Singer CLASS 20 User manual

20533
ADJUSTERS
MANUAL
SINGER
SEWING MACHINES
CLASS 20
SINGLE THREAD CHAIN STITCH
THE SINGER MANUFACTURING COMPANY
Copyright, U. S. A., 1936, 1952 and 1954, by The Singer Manufacturing Company
All Rights Reserved for all Countries
*A Trade Mark of THE SINGER MANUFACTURING COMPANY

rom-mo n» p
ry
£22788
I
Fig. 2. Principal Parts of Machine 20-10
Thread Hole in Tension J. Clamp Screw
Bracket K. Stitch Regulator
Tension Discs L. Looper
Tension Regulating M. Cloth Plate
Thumb Nut N. Presser Foot
Thread Nipper ©. Cloth Guide Thumb Screw
Spool Pin 45P. Cloth Guide
Thread Pull Off Q. Needle Set Screw
Hand Wheel R. Presser Bar Lifter
Driving Handle S. Presser Bar
T. Needle Bar
Clamp

3
DESCRIPTION
Machines of Class 20 are practical, convenient, single thread
chain stitch sewing machines made especially for children. They may
also be used by adults for repairing clothes and light household
articles.
Machines 20-1 and 20-10 are operated manually. Machine 20-2
is operated by motor, although it too can be operated manually by
removing motor and attaching a handle to hand wheel.
All Machines of Class 20 have a cloth guide for use when sewing
close to edge of material.
The rotary looper makes one revolution per stitch.
The needle is threaded from left to right.
.. An arm side cover encloses movable parts of arm of Machine
20-10. ^ o4 i
A clamp, for fastening machine to a table or desk, is furnished
_ with all Machines of Class 20.
All electrical parts of motor of Machine 20-2 are enclosed in a
bakelite shell, eliminating the danger of electrical shock.
The motor requires no attention except occasional oiling. It must
be used only on 110 volt, 60 cycle, alternating current (A. C.).
TO PREPARE MACHINE FOR SEWING
1. Inspect for possible damage incurred during transit. Bent shaft,
broken wheel, etc.
Check machine for free turning qualities.
Rinse with Varsol, then wipe off all traces of tacky, anti-rust oil
used to protect polished and plated surfaces.
Oil machine completely. See page 14. Wipe away any surplus cil.
5. Check condition of needle before making sewing tests. See item
` 4, top of page 15.
6. Check timing of feed and position of looper in relation to needle.
See page 9.
7. Check looper shaft for correct amount of end play. See page 9.
Check hand wheel for correct amount of end play. See page 13.
Glazed cotton thread is recommended for improved sewing results.
10. Sew-in machine and check stitching. See page 8.

DESCRIPTION OF 24X 1 NEEDLES
Needles for Machines of Class 20 are of Class and Variety 24 x 1
in Sizes 9, 11, 14 and 16.
The size of needle to be used depends upon the size of the thread
which must pass freely through eye of needle.
— iae
Do not use rough or uneven thread or thread which passes with
difficulty through needle eye, as such thread will interfere with the
successful use of the machine.
Although needles are made with different diameter of blades,
certain dimensions remain constant for all needles of the same Class
and Variety.
FLAT
SIDE
BLADE
. LL
OF
SHANK
i
-L——
j
|
£20961
E
E
NEEI
Fig.
3.
Needle
Distances
For example, the distance X between the short-grooved side of
needle blade and the position of the flat-side of the needle shank,
seated in needle bar, is constant, maintaining an identical relation-
ship between short-groove side of all 24 x 1 needles and looper point.
Therefore, any increase in diameter of blade results in a shifting of
only the centerline of needle blade away from looper point.
Another constant is distance Y from end of shank to top of eye,
maintaining an identical relationship between needle eye and looper
point, during formation of thread loop.
However, the size of needle eye increases with the size of needle
to accommodate heavier thread. Therefore, any increase in the length
of a 24 x 1 needle is made from the top of the needle eye toward the
point of the needle.

