hole simultaneously by turning the tailstock handwheel.
The reamer should be withdrawn from the hole carefully,
turning it in the same direction as when reaming. Never turn a
reamer backward. See Table 4-3 in Appendix A for the proper
cutting fluid for reaming. Never use power with a hand reamer
or the work could be ruined.