UnionSpecial 63900 Series Guide

ADJUSTING INSTRUCTIONS / ILLUSTRATED PARTS LIST
MANUAL NO. PT9636
STYLES
63900STREAMLINED
HIGHSPEEDNEEDLEFEED
TOPAND BOTTOMROLLERFEED
LOCKSTITCHMACHINES
63900AM
63900AML
63900AT
63900AW
63900AAE
REV.08/31/98

CONTENTS
•PREFACE............................................................................................................................................................... 4
•SAFETYRULES ........................................................................................................................................................ 5
•IDENTIFICATIONOFMACHINES........................................................................................................................... 6
•CLASS DESCRIPTION ........................................................................................................................................... 6
•STYLEOFMACHINES ............................................................................................................................................ 6
•ILLUSTRATIONS ...................................................................................................................................................... 6
•ILLUSTRATIONS(CONT.) ....................................................................................................................................... 7
•IDENTIFYINGPARTS .............................................................................................................................................. 7
•NEEDLES ................................................................................................................................................................ 7
•TABLEBOARD........................................................................................................................................................ 8
•BOBBINWINDER................................................................................................................................................... 8
•BELTS ..................................................................................................................................................................... 8
•LUBRICATION........................................................................................................................................................ 9
•RECOMMENDED OIL ........................................................................................................................................... 9
•OIL GAUGE .......................................................................................................................................................... 9
•SELF-PRIMINGHEADOILSIPHON ...................................................................................................................... 10
•INSTALLINGANDMAINTENANCEOFOILSIPHON............................................................................................ 10
•THREAD............................................................................................................................................................... 11
•REMOVINGTHEBOBBINCASE .......................................................................................................................... 11
•WINDINGTHEBOBBIN ....................................................................................................................................... 11
•THREADINGTHEBOBBINCASE.......................................................................................................................... 11
•THREADINGTHEBOBBINCASE(CONT.) ........................................................................................................... 12
•REPLACINGTHEBOBBINCASE.......................................................................................................................... 12
•INSERTINGTHENEEDLE ...................................................................................................................................... 12
•THREADINGTHENEEDLE .................................................................................................................................... 12
•PREPARATIONFORSEWING .............................................................................................................................. 12
•TENSIONS ............................................................................................................................................................ 12
•BOBBINTHREADTENSION .................................................................................................................................. 12
•BOBBINTHREADTENSION(CONT.) ................................................................................................................... 13
•NEEDLETHREADTENSION .................................................................................................................................. 13
•CHANGINGTHESTITCHLENGTH ....................................................................................................................... 13
•TIMINGTHENEEDLEFEEDWITHTHECONTINUOUSTURNINGROLLERFEED.................................................... 14
•PRESSUREONMATERIAL .................................................................................................................................... 14
•SETTINGTHENEEDLEBARTOHEIGHT ................................................................................................................ 14

