Singer 206K25, 206K43, 306, 319, and 401 Service — Service manual — PDF Download

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Form 20732
            Printer in ll S A

       SERVICE MANUAL
                     FOR
      SINGER
        SWING-NEEDLE
     SEWING MACHINES

      FOR COMBINED STRAIGHT AND ZIGZAG STITCHING
                   REVERSIBLE FEED




                        "SINGER S





                                   Machine 306w25


                               See Index on pages 169 to 174

THE SINGER MANUFACTURING COMPANY

        *A Trademark of THE SINGER MANUFACTURING COMPANY


                                                          Insert in place of Corresponding Sheet in Form 20732 (257)

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PROPERTY OF

        THE SINGER MANUFACTURING COMPANY



This is a private and confidential communication to and for the use of only

the employees of The Singer Manufacturing Company and its affiliated com-

panies. Reproduction, sale, distribution, or publication thereof to the public

is forbidden.

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TABLE OF CONTENTS



                                                           Pace
 SINGER Automatic Swing-Needle Sewing Machines ........             3 to 79

 SINGER Non-Automatic Swing-Needle Sewing Machines of Class 306 and
     Machine 206K43                                                   81 to 85

 SINGER Non-Automatic Swing-Needle Sewing Machine 206K25        87 to 102

 SINGER Automatic Swing-Needle Sewing Machines of Class 319       ..103 to 123

 SINGER Automatic Swing-Needle Sewing Machines of Class 401           ..125 to 162

  Descriptions of Machines ......                                            ....163 to 168
Index                                                   169 to 174





SINGER AUTOMATIC SWING-NEEDLE
          MACHINES

  The instructions on the following pages, up to and includ
ing page 79, apply to 306 Automatic Swing- Needle Machines.

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TiPS ON SETTING UP

After removing the machine from its packing case, 6. By means of an oil can filled with Varsol,
set it up in the order noted below. flood the sewing hook assembly. Run ma-
chine for about three to five minutes until 1. Inspect for concealed damage incurred
all the tacky oil is washed out. Then ap- during transit, typical forms of which are
ply SINGER Oil and run-in the machine as follows:
again for three to five minutes.
Bent arm shaft.
Broken or bent hand wheel. 7. Oil the sewing machine completely. See pages
74 to 77. Wipe away all surplus oil. Cracked or bent bed.

Noisy gears (high pitched whining gear tone as 8. Make sure there is heat expansion clearance
well as gear growl) caused by severe shock. .015 to .020 inch between rear arm shaft bush-
Machine bound tight by severe shock. ing and flanged bushing. See page 27.

Broken or bent under-bed parts.
9. Inspect condition of needle before making sew-
Broken or cracked motor end covers, light and ing test. See page 5. Check hook and needle
pulley. relationship.
Broken or bent stitch regulator lever.
10. Sew-in the machine and check the stitching for Water damage (observe for water marks inside
correct behavior of bight controls and pendulum carton).
motion. See pages 52 to 55.
2. Turn hand wheel over toward you to make cer-
tain that sewing mechanism turns freely. 11. Make sure stitch regulator moves freely; that it
does not creep when sewing or that it sticks or
3. Wipe off all traces of the tacky anti-rust oil used binds.
to protect the polished and plated surfaces.
Give particular attention to the needle thread 12. Test wind a bobbin to be sure that bobbin winds
tension assembly. evenly.

4. Apply motor and light to machine and check 13. Check bobbin case tension with silk as described
operating behavior. on page 21.

5. Remove bobbin case and wash in Varsol, mak- 14. Polish the head to a satin finish. Do not leave
ing sure all traces of tacky oil have been an oily or a greasy film on any portion of
washed out from under the tension spring. the head or the cabinet.

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ORDER OF INSPECTION OF CUSTOMER'S
) MACHINES AT THE BENCH

1. Obtain complete information concerning the 7. Check relationship of needle with sewing hook.
customer's sewing problem before making any See pages 9 and 41 to 44.
adjustments.

