(figure 4-9 [A]) to press against the back of its
opening. The bobbin-case opener moves the
bobbin case counterclockwise to allow the thread
to pass around the bobbin-case-opener lug. If the
opener is adjusted too tight, damage to many
parts may occur; and if the opener is not set tight
enough, extreme upper thread tension may be
necessary to lock the stitch properly. Adjusting
the bobbin-case opener is accomplished as
follows:
a. Turn the balance wheel toward the
operator until the bobbin-case-opener lever (figure
4-9 [C]) moves as far to the right as possible.
b. If the bobbin-case opener (figure 4-9
[D]) has been removed, reinstall it at this time.
Do not tighten the adjusting screw (figure 4-9 [E])
at this time.
c. Place two thicknesses of paper, as a
gauge, between the tip of the bobbin-case opener
and its projection on the bobbin case.
d. Move the bobbin-case opener right or
left as necessary to cause the bobbin case to move
as far to the right as possible without binding.
e. Tighten the bobbin-case-opener ad-
justing screw.
f. Turn the balance wheel toward the
o p e r a t o r a n d o b s e r v e t h e o p e r a t i o n o f t he
bobbin case and its opener. Ensure no binds are
present and that the bobbin case is pulled
counterclockwise as far as possible with each
rotation of the hook.
2. Adjusting the total relative lift of the
alternating pressers
The total relative lift of the alternating
pressers referred to here is that the feet lift
one-half inch at total lift. Maximum lift of the
alternating pressers is set to sew on heavier goods.
There are two types of adjustments, and either
type may be found on a given machine. The first
type of alternating presser (figure 4-10A) is usually
found on earlier sewing machines, while the
second type of alternating presser (figure 4-10B)
seems to be in current manufacture.
a. Adjusting the first type of alternating
presser is accomplished as follows:
(1) Turn the balance wheel toward the
operator until the presser-lifting eccentric lock
screw (figure 4-10A [A]) is visible inside the
opening at the back of the arm of the machine.
(See figure 4-11 [A], table 4-3, foldout at end of
this chapter.)
NOTE: Figure 4-10A shows two setscrews
(B). They are used to hold the presser-lifting
eccentric in place on the feed-driving rockshaft.
The adjusting screw is not visible in this figure.
(2) Loosen the lock screw and turn the
balance wheel until the adjusting screw is visible
in the opening in the back of the arm. (See figure
4-11 [A].)
(3) Turn the adjusting screw counter-
clockwise to obtain maximum total lift of the
pressers.
(4) Turn the balance wheel toward the
operator until the lock screw is visible in the
opening in the back of the arm and retighten the
lock screw.
b. Adjusting the second type of alternating
presser is accomplished as follows:
(1) Loosen the presser-lifting eccentric
adjusting wing nut (figure 4-10B [A]).
(2) Move the assembly up to decrease
the lift or down to increase the total lift of the
alternating pressers.
(3) Tighten the wing nut.
3. Adjusting the relative lift of the alternating
pressers
The alternating presser feet should each lift
t o a p p r o x i m a t e l y t h e s a m e h e i g h t . D o n ot
confuse relative lift with total lift. Here we are
adjusting the presser feet to lift to approximately
the same height. Adjusting the relative lift of the
alternating pressers is accomplished as follows:
a. Turn the balance wheel toward the
operator and observe the action of the alternating
pressers. If they do not lift equally, proceed to
step b.
b. Turn the balance wheel until the foot
that lifts too high is just above the throat plate.
c. Loosen the presser-lifting link crank
pinch screw (figure 4-11 [B]). The foot should
snap down; if it does not, push it down.
d. Tighten the presser-lifting link crank
pinch screw.
e. Repeat step a. If necessary repeat steps
b through d until the feet lift to the same height.
4. Adjusting the lifting linkage of the alter-
nating pressers
To set the lifting linkage, you must loosen
the lifting crank pinch screw (figure 4-11 [B]) and
4-9