CONTENTS(CONT.)
•TIMINGTHEHOOK ............................................................................................................................................. 15
•NEEDLEGUARDINSTRUCTIONS ......................................................................................................................... 15
•NEEDLEGUARDINSTRUCTIONS(CONT.) .......................................................................................................... 16
•HOOKLUBRICATION.......................................................................................................................................... 16
•PRESSERBARGUIDE ........................................................................................................................................... 16
•PRESERBARCONNECTION ............................................................................................................................... 16
•TENSIONASSEMBLYADJUSTMENT ..................................................................................................................... 17
•TENSIONRELEASE ............................................................................................................................................... 17
•THREADCONTROL............................................................................................................................................. 17
•THREADCONTROL(CONT.) .............................................................................................................................. 18
•BOTTOM COVER ................................................................................................................................................ 18
•HOOKSHAFT ...................................................................................................................................................... 18
•HOOK SHAFT (CONT.)........................................................................................................................................ 19
•REMOVAL OF OILING DEVICE .......................................................................................................................... 19
•REASSEMBLYOFOILINGDEVICE ...................................................................................................................... 20
•REASSEMBLYOFOILINGDEVICE(CONT.)........................................................................................................ 21
•UPPERMAINSHAFT ............................................................................................................................................ 21
•UPPERMAINSHAFT(CONT.) ............................................................................................................................. 22
•HANDWHEEL ...................................................................................................................................................... 22
•HANDWHEEL (CONT.)........................................................................................................................................ 23
•ATTACHMENTS ................................................................................................................................................... 23
•NEEDLEHOLEINSERT .......................................................................................................................................... 23
•MAINFRAME,BUSHING,OILGAUGEHEADOILSIPHONANDMISCELLANEOUSOILINGPARTS.................... 25
•MAINFRAME,BUSHING,OILGAUGEHEADOILSIPHONANDMISCELLANEOUSOILINGPARTS(CONT.) ..... 27
•MAINFRAMEMISCELLANEOUSCOVERSANDNEEDLETENSIONPARTS ......................................................... 29
•MAINFRAMEMISCELLANEOUSCOVERSANDNEEDLETENSIONPARTS(CONT.) .......................................... 31
•MAINANDHOOKDRIVESHAFTS,NEEDLEBARANDFOOTLIFTERMECHANISM............................................ 33
•NEEDLEFEEDDRIVINGPARTS............................................................................................................................ 35
•PRESSERFEET,PRESSERBAR,TOPFEEDROLLERMECHANISMANDATTACHMENTS ....................................... 37
•PRESSERFEET,PRESSERBAR,TOPFEEDROLLERMECHANISMANDATTACHMENTS ....................................... 39
•ROTATINGHOOKASSEMBLYANDHOOKOILINGPARTS ................................................................................ 41
•FEEDROLLERDRIVINGPARTS............................................................................................................................ 43
•FEEDROLLERDRIVINGPARTS(CONT.) ............................................................................................................. 45
•BOBBINWINDERANDMISCELLANEOUSACCESSORIES .................................................................................. 47
•NUMERICALINDEXOFPARTS ............................................................................................................................ 48
•NUMERICALINDEXOFPARTS ............................................................................................................................ 49
•NOTES ................................................................................................................................................................. 50
•NOTES ................................................................................................................................................................. 51

4
First Edition Copyright 1997
By
Union Special Corporation Rights Reserved In All Countries
Printed in U.S.A. October 1997
Manual No. PT9636 Illustrated Parts List for 63900 Series Machines
PREFACE
This parts manual has been prepared to assist you in locating individual parts or assemblies on 63900 Series
machines.
It is the desire of Union Special that each machine run at its optimum performance. Parts listed in this manual
are designed specifically for your machine and are manufactured with utmost precision to assure long
lasting service.
This manual has been comprised on the basis of available information. Changes in design and/or
improvements may incorporate a slight modification of configuration in illustrations or part numbers.
On the following pages are illustrations and terminology used in describing the parts used on 63900 Series
machines.