8. Check pendulum motion of needle bar. See
2. Obtain samples of the customer's material and
pages 52 to 55.
thread for final testing.

3. Check threading of machine. 9. Inspect hook timing at central position of needle.
See page 43.

4. Inspect needle for-

10. Check needle bar height at extreme left needle a. Make. All SINGER needles are marked with
position. See page 44. the Company's trademark SIMANCO *

b. Comparison of size with the thread used.
11. Check feed mechanism for-
See page 10.

a. Timing of feed movement. See page 29.
c. Damage (Needle bent or blunt-needle eye
rough.) b. Feed dog height. See page 30.

d. Relation to needle hole in throat plate. Check c. Position of feed dog in throat plate slots.
for straight sewing and for maximum zigzag See page 32.
stitching. See pages 22 and 52.
d. Test feed for slight forward motion at "O',

5. Check condition of needle hole (or slot) in
presser foot and in throat plate. 12. Test bight controls, using needle perforation
tests. See pages 58 and 59.

6. Check thread clearance between position finger
and bobbin case holder. See page 42 13. Check arm shaft connection belt for looseness.

5

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SUGGESTIONS TO THE SERVICEMAN IN THE NOME

Quite frequently, when a machine is not sewing c. location in:
satisfactorily, the required adjustments can be accom- throat plate
plished in the home by a SINGER Serviceman. presser foot

relation to sewing hook point

Conditions such as faulty operation of the bight
d. damage from striking hook point
control or worn or damaged parts may have to be

remedied at the SINGER Shop, but this decision should 4. Check threading of machine, both upper and
be made only after the machine is thoroughly checked under threads.
in the exact order outlined below.

5. Check tensions of both threads. See pages 15
to 21. Use a Checklist similar to one shown on page 7
as a record for the man at the bench.
6. Inspect wound bobbins for proper winding.
See page 79. Bobbin must turn freely inside
bobbin case.
ORDER OF INSPECTION IN THE HOME

7. Inspect thread take-up springsettings.See 1. Inspect recent samples of sewing made by the
pages 19 and 20. customer on the machine, before checking ma-
chine itself. Ask customer to indicate on sewing
8. Check hook and needle relationship. See pages
samples the particular stitching faults she has 9,41, 43 and 44.
made reference to.

9. Check timing of needle bar and sewing hook
2. Check the combination of needle and thread during straight stitching. See page 43.
used by customer. See page 10.
10. Check position finger in bobbin case base for
proper thread space. See page 42.
3. Check needle for-

11. Check height of feed dog; its position in throat
a. wear or damage (needle blunt, bent or
plate.
burred).

o. position in needle clamp. See pages 12 and 12. Check performance of bight control mechanism.
88.. See pages 62 to 67 and 92 to 99.

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SAMPLE CHECK LIST
)                      FOR SERVICEMAN IN THE HOME
         ITEMS REQUIRING ATTENTION ARE INDICATED BY CHECK & MARK:

        1. QUALITY OF STRAIGHT STITCHING -CENTRAL           RIGHT.           LEFT

        2. ZIGZAGS IN STRAIGHT SEWING POSITION [ STAGGERS O

         3. FRAYS AND BREAKS SILK THREAD DURING -CHAINING                 #25 STITCH.
         FRAYS AND BREAKS MERC. COTTON THREAD DURING- CHAINING -          #25 STITCH.
       FREE-HAND EMBROIDERY D ZIGZAG SEWING [ STRAIGHT SEWING O

        4. QUALITY OF SATIN STITCH

        5. QUALITY OF ZIGZAG STITCHING_

         6. QUALITY OF TWIN NEEDLE SEWING.

        7. STALLS ON SATIN STITCHING O SEWS IN REVERSE AT "O" D

       8. MACHINE HARD TO START O KNOCKS AT HIGH SPEED D

       9. NEEDLE RUBS THROAT PLATE LEFT SIDE.        RIGHT SIDE

        ) 10. RELATION OF HOOK TO NEEDLE-TOO FAR AWAY [7 STRIKING NEEDLE

      11. HOOK TIMING-SLOW O FAST [J

      12. SKIPS ON STRAIGHT STITCHING O ON ZIGZAG O

     13. MACHINE LOOPS [ GATHERS

      14. HOOK RATTLES O]      FEED NOISY                   TAKE-UP LEVER
                                    IN LOW POSITION O         LOOSELY FITTED •

