Pfaff 3334 User manual

IS'
' " (D
(TOFF) 3334
Automatic Lockstitch Bortocker
SERVICE MANUAL
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Foreword
Pfaff sewing machines are quality products. Constant checks ore
being made throughout the production process to ensure that o
high quality standard is maintained.
But even the best sewing
machine has to be operated and serviced skillfuify if satisfactory
results are to be obtained.
This book has been compiled cs a source of information for all
Pfaff mechanics servicing Pfaff 3334 automatic bartackers and
will serve as a valuable guide in performing minor repairs and
adjustments.
We have made every effort to render the presentation of these
instructions as simple as possible and have included numerous
illustrations inorder to afford a betterunderstanding.
G. M. PFAFF AG
Kaiserslautern Branch
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SERVICE MANUAL
PFAFF 3334
Automatic Lockstitch Bortocker
From the library of: Superior Sewing Machine & Supply LLC

Contents
Page
A. Description and Operation 5
1. General Information 5
a. Purpose of Employment 6
b. Application Possibilities 7
2.
Operation 8
a. Efficiency Rating 8
b.
Mode of Operation 8
c. Sewing Cycle 9
3. Mechanical Setup . 13
a. Shuttle ond Needle Bar Drive . 13
b. Feed Motion 13
c. Automatic Stop Motion 18
d. Thread Trimming Action 20
B. Instructions for Repair 30
1. Disassembly , 30
2. Assembly 31
3. Adjustment and Check-Up 33
a. Timing the Shuttle and Setting the Needle Bar ot Correct Height 33
b. Timing the Feed Motion 39
c. Timing the Thread Trimming Action 46
d. Adjusting the
Work Clamp 49
e. Timing the Stop Motion 49
f. Timing the Thread
Nipper and Adjusting the Thread Tension 53
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4. Stitching-Off 60
a. Sewing Thread 60
b. Needle 60
c. Bobbin Winding 61
d.
Needle Threading 62
e. Threading the Bobbin
Case 63
f. Inserting the Bobbin
Case 63
5. Setting-Up 64
a. Individual Power Drive . 64
b. Bench Power Drive 67
c. Individually Powered Machine on Power Benching .... 68
6. Subclass Conversion 69
a. Changing the Feed Cam 69
b. Changing the Knife Cam 70
c. Changing the Work Clamp Feet 71
d. Changing the Feed Plate 71
7. Trouble Shooting 71
a. Skipped Stitches 71
b. Thread Breaking 71
c. Needle Breaking 71
d. Heavy Working 72
e. Irregular Stopping 72
8. Machine Care 75
a. Cleaning and Oiling 75
b. Dismantling the Shuttle Race 77
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C. Electromagnetic Control 78
1. General Information 78
a. Brief Description 78
b. Key to Symbols Used 79
2.
Operating Instructions for X35 and X45 Devices 80
a. Turning on Master Switch HS 80
b. Inserting the
Work and Operating
Foot Switch FS (1st Switch Position) 80
c. Starting the Machine by Operating
Foot Switch FS (2nd Switch Position) 80
d. Sewing Cycle
and Automatic Stopping of Machine .... 80
3. Working of Device 84
a. Master Switch HS 84
b. Foot Switch FS 84
c. Solenoid EM 84
d. Solenoid HM and Switch ES 86
e. Switch SS 86
4. Mounting and Adjustment Procedures 87
a. Switch ES 87
b. Lever B 87
c. Solenoid EM 87
d. Switch SS 87
e. Solenoid HM 87
D. Subclass Information 91
1. Subclasses Having the Same Gear Ratio 92
2. Subclasses Having the Same Knife Cam 93
3. Subclosses Requiring Additional Parts 94
4. Principal Parts Varying from
One Subclass to Another .... 95
5. Special
Organizational Parts 96
6.
lock Designs Arranged by Shapes 99
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A. Description and Operation
Stitch Type:
LoopTaker System;
Bobbin Capacity:
Needle System:
Foot Lift:
Maximum
Length of Tack:
Maximum
Width of Tack:
Classes of Work:
1. General Information
Lock stitch
Oscillating (central bobbin) shuttle
66 yds No. 40/3 cotton
Model A and B machines use System 34 R needles for
ordinary sewing operations, and System 34
Lr or 34 D
needles for leather work (needle size up to
110). Model C
machines use System 332 R needles for ordinary sewing
operations, and System 332 Lr or 332 D needles for
leather work.
(Additional needle systems thot may be used are listed
on page 60).
'V32" to Vb", or 15 to 16 mm (on earlier machines the
foot lift ranges from "/as" to 'V32", or 9 to 10 mm).