5
SAFETYRULES
1. Before putting the machines described in this manual into service, carefully read the instructions. The
starting of each machine is only permitted after taking notice of the instructions and by qualified
operators.
IMPORTANT! Before putting the machine into service, also read the safety rules and instructions from the
motor supplier.
2. Observe the national safety rules valid for your country.
3. The sewing machines described in this instruction manual are prohibited from being put into service until
it has been ascertained that the sewing units which these sewing machines will be built into, have
conformed with the EC Council Directives (89/392/EEC, Annex II B).
Each machine is only allowed to be used as foreseen. The foreseen use of the particular machine is
described in paragraph “STYLES OF MACHINES” of this instruction manual. Another use, going beyond
the description, is not as foreseen.
4. All safety devices must be in position when the machine is ready for work or in operation. Operation of
the machine without the appertaining safety devices is prohibited.
5. Wear safety glasses.
6. In case of machine conversions and changes all valid safety rules must be considered. Conversions and
changes are made at your own risk.
7. The warning hints in the instructions are marked with one of these two symbols:
8. When doing the following the machine has to be disconnected from the power supply by turning off the
main switch or by pulling out the main plug:
8.1 When threading needle(s), looper, spreader etc.
8.2 When replacing any parts such as needle(s), presser foot, throat plate, looper, spreader, feed
dog, needle guard, folder, fabric guide etc.
8.3 When leaving the workplace and when the workplace is unattended.
8.4 When doing maintenance work.
8.5 When using clutch motors without actuation lock, wait until the motor is stopped totally.
9. Maintenance, repair and conversion work (see item 8) must be done only by trained technicians or
special skilled personnel under consideration of the instructions.
10. Any work on the electrical equipment must be done by an electrician or under direction and supervision
of special skilled personnel.
11. Work on parts and equipment under electrical power is not permitted. Permissible exceptions are
described in the applicable sections of standard sheet DIN VDE 0105.
12. Before doing maintenance and repair work on the pneumatic equipment, the machine has to be
disconnected from the compressed air supply. In case of existing residual air pressure, after disconnect-
ing from compressed air supply (i.e. pneumatic equipment with air tank), the pressure has to be
removed by bleeding.

IDENTIFICATIONOFMACHINES
Each UNION SPECIAL machine is identified by a style number, which is stamped into the style plate affixed
to the middle of the machine under the tension assembly. The serial number is stamped into the serial
number plate affixed to the right rear base of the machine.
CLASS DESCRIPTION
High speed streamlined long arm needle feed lockstitch machines. one needle, light, medium and heavy
duty, continuous running roller feed, rotary hook, horizontal hook shaft, gears for changing stitch length, slot
segment for adjusting needle feed, 1 1/4 inch needle bar travel, one reservoir enclosed automatic
lubrication system, head oil siphon, adjustable hook oil control, needle bearing for take-up lever and needle
bar driving link, needle feed timing on upper shaft, maximum work space to right of needle bar 8 inches.
STYLEOFMACHINES
63900AM For making 3/8 on 1/2 inch turned down hem on legs of overalls, coveralls, and dungarees.
Seam Specification 301-EFb-1 inverted, Specify size of hem. Maximum recommended speed
5200 R.P.M.
63900AML Same as 63900AM except includes a hook with 52% greater bobbin capacity to reduce
frequency of bobbin changes.
63900AT For making a 1/2 or 2 1/2 inch hem turned by hand on children's wear, men's dress pants,
semi-dress pants and work pants. Sewn when garment reaches machine inside out. Seam
Specification 301EFb-1 or EFa-1. Maximum recommended speed 5200 R.P.M.
63900AW For top stitching waistbands on twill and woolen pants. Machine equipped to sew over belt
loops. Fitted with cloth plate extension. Seam Specification 301-SSa-1. Maximum recom-
mended speed 5200 R.P.M.
63900AAE Same as Style 63900AW, except fitted with spring guide keel on presser foot in line with
centerline of needle hole.
ILLUSTRATIONS
This manual has been arranged to simplify ordering repair parts. Exploded views of various sections of the
mechanism are shown so that the parts may be seen in their actual position in the machine. On the page
opposite the illustration will be found a listing of the parts with their part numbers, description and the
number of pieces required in the particular view being shown.
Numbers in the first column are reference numbers only, and merely indicate the position of the part in the
illustration. The reference number should never be used in ordering parts. Always use the part number listed
in the second column.
Component parts of sub-assemblies which can be furnished for repairs are indicated by indenting their
descriptions under the description of the main sub-assembly. As an example refer to the following text.
18. 29126EL Needle Feed Driving Eccentric and Connecting Rod Assembly ................................. 1
19. 22894J Set Screw .................................................................................................................. 2
6