     15. BIGHT CONTROLS--EASY [7 HARD O TO MOVE

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NEEDLES AND THREADS



    For perfect stitching, the selection of the Class,     constant, maintaining an identical relationship be-
  Variety and Size of a needle to be used must be based    tween short-groove side of all 206 × 13 and 306 × 1
  upon the design and capacity of the particular sew-     needles and the hook point. Therefore, any increase
  ing machine as well as the work to be accomplished.     in the diameter of the blade results in a shifting of
                                                      only the centerline of the needle blade away from
                                                       the hook point.

                                      The distance Y, Fig. 2 from the butt-end
  For efficient and attractive sewing results, the    of the shank of the needle to the top of the
  needle blade is designed to be as slender as possible,                                                   needle eye is constant, regardless of needle sizes,



                             FLAT SIDE                      BLADE
                         OF SHANK





                                                   Fig 2. Needle Distances



 while sufficiently strong to avoid breakage at the                                                          within all Classes and Varieties of needles recom-
 needle eye. Therefore, the size of the needle eye, re-                                          mended for a particular sewing machine. This is to
 quired by the thread, determines the ideal size of the                                                      maintain the correct relationship of the height of the
needle blade. The actual size number of the                                                 needle eye to the point of the hook, throughout all
 needle is based upon the diameter of the                                                         possible changes of needles, as listed for the sewing
 needle blade at the eye of the needle. This    machine.
 diameter is constant for all sewing machine
needles of the same size number.                   However, the size of the needle eye increases with
                                                          the size of the needle to accommodate heavier thread.
  The distance X between the short-groove side     Therefore, any increase in the length of a needle
 of the needle blade and the position of the flat-side      for one particular machine is made from the top of
of the needle shank, seated in the needle bar, is                                                    the needle eye toward the point of the needle.





                              8

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HOOK AND NEEDLE RELATIONSHIP





                                                     Fig. 3.

                                         Relationship of Hook Point to Needle Eye



    The hook point should pass the needle as close as possible, without striking it. This will insure
hook point entry of thread loop during ornamental zigzag stitching. Adjust by loosening screw M4 and proceed
as instructed on page 41.

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CHART SHOWING RELATIONSHIP OF TYPES OF FABRICS,

                     THREAD AND NEEDLE SIZES AND

                      MACHINE STITCHES TO THE INCH



                                                              MACHINE STITCHES
                                                        PERINCH
                              THREAD        NEEDLE       INSIDE       TOP
     TYPES OF FABRIGS           SIZES           SIZES       SEAMS       STITCHING

Filmy material comparable to Net,   Mercerized 00
  Marquisette, Chiffon, Silk and Chif    100 Cotton                                9        15 to 20      15 to 20  fon Velvets, Voiles, Ninon         00 and 000 Silk
                                      Nylon Thread
 Sheer materials comparable to
                                         Mercerized O Lawn, Dimity, Synthetic Sheers,
                               80 to 100 Cotton
 Paper Taffetas, Pure Silks, Gossa-                                12 to 15       15 to 20                                        0 Silk
 mer Silks, Silk or Synthetic Tricots,
                                      Nylon Thread Synthetic Velvets, Satins

 Lightweight materials comparable
   Gingham, Chambray, Pique,    Mercerized 50
 Poplin, Percale, Cretonne, Chintz,   60 to 80 Cotton
 Faille, Bengaline, Wool Flannel,     A Silk          14                          15 to 18
 Wool Jersey, Wool Crepe, Cotton   Nylon or Dacron
 Velvets and Velveteens, Lightweight      Thread
 Suitings