1Vib", or 36 mm
Va",
or 22 mm
ModelsA and Bare used for light- to medium-weight
materials.
Model C is used for heavyweight materials (machine
features higher needle bar rise and larger take-up
motion).
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a. Purpose of Employment
The Pfaff 3334 is specially designed for automatic bartacking and short
seaming operations of every description. While both the shape of the tack
and the number of stitches per tock ore predetermined for each subcloss, the
size of most tacks can be varied within certain limits.
The machine'sfield of application embraces oil branches of the sewing indus
try. Thus, opart from bartacking, it may be employed for stitching staying
seams, attaching belts and straps, and stitching arnamentol tacks, to name
justa few additional applications. (See ill.on page 7).
The Pfaff 3334 is of the cylinder-bed construction. Its slender cylinder arm
greatly facilitates the handling of the work, particularly when tubular arti
cles are being stitched.
If desired, the Pfaff 3334 automatic bartacker can be fitted with electro
magnetic control, this version being known as Pfaff 3334 X 35 in Models Aand B,
or Pfaff 3334X45 in Model C. On this machine, the functions of raising the
work clomp and storting the machine are performed by solenoids, and the two
treadles of the standard model ore replaced by a foot switch (Fig.4).
Feed Motion
The work is held between, and guided by, the work clamp and the feed
plate. To produce the desired tack, the material is moved up and across the
machine bed while the needle moves up and down. The feed motion is deriv
ed from the feed com.
The Pfaff 3334 attains a speed of up to 1,200 s.p.m., depending on the
thickness of the material as well os the size and shape of the tack. To convert
the machine from one subclass to another, it will be sufficient normally to
exchange the feed plate and the clamp feet rather than the complete work
clamp.
If, however, the shape and size of the tack or the number of stitches in the
design ore to be changed, the feed cam, knife cam, worm and worm wheel
have to be exchanged.
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b. Application Possibilities
Fig. 1
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2. Operation
a. Efficiency Rating
The output of on automatic bartacker is determined by the following factors:
(1) the number of stitches per tack,
(2) the handling times involved in a given operation (which, in turn, are de
termined by the size and bulkineess of the workpiece),
(3) the quality of material and thread,
(4} the handy arrangement of the work, and
(5) the speed of the machine.
The Pfaff 3334 automatic bartacker can be fitted to moke 7, 9, 14, 16, 18,
21, 24, 28, 32, 36, 42, 48, 56, and 72 stitches per tack. The tack design diagrams
contained in the Subclass Catalogue (Form No. 10080) illustrate the versati
lity of this efficient machine. In special coses, it may be advisable to sub
mita sample of the moterial to be sewn as well as a specimen of the finished
work either to the Kaiserslautern Branch of G.M. Pfaff AG or the nearest
Pfaff industrial sewing machine representative.
b. Mode of Operation
While both the length and width of a bartack con be varied within certain
limits by simply adjusting a lever, its shape as well as the number of stitch
es it comprises can be varied only by exchanging the feed cam. In many
instances, the worm gear assembly and the knife cam must be exchanged
in addition.
The entire sewing action, including the stopping of the machine, is controlled
automatically.
The machine is equipped with two cams which ore corried on a joint trans
verse shaft on either side of the machine arm.
The right, or feed, cam has two pattern-forming grooves, one on each side.
While the groove on its outside face controls the crosswise feed
motion,
the lengthwise feed motion emanates from the groove on its inside face.
The feed cam, in addition, carries one or several stop tripping segments as
well as one or several thread nipper tripping segments. Whereas the former
serve to stop the machine at the completion of a sewing cycle, the latter
actuate the thread nipper.
The number of stop tripping segments and thread nipper tripping segments
provided on the rim of the feed cam depends on the number of tacks pro
duced per cam revolution.
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The left,or knife, cam operates the needle and bobbin thread knives.
As the knives swing forward from the inoperative to the stand-by position,
asufficient amount of thread is pulled from the spool and the bobbin with
which to start the next tack.
As the machine makes the last stitch of the tack, the groove in the knife cam
couses the lower, or main, tension to be released so that the last stitch knot
is pulled ino the material.
The main tension will not by reactivated until the machine, depending on the
subclass, has completed three to four stitches after starting a new tack. In
this way, puckering of the fabric is successfully eliminated. This is particularly
important for stitching
delicate fabrics or sewing with long stitches.
The machine is
started by depressing the right treadle. This action causes
the stop motion lever to swing back
and the tripping and locking levers to be
interlocked.
The locking lever prevents the operator from inadvertently raising the work
clamp while the machine is in operation since this action would cause the
knives to trim the threads.