7
ILLUSTRATIONS(CONT.)
When a part is common to all machines covered in this manual, no specific usage will be mentioned in the
description. However, when the parts for the various machines are not the same, the specific usage will be
mentioned in the description and, if necessary, the difference will be shown in the illustration.
*Ref. No. showing no Part No. is for location only. Part is not for sale separately.
A numerical index of all the parts shown in this manual is located at the back. This will facilitate locating the
illustration and description when only a part number is known.
IDENTIFYINGPARTS
Where construction permits, each part is stamped with its part number. On some of the smaller parts and on
those where construction does not permit, an identification letter is stamped in to distinguish the part from
similar ones.
PLEASE NOTE: Part numbers represent the same part, regardless of which manual they appear. On all
orders please include part number, name and style of machine for which the part was ordered.
For optimum performance use only genuine Union Special replacement parts.
NEEDLES
Each needle has both a type and size number. The type number denotes the kind of shank, point, length,
groove, finish and other details. The size number, stamped on the needle shank, denotes the largest
diameter of the blade measured between the shank and the eye. Collectively, the type number and size
number represent the complete symbol which is given on the label of all needles packed and sold by Union
Special.
TYPE DESCRIPTION
180GYS Round shank, round point, lockstitch, short length ball eye single groove, struck groove, deep
spot, chromium plated - sizes 075/029, 080/032, 090/036, 100/040, 125/049, 140, 054, 150/060.
180 GWS Round shank, round point, lockstitch, short length, oversize ball eye, single groove, struck
groove, deep spot, chromium plated - sizes 090/036, 100/040, 110/044, 125/049, 140/054.
When changing the needle, make sure it is fully inserted in the needle holder before the screw is tightened.
When ordering needles, please use the complete type and size numbers as printed on the package to
ensure prompt and accurate processing of your order. A complete order should read as follows: "100
needles, type 130 GS, size 125/049".

8
TABLEBOARD
The tableboard can now be mounted on the pedestal using four screws, adjusting the nuts so the top of the
tableboard is flush with the top of the machine bed plate.
BOBBINWINDER
The bobbin winder should be secured to the table top so that its pulley will be located directly in front of the
sewing machine belt and will bear against the belt when in operation. The base of the winder has two
elongated attaching holes, which allow the mechanism to be moved closer to or farther away from the belt
as needed. The pulley of the winder, when in operation, should exert only enough pressure against the belt
to wind the bobbin. Regulation and operation of the bobbin winder is described under "Winding The
Bobbin", under "Instructions For Operator's".
BELTS
These machines are equipped to use either #1 "Vee" or round belts.
Fig. 3

9
LUBRICATION
CAUTION! Oil has been drained from the main reservoir before shipment and the reservoir must be filled
before starting to operate.
Lubricate machine thoroughly, in accordance with instructions which follow, and run slowly for several
minutes to distribute the oil to the various parts. Full speed operation can then be expected without
damage.
RECOMMENDEDOIL
Use a stainless water-white straight mineral oil of a Saybolt viscosity of 90 to 125 seconds at 100° Fahrenheit
in the main reservoir. This is equivalent to Union special specification No. 175. Fill main reservoir at plug
screw (B, Fig. 3) and check oil level at gauge (C): oil is at maximum level when needle is in yellow band
marked "FULL". Oil should be added when needle is in yellow band marked "LOW".
It is recommended that a new machine, or one that has been out of service for an extended period, be
lubricated as follows: Remove the head cover and directly oil the bearings of the needle bar link, the take-
up and its lever and needle bar. Replace end cover, as no further hand oiling will be required.
Oil may be drained from main reservoir by removing plug screw (D, Fig. 3).
OIL GAUGE
The oil gauge is set at the factory to show the proper oil level in the reservoir. Should and adjustment
become necessary, the following steps should be followed:
1. Place the machine upright on a level table or bench.
2. Remove the reservoir plug screw (located below the handwheel and near the bottom of the
machine).
3. Oil should be added or removed so that the oil level is approximately 1/8 inch below the bottom edge
of the hole.
4. Loosen lock nut (E, Fig. 3) on the calibrating screw (F), and turn screw left or right so the gauge needle
rests on the yellow band marked "FULL" on gauge (C).
5. Tighten lock nut and replace plug screw.