 Medium heavy materials compar-
able to Corduroy, Crash, Gabar- Heavy Duty Merc. 40                                   16       10        12 dine, Rep, Heavy Suitings and Coat-40 to 60 Cotton
ings
Heavy materials comparable to
                              30 to 40 Cotton Sailcloth, Denim, Ticking, Over-                                                                10                                   18      8                              Dacron Thread coatings

  Plastic materials                  Mercerized 50
                                                            10




                            TWIST OF THREAD

   For ordinary stitching, either right or left twist
 thread can be used in the needle and in the bobbin.               HOLD THIS END
                                                                                         ROLL OVER


   To determine twist of thread, hold thread as shown
 at right and turn thread over toward you between
 thumb and forefinger of right hand. If thread is left
 twist, the strands will wind tighter; if right twist, the
 strands will unwind.                                                        Fig. 4. Determining the Twist of Thread



                           10

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TO ORDER NEEDLES FOR SWING-NEEDLE MACHINES


        Single needles for these Machines are of Class
                                                        thread will interfere with the successful use of the
                                                  machine.
and Variety14, 16 and20618.x 13 and are made in Sizes 9, 11,
                                                 Whenever a machine breaks thread or skips, try
                                                            the next size larger needle.
       The size of the needle to be used depends upon the
      size of the thread which must pass freely through the      Orders for needles must specify the Quantity re-
     eye of the needle.                                                              quired, the Size number, also the Class and Variety
                                                    numbers, separated by an x.

      Do not use rough or uneven thread or thread which
                                                   The following is an example of an intelligible order:
     passes with difficulty through the needle eye, as such
                                                             "100 No. 18, 206 x 13 Needles.



                     DESCRIPTION OF 306 x 1 TWIN NEEDLES

     Twin-needles of Class and Variety 306 × 1,
                                                                     "100 No. 14, 306 × 1-3 Needles."
    moulded together in one assembly, are made in Sizes
    11 and 14 for a maximum bight of 3mm. Always
     include desired bight when ordering, as shown by
                                              The best stitching results will be obtained with
    the following example:
)                                                   needles sold by Singer Sewing Machine Company.

                    15 x 1 NEEDLES FOR MACHINES OF CLASS 401


     These machines use needles of Class and Variety
                                                           15 x 1, available in sizes 9, 11, 14, 16 and 18.



                     TO PREVENT BREAKING OF NEEDLES

     The most common cause of needle breakage is the
                                                   unless the correct relative position between the
    pulling of the material by the operator, while the ma-
                                                        needle, throat plate and presser foot is maintained,
   chine is sewing.. This practice is entirely unnecessary,                                                  as instructed on page 52.
   as the machine (when properly adjusted) will feed the
    material correctly without assistance                   The needle or the hook point may break unless the
                                                   machine is correctly timed, as instructed on pages 41
     Attempting to perform zigzag stitching, while the   and 43.
  machine is fitted with straight stitching throat plate
  or presser foot, will also cause breaking of needles.   NOTE: Do not exceed number three on bight
                                                control when sewing with twin
    The needle may break unless it is correctly located
                                                         needles, otherwise bending or break-
   yin the needle clamp, as instructed on page 12, or                                              age will occur.


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LOGATION OF NEEDLE IN NEEDLE CLAMP

If the needle is incorrectly placed in the needle Fig. 6, facing the rear of machine, away from the
clamp and is incorrectly threaded, the machine will operator, then securely tighten needle clamp thumb
nor saw screw.

MOVE TO
NEEDLE CLAMP
HIGHEST
THUMB SCREW
POINT

FLAT SIDE
TO REAR
INSERT NEEDLE
UP AS FAR AS
POSSIBLE
LONG GROOVE
TO FRONT ->
SHORT
GROOVE

Fig. 5. Setting the Needle Fig. 6. Flat Side of Needle (Enlarged)

Make sure that needle is not blunt or bent. You will note from Fig. 6 thot the side of the
needle with the flat on the shank has a short groove

at the eye, while the opposite side, shown in Fig. 5,
has a long groove. On all machines the needle is
Loosen needle clamp thumb screw and insert needle threaded from the long groove side toward the short
in the needle clamp slot, all the way up against the groove; thus the needle on this machine is threaded
stop, with the flat side of the shank of the needle, see from front to rear.