HOW TO CHECK A
= NEEDLE FOR STRAIGHTNESS
Plaċe flat side of needle on cloth
plate or any other flat solid surface
PER and hold up to light, as shown in
Fig. 3A. A straight needle will show
an even amount of light under it
and point will be in line with shank.
Fig. 3A. Checking Needle
TO SET NEEDLE IN NEEDLE BAR
Turn hand wheel over MOVE TO
away from operator until ONT
needle bar reaches its high-
est point. Loosen needle set
screw A, Fig. 4. With flat
side of needle to the right, INSERT
Baza ; NEEDLE UP
as shown in Fig. 4, insert AS FAR AS
needle up into needle bar POSSIBLE
as far as it will go and
tighten set screw A,
pe
Fig. 4. Setting the Needle

FORMATION OF SINGLE THREAD CHAIN STITCH
NEEDLE
OF
LOOPER LOOPER LOOPER LOOPER
Fig. 5. Looper Entering Fig. 6. Loop Being Carried
Loop of Needle Thread Through Previous Loop
Fig. 5 shows the first stage in stitch formation. The needle, after
descending to its lowest point, has been slightly raised and a loop
of thread is thus formed which is immediately entered by point of
looper and carried by it into the preceding loop.
Fig. 6 shows the second stage. The loop of thread is being car-
ried by point of looper down through preceding loop. The heel of
looper is about to release preceding loop.

FORMATION OF SINGLE THREAD CHAIN STITCH (Continued)
s LEED
ESE ea
LOOPER
Fig. 7. Loop Enlarged and Fig. 8. Loop Further Enlarged
Previous Loop Drawn Up and Previous Loop Completed
Fig. 7 shows the third stage. The loop is further enlarged by the
downward movement of point of looper. The preceding loop has been
released and is being drawn closer to fabric by movement of looper,
assisted by the raising of needle bar.
Fig. 8 shows the completed stitch. The loop of the stitch in process
is drawn down to its fullest extent by looper. The preceding stitch
has been drawn closely againstthe underside of fabric and is com-
pleted, the needle bar having reached its highest point.

TO REGULATE TENSION ON THREAD l d
Tension on thread, =
once regulated, seldom re-
quires changing.
The thread nipper
spring B, Fig. 9 is automat-
. Jcally controlled by needle
- bar lever at C, Fig. 9. The
nipper is opened just be-
fore needle bar reaches its
highest point and remains
open until needle bar has
drawn off sufficient thread
for next stitch.
The thread nipper
should open to approxi-
mately 1/32" when needle
bar is at its highest point. Fig. 9. To Regulate Tension
If puckering or thread breakage occurs at light tension settings,
raise needle bar to highest point and check nipper opening. If neces-
sary, reshape contact finger of nipper so that correct opening is
obtained.
If stitches are so tight that they pucker material, decrease tension
by turning thumb nut E, Fig. 9 over to the left (counter-clockwise). If
stitches are too loose, increase tension by turning thumb nut E over to
the right (clockwise).
Note:—lf thread bearing surfaces are rusted, they should be
replaced.
TO REGULATE LENGTH OF STITCH
The length of stitch is
regulated by lever F, Fig. 10.
For a longer stitch, move lever
F down away from operator.
For a shorter stitch, move lever
F up toward operator.
Fig. 10. To Regulate Length of Stitch

TO TIME FEED AND LOCATE FEED
ECCENTRIC AND LOOPER
NOTE: If screw L is loosened, all adjustments (timing feed and
locating feed eccentric and looper) must be made as instructed below.
Fig. 11. Timing the Feed
To time feed, turn hand wheel over away from operator until
looper point is centered with needle, as shown at M, Fig. 11. Loosen
set screw L, Fig. 11 and turn feed eccentric K so that screw L is in
position shown in Fig. 11.
To locate feed eccentric K, hold pinion gear Q, Fig. 17 against
machine and adjust feed eccentric K for a slight amount of clearance
(not to exceed .003 inch,) as shown in Fig. 11A. Do not tighten screw L
at this time.
To locate looper R, move looper as
close to needle as possible as shown at
D, Fig. 11A, and then, after all adjust-
ments have been made as instructed
above, tighten set screw L, Fig. 11. Re-
check adjustments.
Fig. 11A. Locating Feed
Eccentric and Looper
TUse .003 Feeler Gauge Serial 187928 Complete.