By the same token, the machine cannot be started while the work clamp is
roised.
When the machine is started, the driving belt is shifted from the idler to the
driving pulley and, conversely, when the machine stops, it is returned from
the driving to the idler pulley.
All the operator has to do to start the sewing cycle is to press down the right
treadle. After the machine has stopped automatically, she raises the work
clomp by depressing the left treadle.
c. Sewing Cycle
The work is held between the work clamp and the feed plate and is advanc
ed after each stitch to form the predetermined tack design. This design is
produced by moving the material up and across the machine bed as the
needle moves up and down. Fig. 3 illustrates the sewing cycle of a rectang
ular tock.
When the machine has been started by depressing the right treadle, the
needle enters the fobric for the first stitch. After the first stitch has been
completed and the needle has risen clear of the fabric again, the work is
moved across the machine bed the predetermined distance between stitches.
This cycle is repeated until the tack is completed.
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1 == Needle bar frame
2 = Needle bar
3 = Work clamp
4 = Clamp foot lifting lever
5 = Thread wiper wire
6 = Feed plote
7 = Work clomp feet
8 = Presser bar
9 — Presser bar lifting bracket
Fig. 2 Feed plate and work clamp
While the last stitch is being formed, the stop motion is released so that
the
machine stops exactly in the predetermined position after completing
the last stitch.
When the left treadle is depressed, the needle and bobbin threads are trim
med and the work clomp raised for easy removal of the work.
Electromagnetic Control
On machines fitted with electromagnetic control, various operations that
used to be performed by hand or foot previously, such as raising the work
clomp and starting the machine, are controlled by solenoids. On the Pfoff
3334, the solenoids ore activated by depressing push-button switch FS (Fig. 4)
on the foot rest.
When this button is pressed down to the first switch position, the work clamp
is lowered onto the goods. At this stage, the work clamp may be raised or
lowered indefinitely by depressing or releasing the push button, as may be
required to odjust the position of the work under the clamp. Depressing the
button to the first switchposition will not start the machine.
Only when the button is depressed to the second switch position will the
machine be storted by a second solenoid (Fig. 4).
10
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Crosswise motion
begins
Lengthwise motion
begins
Crosswise motion
begins
Lengthwise motion
begins
Crosswise motion
begins
Schematic Seam Construction Diagram
13 U
11<^^2r-2-^7
10 9 8
Crosswise motion
completed
Work piece
Work clomp
Feed plate
Lengthwise motion
completed
Crosswise motion
completed
Lengthwise motion
completed
Crosswise motion
completed
1
—1—1
lall
g
iiaHiiiH;HiK|^88|i88s
Fig.3 The individual phases of sewing a four-sided tack
11
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Fig. 4 Pfaff 3334 X35or X 45 fitted with electromagnetic control
12
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3. Mechanical Setup
From the foregoing description of the sewing action of a bortocker it is evident
that this machine must incorporate the following essential mechanisms, in
addition to the shuttle and needle bar drive mechanisms found in any ordinary
sewing machine:
(1) a special feed mechanism which advances the workpiece in the prede
termined direction offer each stitch,
(2) an automatic stop control which stops the machine as soon as the predeter
mined number of stitches have been mode and the take-up lever has
almost reached the highest point of its stroke, and
(3) a trimming mechanismwhichsevers the needle and bobbin threads.
a. Shuttle and Needle Bar Drive
The shuttle driving motion is derived from the cranked arm shaft and trans
mitted to the shuttle via a connecting rod, an oscillating rock shaft, a crank
with slide block, end the shuttle driver shaft. This mechanical setup produces
the oscillating motion required for this type of shuttle.
The needle bar is moved up and down by means of the needle bar crank and
the needle bar connecting link.
b. Feed Motion
The feed motion lengthwise and across the machine bed is controlled by
two pattern-forming grooves, one on either face of the feed cam.
Whenever the material is to be moved in a stroight line lengthwise or across
the machine bed, this motion is controlled by only one of these grooves.
The feed motions emanating from both grooves are combined to produce
circular, triangular or other tacks whose sides extend at on angle to the true
lengthwise or crosswise direction of feed.
The groove on the outside face of the feed cam controls the feed motion
crosswise of the machine bed. As the feed cam revolves, o roller located at
the top end of the feed across regulator (Figs. 6 & 7} rides in this groove
and transforms the throws emanating from its curvature into a reciprocating
motion which is transmitted to both the feed plate carrier bar and the work
clomp by means of a ball joint connection. The amount of motion across
the machine bed can be adjusted by changing the position of the ball joint
connection in the slot of the feed across regulotor.