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FORMATION OF THE LOCK STITCH (Continued)





                -THREAD TAKE-UP
                                                   THREAD TAKE-UP
                      LEVER                                                                    LEVER




                    WAN SIT





                    TENSION                                                         TENSION
                     DISCS                                                      DISCS




              NEEDLE                                                             • NEEDLE

             PRESSER FOOT                       PRESSER FOOT


    BOBBIN     HOOK POINT                                       HOOK-     BOBBIN CASE
    CASE
                                                 POINT
                 ROTATING HOOK                                                                                                          - ROTATING HOOK



     Fig. 9. Bobbin Thread Enclosed by Needle Thread                              Fig. 10. Stitch Completed


   Fig. 9 shows the third stage. The loop of the        Fig. 10 shows the final stage of locking the stitch.
needle thread has been cast off the hook and the    As the take-up lever rises to its highest position, the
take-up lever is rising quickly to take up all the slack   feed dog is completing its forward motion, thus lock-
thread.                                                    ing the two threads into a lock stitch.

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THE PERFECT LOCK STITCH

Fig. 11. Cross Section View
of Perfect lock Stitch Fig. 13. Cross Section View of Lock Stitch
with Loose Needle Thread Tension

When the tensions of both the needle thread and
Irregular stitching, such as is shown in
the bobbin thread are correctly adjusted, the stitches
Fig. 14, is usually caused by a combination of
will be locked in the center of the thickness of the
two or more of the following conditions:
material, as shown in Fig. 11.

When the tension of the needle thread is set too
a. Too loose or too tight needle thread tension.
tight in relation to the bobbin thread, excess bob-
b. Too loose or too tight bobbin thread tension.

Fig. 12. Cross Section View of Lock Stitch with
Tight Needle Thread Tension Fig. 14. Cross Section View of an
Irregular Lock Stitch

bin thread is drawn to the top of the material, causing
c. Damaged or improperly set tension spring on
a loose stitch, as shown in Fig. 12. bobbin case.
When the tension of the needle thread is set too d. Worn or damaged position finger.
loose in relation to the bobbin thread, excess Bent needle or damaged needle eye.
needle thread is drawn to the bottom of the material Improper feeding of material.
and the bobbin thread may lie straight along the un-
g. Use of wrong needle and thread combination.
derside of the material, as shown in Fig. 13.
h. Incorrect feed time.

15

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TENSION CONDITIONS

When checking and adjusting machine for tension proper tension of machine is to start with longest
conditions in relation to perfect sewing, use a Size 14 stitch and make sure that no looping appears in the
needle and "A" silk thread. Silk thread should be used stitching. Then shorten stitch to approximately #25
to establish proper "O' setting of needle thread ten. and note whether or not tension is satisfactory. If
sion and bobbin thread tension should be adjusted noticeable variations occur, make sure all traces of
with silk as described on page 21. After completing the tacky anti-rust oil are removed from the polished
sewing tests with silk, repeat these tests with #50 surfaces of the sewing hook and tension parts. See
mercerized cotton thread. Silk thread will show up instructions on page 4. Failure to wash the hook
any tendency for the machine to skip, fray or break with Varsol and to oil it after cleaning, may result in
thread before such conditions would be noted with many forms of looping trouble.
mercerized thread.

Test the machine at the following settings: SATIN STITCHING

1. Straight sewing at left-, central and right- When satin stitching, feed and tension adjustments
hand position of needle and at both longest must be very carefully made to insure a uniform
and shortest stitch setting. quality of satin stitch. Cording of fabric can be ex-

pected if excessive needle thread tension is employed 2. Maximum zigzag stitching at extreme left-
or if "O" dial tension setting is too high.
and right-hand position of needle and at
both longest and shortest stitch settings.

