Page 28
HQ Sweet Sixteen Service Manual
9. Adjustment of the Loop Lift and Needle Distance
Important Note: The timing and needle distance adjustment must
be done with the front machine cover on.
“Loop Lift” is a universal hook and timing term for all lock-stitch
sewing machines. When the needle lifts a specifi ed distance from
the
BDC (bottom dead center)
, the hook point is set to coincide
with the needle as shown in
(Figure 9.4.)
This is the radial posi-
tion of the hook called “Loop Lift”, commonly referred to as tim-
ing. Another part of timing is the “Needle Distance” This is the
axial distance from the hook point to the needle. Loop lift is the
radial setting of the hook and needle distance is the axial setting
of the hook. Both of these are set on the hook and fi xed with the
same set screws. Since two things are being set at the same time,
this can be a little diffi cult until practiced.
Tools required:
Loop lift clamp part #QM40199, 2.2
mm forked feeler gauge part #QM40136, 2 mm ball
end L Allen wrench, 2 mm handle Allen and a #3 fl at
screwdriver.
NOTE: The loop lift clamp used must have
a plastic protective compression pad, to avoid damaging
the coating on the needle bar.
Check. Observe the following:
• Remove the needle plate.
• Turn the hand wheel until the needle bar is at its low-
est position or
BDC
.
• Place the loop lift clamp (with special protective com-
pression pad) on the needle bar and set the thumbscrew
lightly.
• Place the 2.2 mm feeler gauge between the clamp and
the bottom of the head frame bearing surface
(Figure 9.1)
.
• Raise, reset and tighten the clamp, pinching the 2.2 feeler gauge
inbetween the clamp and projected bearing. This step may need
to be repeated a few times to remove all excess play between the
clamp and gauge.
• Remove the 2.2 feeler gauge
(Figure 9.2)
.
• Rotate the hand wheel
in the direction of motion
,
“This is very
important”
until the clamp lightly touches the gauging surface.
(Figure 9.3)
.
Important Note: If the hand wheel is turned too
hard, the clamp may move, making the check invalid.
• Check the position of the hook point relative to the needle.
(Figure 9.4)
.
• Check the distance between the needle and the hook point. It
should be as close as possible without touching. Ideally it will be
less than .001” gap between the two. Too much needle distance
or improper loop lift settings may cause shredding and skipped
stitches. Too little distance will cause the needle to bend during
sewing and cause other issues.
(Note: This is explained in more
detail on page 31.)
Figure 9.1
Figure 9.2
Figure 9.3
Figure 9.4
Loop lift and needle height both set correctly