13
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1 = Idler pulley
2 = Driving pulley
3 = Hinge pin
4 =
Hinge screw
5 = Oscillating
rock shaft
6 = Shuttle driver
shaft crank
7 = Slide block
8 = Shuttle driver
shoft
9 = Shuttle driver
10 = Shuttle race
11 = Shuttle
12 = Bobbin case
13 = Take-up crank
14 = Arm shaft
15 = Shuttle drive
connecting
rod
16 = Needle bar
17 = Needle bar
connecting
stud
18 = Needle bar
connecting
link
19 = Hinge pin
20 = Take-up lever
link
21 = Take-up lever
22 = Needle bar
crank
'-^1 nsi
1 4 1
—
\ 1
1
1
6 ;
Fig. 5 Shuttle and needle bar drive
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1 = Arm shaft
2 = Feed cam
driving worm
3 = Idler pulley
4 = Driving pulley
5 = Feed com
6 — Worm wheel
7 = Bearing
bracket
8 = Guide plate
9 = Slide block
10 = Hinge screw
11 = Feed across
shaft
12 = Feed across
shaft crank,
front
13 = Hinge stud
14 = Guide plate
15 = Feed across
driving block
16 = Feed
plate
17 = Feed plote
carrier bar
18 = Ball joint
connection
19 = Feed across
regulator
\
V\\ 1
\V
Fig. 6 Feed across motion (longitudinal section)
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] = Roller
2 = Roller stud
3 ~ Feed across regulator
4 = Boll screw stud, upper
5 = Hinge stud
6 = Ball joint connection
7 = Boll stud, lower
8 = Feed across shaft
9 = Feed across shaft crank,
rear
Fig. 7 Feed across motion (cross section)
The groove on the inside face of the feed cam controls the feed motion
lengthwise of the machine bed. A roller which rides in this groove imparts
a reciprocating motion to the fwo-ormed feed regulator (Figs. 8& 9). The feed
regulator has a slot milled into its back side which accommodates the feed
regulator post. Both the feed regulator and the feed regulator post are
connected by o swivel (Fig. 8) which is held in place by a clamp and a
regulating screw. The more this swivel is moved downward, the larger will be
the effective arm of the feed regulator. And, conversely, the more the swivel
is moved upward, the smaller will be its effective orm. This device makes it
possible to adjust the amount of lengthwise travel of the feed plate carrier
bor.
Since both the work clomp and the feed plate are mounted on the feed
plate carrier bor and the workpiece is held in place between these parts, it is
moved positively from one stitch position to the next.
16
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1 = Feed plate
2 = Feed
across
driving
block
3 = Slide
block
4 = Feed plate carrier
bar
5 = Feed regulator post
6 = Work
clamp
7 = Feed regulator
swivel
8 = Swivel clamp
9 = Feed cam
10 = Worm wtieel
11 = Worm wheel
12 = Driving pulley
13
14
15
16
Idler pulley
Feed cam driving
worm
Arm shaft
Feed regulotor
Fig. 8 Feed lengthwise motion (longitudinal section)
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1 — Feed cam
2 = Roller stud
3 = Roller
4 = Feed regulotor
5 = Bearing bracket
6 = Slide block
7 = Guide plate
8 ~ Feed plate
9 = Swivel clamp
10 = Thumb screw
11 = Feed regulator swivel
12 = Feed regulator post
13 = Worm wheel shaft
14 = Worm wheel
15 = Feed cam driving worm
16 = Arm shaft
Fig.9 Feed lengthwise motion (cross section)
The adjustment possibilities inherent in the feed regulator and feed across
regulator ore not sufficient to produce larger tacks. Such tacks, however,
can be made with the aid of special organizational parts which provide for
alarger amount of work clomp travel lengthwise and ocross the machine bed.
c. Automatic Stop Motion
The machine is stopped automatically in order to ensure that all tacks will
be sewn with exatly the some number of stitches and that the machine will
always be in the same position when a new needle cycle begins. The shape
of the pattern-forming groove and the gear ratio of the worm gear ossem-
bly are determined by the number of stitches per tack.
The automatic stop motion is operated by the stop tripping segment on the
rim of the feed cam
(Fig. 10). When this tripping segment depresses the trip
ping lever, the latch at the lower end of the stop motion lever slips out of the
catch on the tripping lever so that the stop
motion lever can be pulled against
the stop com by a tension spring. Shortly before the stop com has completed
its last revolution, the stop link hits its surface and snaps into its groove, there
by causing the machine to stop. To absorb the momentum of the machine at
thissudden stop, the Pfaff 3334 isequipped with double buffersprings.
18
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