OPEN ZIGZAG STITCHING
STRAIGHT STITCHING
On open zigzag stitching it is not always possible to
The amount of needle thread tension required to lock the stitch in the corners without cording the fab.
make a satisfactory straight stitch will vary with each ric unless 1 or 2 thicknesses of some crisp underlay,
machine. A closely fitted hook may require between such as organdy, are used. When underlay is used,
#5 and #7 on dial tension. A loosely fitted hook may additional needle thread tension may be required to
require between #4 and #6. The safest test to insure lock the stitch in the corners.

16

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SEWING DIFFICULTIES CAUSES REMEDIES

Needle too small for size Use correct needle. See page
of thread. 10.

Too little needle thread Increase upper tension. Check
tension. Faulty take-up stroke of spring--replace if neces.
spring action. sary. See pages 19 and 20.

Irregular setting of stitches with large beads Free hook of any threads, gum
showing on the underside of the fabric. Clogged or sticky sewing or other foreign matter. If neces-
hook. sary replace hook and bobbin
case holder.

Provide .020 inch thread space
between bobbin case holder and
Insufficient thread space.
position finger. See page 42.
Inspect finger for roughness.

Needle thread tension Reduce tension.
Fabric drawing on open zigzag stitch of too tight.
medium stitch length.
Pressure on take - Up Reduce pressure on take-up
spring. See page 20.
) spring is too great. Reduce tension so that material
is not drawn yet stitch lies flat. Fabric drawing on all short zigzag stitching Needle thread tension
Underside stitching will not lock from medium to maximum bight. too tight.
in corners but in between needle

perforations.

Tension must be lighter for Material drawing when sewing with Silk,
Upper tension too tight. synthetic threads than for cotton. Nylon or Dacron Threads.
Reduce tension.

Use a solid foot in place of a
Material may be flagging
Machine skipping at extreme left or right hinged foot. Replace needle.
with needle. Needle may
needle position when sewing with Silk or Check height of needle bar in
be bent or setting too Nylon threads. relation to hook. See pages 44
high.
and 45.

All adjustments on needle thread tension, see page bobbin thread tension is correctly set at the factory
18, should be made on the assumption that the and should not be unnecessarily disturbed.

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TO REGULATE THREAD TENSIONS

NEEDLE THREAD TENSION

This machine is equipped with a one-cycle dial ten-
sion which, when set correctly, offers a barely per-
ceptible tension at "O" to a maximum at the end of
one complete rurn or thumb nur

At "O" there should be a barely perceptible amount

of tension, as otherwise, difficulty may be experienced
when sewing with twin needles, satin stitching and
other forms of closed ornamental stitching. Fig. 15. "O" Setting

Pull thread through tension discs to test amount of no tension. Then advance one hole to right to give
of tension on thread at "O" position. At this point minimum tension at zero position.
there should be a slight pull on the thread to indicate
TO OBTAIN INGREASED TENSION RANGE
there is a minimum tension which gradually increases
with the turning of thumb nut A to the right, providing On some occasions a slight increase in maximum
a full range of tensions with one revolution of the range of needle thread tension may be required for
thumb nut. If the pull is too strong for a minimum special work.
tension, press in dial C to disengage pin B on nut The additional tension may be obtained by using
from dial, and reset pin in next hole to left of previous tension indicator No. 125415 and tension spring No.
setting. Repeat this adjustment until a point is reached 45869 if the machine is not equipped with these parts.

TO REMOVE AND DISASSEMBLE NEEDLE THREAD TENSION

Turn thumb nut A over to the left (counter-clock- remove it. Then remove tension parts from stud as
wise) until it stops. To separate pin B in thumb nut A shown in Fig. 16.
from dial C, press in dial, unscrew thumb nut and

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TO REASSEMBLE AND REPLACE NEEDLE THREAD TENSION

Place tension parts on the stud as illustrated: 3. Tension spring must be mounted so the half coil
at front is in the lower position. 1. Make sure tension discs are free of oil, grit or)
grease.

