TM 9-3419-234-14&P
(3) The correct thread length is determined by measuring
(2) To disengage the clutch when standing in a position
from the first full tooth of the chaser back to the land of
to make a speed change, throw the clutch lever to the
the reamer (die head closed).
farthest point away from the operator To engage the
clutch, simply pull the lever to the left of the machine until
(4) Adjustment to the reamer to obtain correct thread
spindles are set in motion.
length is made through the adjusting tube, Figure 3.
First, release the clamping rod and rotate the adjusting
(3) The clutch may also be used to jog the machine,
tube, moving the reamer forward to decrease thread
however, it is not as infinite as when using the Start-Stop
length or rearward to increase thread length.
push button control station.
(5) If adjustments are correctly made, the die head will
h. Carriage
trip open Immediately upon completion of the desired
(1) Carriage traverse on 12C, 16C and 20C Machines is
thread length.
obtained through two mediums, a rack and pinion
d. Die Head
carriage, Figure 18, Page 19, and a leadscrew carriage
For instructions pertaining to the servicing and
Figure 20, Page 20.
maintenance of Threading Heads refer to Chapter 2 Page
(2) Non-leadscrew machines incorporate the rack and
26 covering Heat Treated Threading Heads.
pinion carriage which is advanced by means of a carriage
operating handwheel #183, Figure 18, Page 19.
e. Spindle Reverse
Depending on the bed of the machine, carriage travel
(1)
All machines, single spindle, double spindle,
(maximum thread length) of 13 1/2", 24" and 36" can be
leadscrew and non-leadscrew are designed for both right
obtained. Workpieces requiring threads longer than the
and left hand threading.
standard carriage travel can be produced by regripping
(2) These machines may be equipped for left hand
the workpiece and passing it through the bore of the die
threading by incorporating a reversing push button control
head.
station offered as auxiliary equipment. By placing the
(3) A leadscrew carriage is advanced by depressing a
START button in the position marked LEFT the spindles
handle #195, Figure 13, Page 15. This action engages
will revolve in the direction for cutting left hand threads.
the leadscrew nuts with the leadscrew to propel the
(3) Double spindle leadscrew machines incorporate a
carriage at a controlled rate It is sometimes necessary to
mechanical reversing mechanism, supplied as standard
move the carriage slightly so the leadscrew nuts will
equipment, of facilitate left hand threading. The reversing
mesh with the leadscrew.
mechanism can also be equipped to non-leadscrew
(4) The leadscrew is tripped open, which stops the
double spindle machines but is available as auxiliary
forward travel of the carriage, automatically as described
equipment only.
under Die Head and Leadscrew Trip Mechanism. The
(4) With the reversing mechanism, only the right hand
leadscrew can also be tripped manually by lifting the
spindle revolves for left hand threading while the left hand
leadscrew operating handle.
spindle revolves for right hand threading. Thus, a
(5) 10C and 16C Pipe and Nipple Threading Machines
workpiece requiring both right and left hand threads can
incorporate a lever operated carriage, Figure 17, Page
be threaded on one machine.
18, and propelled by a carriage operating handle #225,
CAUTION Do not attempt to change the direction of
Figure 17, Page 18. The handle is placed at a convenient
rotation of the spindles while-they are in motion.
position for operating ease and Is adjustable to eliminate
f. Headstock
unnecessary carriage travel when cutting short thread
lengths or on high production runs.
enclosed in an oil tight gearbox located on the headstock.
(6) To reposition the carriage along the bedways, lift the
All machines incorporate 8 spindle speeds as standard
operating bar, #10, Figure 17, Page 18, and move the
equipment. With these 8 speeds, all diameters within the
carriage along the bedways until one of the notches on
ranges of the machines can be threaded at the most
the operating bar falls onto the operating arm stud #224,
efficient speed.
Figure 17, Page 18.
(2) To obtain anyone of the spindle speeds available on
i. Leadscrew
these machines simply refer to the speed range chart
(1) When setting up a machine equipped with leadscrew
located on top of the headstock. This chart shows the
feed, the only operation necessary is to place the correct
positions the gear shift levers #85, Figure 15, Page 16,
leadscrew change gears in place. A gear table is
must begin to obtain a certain spindle speed.
mounted on the inside of the gear box cover, #237,
(3) Special higher and lower speeds are available,
Figure 13, Page 15, which lists the proper gears to be
however, they must be incorporated during the course of
used for any pitch of thread within the range of the
the machine's construction.
machine. Charts on the gear table also show the method
g. Clutch
for gearing the leadscrew for right and left hand work with
either straight or compound gearing.
clutch which is operated by a clutch lever #99, Figure 13,
Page 15 The clutch may be disengaged when a change
in speed is being made instead of shutting off the
machine.
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