>
TO REMOVE AND REPLACE CLOTH PLATE
To remove cloth plate U, Fig. 12, first remove thumb screw T
and cloth guide Y. Raise presser bar and needle bar to highest points.
Remove screws Z. Lift cloth
plate slightly at U (to clear
feed dog) and slide it out
between presser foot and
feed dog.
mar
To replace, raise presser
bar and needle bar to high-
est points. Pass cloth plate
between presser foot and
feed dog, fit cloth plate
slots over feed dog teeth
and replace cloth plate
screws Z. Replace cloth
guide Y and thumb screw
T.
Fig. 12. Removing and
Replacing Cloth Plate
TO REMOVE AND REPLACE LOOPER
CAUTION: When removing looper, needle must be high enough
for looper to pass without striking needle.
To remove looper R, turn hand wheel over away from operator
until set screw L is in approximate position shown in Fig. 13. Loosen
screw L and remove looper R from end of looper shaft S.
Fig. 13. Removing Looper
To replace looper, turn hand wheel until needle bar is at its
highest point. Fit looper R (point down) into slot in looper shaft S.
Time feed and locate feed eccentric K and looper R, as instructed on
page 9.

11
TO REMOVE AND REPLACE FEED ECCENTRIC
To remove feed eccentric K, loosen screw L and remove looper
as instructed on page 10. Then slide feed eccentric K from looper
shaft S.
To replace feed eccentric, place raised portion, or "boss," (see
inset, Fig. 13,) against face of machine with slot of feed dog H, Fig. 13
riding on feed eccentric. Replace looper as instructed. Time feed and
locate feed eccentric and looper, as instructed on page 9.
TO REMOVE AND REPLACE FEED DOG
To remove feed dog H, Fig. 13, first remove looper and feed
- eccentric, Then remove screw G to allow feed dog and spring to be
. removed.
To replace, position feed dog and spring as shown in Fig. 13,
with end of spring in hole J. Replace and tighten feed dog screw
G, Fig. 13, making certain that feed dog can be moved back and forth
by hand. Replace feed eccentric and looper and adjust as instructed on
page 9.
TO REMOVE AND REPLACE NEEDLE BAR
To remove needle bar:
1. Remove needle and needle set screw.
2. Remove cloth plate.
3. Remove arm side cover by first removing screws on rear side of
machine which hold cover in place.
4. Turn hand wheel over until needle bar reaches its highest position.

12
Remove hinge screw E2, Fig. 14. Then disengage connecting stud
J2, Fig. 15 from “socket” L2 in needle bar lever.
Remove connecting stud J2 from needle bar. -
Remove needle bar from top of machine.
ESPSDR
Fig. 14. Removing Needle Bar
To replace needle bar:
1.
NDD
.
Insert needle bar so that it fits between sides of guide bracket
D2, Fig. 15.
Insert connecting stud J2, Fig. 15 in needle bar hole with round
head of stud on same side of needle bar as the number "6"
stamped near top of needle bar.
Fit round head of connecting stud J2 into “socket” L2 as shown in
Fig. 15.
Replace and secure hinge screw E2, Fig. 14.
Replace arm side cover and tighten screws.
Replace cloth plate.
Replace needle and needle set screw.

(
13
TO REMOVE AND REPLACE PRESSER BAR
E2280}
Fig. 15. Removing and
Replacing Presser Bar
To remove presser bar:
1. Raise needle bar to highest po-
sition. |
2. Remove cloth plate.
3. Remove looper and feed eccen-
tric.
4. Remove feed dog.
5. Remove arm side cover by first
removing screws on rear side
of machine which hold cover in
place.
6. Lower presser bar and remove
screw A2 and lifting lever B2,
Fig. 15. While holding spring
C2 and guide bracket D2 in
place, remove presser bar. Then
remove spring and guide
bracket.
To replace presser bar, fit
spring C2, Fig. 15 in position and
slide presser bar up through bottom
hole, spring, and top hole in ma-
chine arm. Compress spring from
bottom and insert guide bracket D2
under spring, with sides of bracket straddling presser bar and needle
bar. Place lifting lever in position and align holes of presser bar, guide
bracket and lifting lever. Replace and tighten screw A2.
Replace, in order, arm side cover, feed dog, feed eccentric,
looper and cloth plate.
TO ADJUST HAND WHEEL
FOR CORRECT AMOUNT
OF END PLAY
To adjust hand wheel for correct
amount of end play, loosen set screw
N, Fig. 16, hold hand wheel O against
machine and adjust stud P for a slight
amount of hand wheel end play’ (not
to exceed .003 inch), as shown in Fig.
16. Then tighten set screw N.
Fig. 16. Adjusting for End Play
of Hand Wheel...
TUse .003 Feeler Gauge Serial 187928 Complete.