2. Indicator must show plus and minus signs at top 4. Finger of slotted washer must point upward to
for operator's convenience. act as a stop for dial.

060

Е24740

Fig. 16. Needle Thread Tension Assembly
)
TO ADJUST THE THREAD TAKE-UP SPRING

STROKE OF SPRING TO SET TAKE•UP SPRING STROKE

The take-up spring J, Fig. 17 should be at rest Loosen set screw L, Fig. 17.
against its stop as the point of the needle enters the Rotate tension stud Z clockwise with a screwdriver
fabric. (turning whole tension assembly) to complete its action
over.
Rotate tension stud Z counter-clockwise with a
When adjusting take-up spring, the stroke screwdriver (turning whole tension assembly) to com-
must be adjusted first, then followed by the plete its action earlier.
pressure of the spring. Securely tighten set screw L.

G8

Fig. 17. Setting Fig. 18. Removing
Stroke of spring Tension Assembly

19

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PRESSURE OF SPRING Insert assembly into machine with plus and minus

signs of indicator in uppermost position and hold ten-

sion assembly in place.
Tension on thread take-up spring should be just
sufficient to take up slack of needle thread until needle Move loop of spring to the left so that it may come
point reaches the fabric. to rest against its stop.

1.8

E25055 E25056

Fig. 19. Showing Fig. 20. Spring
Spring Left of Center Line

Excessive pressure will cause fabric to cord (draw) Securely tighten screw G8, Fig. 18.
during satin stitching or wide bight zigzag stitching.
Test pressure of spring to determine if a finer adjust-
ment is needed.
Insufficient pressure will cause looping or thread
breakage. NOTE: If more pressure is required, move small tail
of spring L8 into the next stud slot to the
right of previous setting.

If less pressure is required, move small tail of springTO ESTABLISH MINIMUM PRESSURE OF SPRING
L8 into the next stud slot to the left of previous setting.

Turn screw G8, Fig. 18 counter-clockwise and NOTE: A very fine adjustment for pressure of the
remove tension assembly. spring can be had by loosening screw G8,
Fig. 18 and turning complete assembly
clockwise to increase pressure and counter-
slide spring on tension assembly so that tail of
clockwise to decrease pressure.
spring L8, Fig. 19 is in one of the stud slots and top
of spring J, is just left of center line on indicator in Retighten screw G8 and test spring pressure
the area between dotted lines, illustrated in Fig. 20. by sewing.

20

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TO REGULATE BOBBIN THREAD TENSION

BOBBIN THREAD TENSION

The tension on bobbin thread is regulated by the)
larger screw nearest the center of tension spring, as
shown in Fig. 21.

When adjusting bobbin tension, a slight turn of the
screw is all that is needed to make a fine adiustment

because the full range of tension from zero to a maxi-

mum is made within 1-1/4 turns of tension regulating

MORE
TENSION

E23575

LESS Fig. 22.
TENSION
SUGGESTED METHOD E74.739
FOR SETTING BOBBIN THREAD TENSION
Fig. 21. Bobbin
Thread Tension Wind bobbin with a 50 yard spool of sixe "A"
silk thread.

Thread bobbin case and adjust tension so that
To increase tension, turn this screw gradually over
weight of bobbin case with a bobbin of 50 yards of
to the right.
"A" silk will cause case to slide slowly, when held sus-

pended by the thread. See Fig. 23. For correct ten-
To decrease tension, turn this screw gradually over sion, its downward movement should be very slow.
to the left.

TO REGULATE BOBBIN THREAD TENSION WITHOUT

REMOVING BOBBIN CASE

The thread tension screw is conveniently adjusted
while bobbin case remains in machine.

To adjust, raise take-up lever almost to its highest
point, tilt machine back on its hinges and turn the
large screw on the bobbin case as shown in Fig. 22.

Turn screw over away from operator to loosen ten.

@ sion or over toward operator to tighten tension. Fig. 23. Checking Bobbin Thread
21 Tansion

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