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B
FIG. 2
C
A
B
FIG. 3
operating direction. Use shim stock to insure no more than .005" (0.1mm) exists between gauge and casting or
between rod and throat plate, in both the operating and reverse directions of the handwheel. When this setting
has been made, tighten the three horizontal clamp screws (B, Fig. 3) securely, and recheck both clearance points
with .005" (0.1mm) shim gauge to assure no slippage occurred while tightening the screws.
SYNCHRONIZING NEEDLE AND LOOPER MOTIONS
NOTE:
Needle and looper mechanisms are carefully synchronized with
precision gauges before leaving the factory to insure the best possible
sewing conditions.
Should it become necessary to disassemble the main shaft or replace
components of the needle or looper drive mechanisms, re-synchroniza-
tion of the machine will be required to facilitate proper sewing adjust-
ments. This is accomplished by means of an adjustable split coupling
located beneath the rear top cover, connecting the crankshaft to the
main shaft, which in turn drives the looper mechanism.
To synchronize the machine, remove the needles, presser foot, throat
plate, feed dogs and upper feed roller mechanism. Rotate handwheel in
C
the operating direction until the needle bar is at the bottom of its stroke
E
and just begins its upward travel. Loosen screw (A, Fig. 2) and remove the
looper for the left hand needle from the looper holder. Insert a straight
D
steel rod (B) 5/32" (3.9mm) or 11/64" (4.3mm) diameter by 2-1/2" (63.5mm)
long into looper holder and retighten screw (A). It may be necessary to
reposition the looper holder so that the rod (B) will be in a vertical position
when at its farthest travel to the right. Rotate the handwheel until the rod
is at extreme left, reinstall the throat plate. Turn the handwheel in the
operating direction, with needle bar rising until rod (B) comes in contact
with the edge of the throat plate. At this point, clamp Union Special timing
gauge TT147 (C) around the needle bar (D), flush against the underside
of the machine casting (E). Rotate handwheel in the opposite direction
A
until either the gauge contacts the machine casting on the up stroke of
the needle bar or the rod contacts the edge of the throat plate. Maximum
allowable clearance between gauge and casting or rod and throat plate
is .005" (0.1mm)
If machine is not synchronized the following applies:
Both ends of the adjustable split coupling are secured to the crankshaft
and main shaft by spot screws and set screws. On the main shaft end of
the coupling (A, Fig. 3) three screws (B) thread horizontally through the
coupling. The holes in the main shaft end of the coupling are larger than
the diameter of the screws, permitting several degrees of rotation in either
direction to properly synchronize the needle and looper. Loosen the three
horizontal clamp screws (B, Fig. 3). With rod (B, Fig. 2) at its farthest position
to the left, snug the uppermost horizontal clamp screw enough to hold
coupling (A, Fig. 3) in position. If the handwheel is turned in reverse of
operating direction and gauge (C, Fig. 2) on needle bar (D) contacts the
machine casting (E) before rod (B) contacts the edge of the throat plate,
loosen horizontal clamp screw (B, Fig. 3) which was snug, while holding the
coupling in place with an Allen wrench in set screw (C). Rotate the
handwheel slightly in reverse of operating direction, snug the uppermost
horizontal clamp screw (B), recheck synchronization. If the handwheel
is turned in reverse of operating direction and the rod contacts the edge
of the throat plate before the clamp gauge contacts the machine
casting, adjust as before, except turn the handwheel slightly in the
10
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