Singer 66 Series User manual

SERVICE MANUAL
FOR
SINGER SEWING MACHINES
Classes 66, 99, and 185

Disassembling Numbered Thread Tension Assembly
Turn the thumb nut (B, Fig. 1a) to the left until the numeral “0” on the
numbered dial stops opposite the center line between the plus and minus
signs. Press in the dial to disengage the pin (C) in the thumb nut from the dial,
and remove the thumb nut and dial, stop washer (E), tension spring (F),
indicator (G), the two tension discs (L), and the thread take-up spring (N).
Fig 1a.
Reassembling Numbered Needle Thread Tension Assembly
First, make sure that the tension spring (J, Fig. 1b) is in place in the stud
(O), then place the thread take-up spring on the stud, having the tail (inside
the coil) of this spring in one of the grooves (T) of the stud, and with the large
loop (N) of the spring resting against the upper end of the recess at (M, Fig 1a).
Fig. 1a shows the spring in the correct position on the stud. The tail of the
spring is not visible in these illustrations, but its location inside the spring coil
is indicated in Fig. 1a by (K).
Fig. 1b
Place the two tension discs (L, Fig.1c) with their flat thread-bearing sides
together in position on the stud (O) and with the loop (N) of the thread take-up
spring straddling the discs (L) as shown in Fig.1c.

Fig. 1c
Next, replace the indicator (G) with the large open side facing the end of the
stud and so that the plus and minus marks will be at the top with the minus
sign to the left. Then insert the tension spring (F) in the indicator with the first
(half) coil of the spring straddling the lower half of the stud as shown in Fig. 1d.
Place the stop washer (E) on the stud so that the extension will be above the
tension stud.
Fig. 1d

To Adjust the Thread Take-Up Spring
The thread take-up spring (T, Fig. 9) should be set so that when the eye of
the needle reaches the goods on the downward stroke of the needle bar, the
spring will be through acting and will rest against the stop on the thread take-
up spring regulator (U, Fig. 9). If the thread take-up spring is not correctly set,
loosen the set screw (R, Fig. 9) in the arm of the machine and turn the tension
stud (S, Fig. 9) to the right for more movement of the spring or to the left for
less movement. When the spring is correctly set, securely tighten the set screw
(R).
The tension on the thread take-up spring should be just sufficient to take up
the slack of the needle thread until the eye of the needle reaches the goods on
its decent.
To increase the tension on the thread take-up spring (T), loosen the tension
screw stud (S) and force the take-up spring from the recess in the regulator (U)
to the right between the regulator and the tension discs until the required
tension is obtained, then securely tighten the tension screw stud and force the
spring back into its position in the regulator recess. To decrease the tension,
force the spring to the left between the regulator and the tension discs.

Remove and Replace the Oscillating Hook Slide
To remove the oscillating hook slide (B, Fig.2) from the machine, raise the
needle to its highest point and draw the slide plate slightly to the left, then lift
the right hand end and draw it toward the needle until it is disengaged from
the spring (A, Fig. 2) in the bed of the machine.
To replace the slide plate, slip it into the slideway from the throat plate end,
as shown in Fig. 2, being careful to see that both ends of the spring (A) enter
the grooves on the underside of the slide plate.

To Remove the Bobbin Case
(Operator being at the front of the machine)
Raise the needle to its highest point and remove the oscillating hook slide as
instructed above. Insert the nail of the forefinger of the left hand under the
latch (C, Fig. 3) and raise the latch just high enough to clear the edge at D, Fig.
3, then move it toward you.
Under no circumstances must the screw (E, Fig 3) be loosened for the
purpose of removing the bobbin case, as loosening the screw will bring the
bobbin case out of location and cause difficulty in the stitching operation.
(For instructions for adjusting bobbin case position bracket, see page 8.
Hold the bobbin case between the forefinger and thumb of the left hand, as
shown in Fig. 4. Tilt the bobbin case to the left and at the same time slightly
turn the right or forked end toward you so that it is moved out of engagement
with the sewing hook. Then tilt the bobbin case toward the right and remove
it. (See Fig. 4).

To Replace the Bobbin Case
(Operator being at the front of the machine)
Hold the bobbin case between the forefinger and thumb of the left hand, as
shown in Fig. 4. Insert the forked end of the bobbin case under the throat
plate so that the fork straddles the position stud (F, Fig. 5). Then with a slight
twisting motion of the fork to the left and to the back, lightly press the bobbin
case downward until the edge of the sewing hook engages in the groove under
the rim of the bobbin case.
Having set the bobbin case into the correct position, lock the latch (C, Fig. 5)
in the notch (D, Fig.5) to hold the bobbin case in place. Then replace the slide
from the right as shown in Fig. 2.

To Adjust the Bobbin Case Position Bracket
If for any reason it becomes necessary to adjust the bobbin case position
bracket to obtain the proper thread space between the bobbin case and the
bobbin case bracket, loosen the screw (E, Fig. 3) and move the bracket until
there is between .010 to .015 of an inch space at the heel of the bobbin case
and the cushion spring, then securely tighten the screw (E, Fig. 3).

To Set the Needle Bar at the Correct Height
See that the needle is pushed up into the needle bar as far as it will go.
Also see that the timing gauge (H, Fig. 6) is set at the correct height by
having the top of the finger of the timing gauge centered on the upper timing
mark on the needle bar connecting stud (G, Fig. 6) when the stud is at its
lowest point as instructed on page 6.
Then turn the balance wheel over toward you until the lower timing mark on
the needle bar connecting stud (G, Fig. 7) is centered on the top of the finger of
the timing gauge (H, Fig. 7) on the upward stroke of the needle bar. When the
needle bar connecting stud is in this position, the needle bar should be set so
that the top of the eye of the needle will be about 1.16 inch below the point of
the sewing hook.
In case the needle bar is not set at the correct height, loosen the screw (Q,
Fig. 9) in the lower end of the needle bar connecting link (K, Fig. 7). This screw
can be reached when the needle bar is at its lowest point by inserting a
screwdriver through the hole provided for this purpose in the arm. After
loosening this screw, move the needle bar up or down in the needle bar
connecting stud until it is at the correct height as instructed above, then
securely tighten the screw (Q) in the needle bar connecting link.