14
TO REMOVE AND REPLACE HAND WHEEL
To remove hand wheel O, Fig. 17, loosen screw N and remove
wheel O and stud P as a unit. Slide stud P and wedge pin Fig. 17
from wheel and place wedge pin in a container to avoid loss.
ig. 17. Exploded View of Hand Wheel Assembly
To replace hand
wheel, place wedge pin
on “flat” nearest head
of stud P and insert
stud through hole in
hand wheel O. Hold
stud in hand wheel
and, with "flat" of stud
toward operator, insert
stud into hole in lower
arm of machine. Make
sure that teeth of pin-
ion gear Q, Fig. 17 and
teeth of hand wheel O
mesh. Adjust for end
play, as instructed on page 13, and tighten set screw N, Fig. 17.
TO OIL MACHINE
For best results, the machine should be oiled occasionally with
SINGER* SEWING MACHINE OIL.
Apply one drop of oil to each place where one part of machine
is in moving contact with another.
Every six months put one or two drops of oil into oil hole at each
end of motor of Machine 20-2.
SUGGESTIONS TO THE SERVICEMAN
Order of Inspection:
1. Obtain complete information concerñing customer's sewing prob-
lem. Ask for sample of material and thread.
2. Check threading of machine. See Fig. 1.

2» Dg Ow OO
oD eh >
1.
2.
15
Check relationship of needle with looper. See page 9.
Inspect needle for—
a. make. All SINGER needles are marked with Company's trade
mark "SIMANCO*",
b. wear or damage. (Needle bent, blunt—needle eye rough)
c. relationship to presser foot and cloth plate. See page 15, below.
Check slot in presser foot and hole in cloth plate for burrs, wear
or damage. 7 I
Be sure looper is not bent or blunt.
Check looper for needle point and scissor point burrs.
Check timing of feed. See page 9.
Be sure feed dog is not bent.
CAUSES OF NEEDLE BREAKAGE
Operator pulling material while machine is stitching.
Incorrect timing of feed, See page 9.
Incorrect location of needle in needle bar. See page 5.
Incorrect position of needle in relation to presser foot and cloth
plate. See page 15, below.
Incorrect location of looper. See page 9.
CAUSES OF THREAD BREAKAGE
Incorrect threading. See Fig. 1.
Tension too tight. See page 8.
Incorrect opening of thread nipper. See page 8.
Needle blunt or bent, needle eye sharp.
Burr on looper.
Roughened hole in cloth plate.
CAUSES OF THREAD LOOPING
Incorrect threading. (Thread may have slipped from between ten-
sion discs.)
Tension too light. See page 8.
RELATION OF NEEDLE TO PRESSER FOOT AND CLOTH PLATE
If needle strikes presser foot or cloth plate, check for the follow-
ing causes:
pi de p m M
Bent needle—(Replace)
Worn, damaged or bent needle bar—(Replace)
Bent presser bar or presser foot—(Replace)
Bent or loose guide bracket D2, Fig. 15—(Correct)
Cloth plate incorrectly seated—(Correct)

16
TO START AND STOP MOTOR OF MACHINE 20-2
CAUTION: Before
starting motor, be sure
current is 110 volt, 60
cycle, alternating cur-
rent (A. C.).
wen To start motor,
press down on switch
H2 and lever K2, Fig.
18 at the same time.
Release lever K2 and
rubber roller back of
hand wheel will touch
rim of wheel and drive Fig. 18. To Start
machine. | and Stop Motor
To stop motor, press down on switch H2, Fig. 18.
TO CHANGE SPEED OF MACHINE 20-2
Machine 20-2 has two sewing speeds; a slower speed for careful
stitching, or for young children, and a faster speed for ordinary
straight sewing.
To change speed,
place machine in posi-
tion shown in Fig. 19.
Remove motor pulley
guard X by pressing it
down and sliding it
toward you,
For slow speed,
move belt to outside
grooves V in pulleys.
For faster speed, move
belt to inside grooves
W.
Replace guard X
with slots over metal
tabs in base of ma-
chine and press guard
down and away from
you into place.
Fig. 19. Changing Speed of Machine 20-2

SINGER Needles should be used
in SINGER Machines
These Needles and their Containers
are marked with the
Company's Trade Mark “SIMANCO.*” ,
Needles in Containers marked
"FOR SINGER MACHINES"
are NOT SINGER made needles. 2