10
10
SELF-PRIMINGHEADOILSIPHON
Class 63900 machines are equipped with a self-priming head oil siphon. When the machine is started, oil
splashes on the priming cup felt, filters through the felt and trickles down the vertical oil tube, thus priming
the siphon. Once the prime is established, it is maintained, unless the felt is removed. The siphon operates
twenty-four hours a day, removing oil at the rate of six to twelve drops per minute, which, of course, far
exceeds the rate at which oil collects in the head.
INSTALLINGANDMAINTENANCEOFOILSIPHON
A newly installed siphon starts its action within three to five minutes after the machine is operating. However,
it may be twenty minutes or so before all the air is removed from the line and the siphon is in full operation.
Within an hour, there should be a distinct reduction of the oil in the head sump. If the siphon does not
function, determine if the siphon intake tube, located in the head, is inserted in the felt block and that the
plastic tube is connected at both ends. If the above two items do not correct the siphon, replace the siphon
felts as described below.
The felt in the priming cup is designed for a specific purpose. This felt, No. 666-237, is to meter the flow of
priming oil and to prevent the entrance of air. The felt also acts as a filter and keeps the siphon clear of lint.
If the priming cup felt and the intake felt (666-214) becomes contaminated with an excessive amount of lint,
it may be necessary to replace the felts. The priming cup felt is replaced by removing access plug at back
of machine and replacing felt 666-237. For the best initial self-priming condition, the felt of the siphon should
be installed dry. The intake felt is replaced by removing the end cover.
However, if for some reason the priming cup felt has been oiled before installing, the siphon may fail
because air is trapped in the felt. As a precaution, remove felt from cup. Then, while squeezing the felt
between the fingers, saturate it well with oil. In other words, squeeze out the air and replace it with oil. This
prevents the trapping of air, and no trouble should be experienced when starting the siphon.

11
THREAD
While the direction of the twist in the bobbin thread is immaterial, the direction of the hook rotation favors
the use of a left twist thread in the needle. To determine the direction of twist, grasp a short length of thread
between thumb and forefinger of each hand. Turn the thread away from you with your right hand. If the
strands unwind, it is a left twist, if not, it is a right twist.
REMOVINGTHEBOBBINCASE
To remove the bobbin case, turn handwheel in operating direction until
needle reaches its highest position. Using the left hand, reach in under the
throat plate at left end of machine, open the bobbin case latch (A, Fig. 5),
and pull the bobbin case out of the sewing hook.
Opening the latch retains the bobbin in the case. When the latch is closed,
the bobbin is released and can readily be removed.
WINDINGTHEBOBBIN
Thread the bobbin winder by leading the thread from the supply down
through the eyelet (A, Fig. 6), down between the tension discs, and
under the tension post. Press an empty bobbin on the winder shaft (B),
up to the stop, wind the end of thread around the bobbin a few turns
in a clockwise direction and press downwardly on hand lever (D) until
pulley is moved into contact with machine belt, and is locked in that
position. When the machine is operated, the bobbin will be rotated
and filled until the thread engages the automatic throw-out member,
which disengages the pulley. The extent to which the bobbin is filled
can be varied by regulating the screw (C).
The tension post bracket is mounted on the winder base, and can be
shifted from left to right by loosening screw (E) so that any tendancy
of the bobbin to wind unevenly may be readily corrected.
The purpose of the bobbin winder is to assure an operator of a full
bobbin at all times. When the bobbin in the machine is used up,
replace it with the full one, and begin to wind the empty on immedi-
ately. Bobbins can be rewound while the machine is sewing.
THREADINGTHEBOBBINCASE
The bobbin case (A, Fig. 7) should be held between the thumb,
forefinger and second finger of the LEFT hand.
The bobbin (B) itself should be held between the thumb and forefinger
of the right hand with thread coming off the bottom of the bobbin.

12
THREADINGTHEBOBBINCASE(CONT.)
Place the bobbin in the bobbin case. In one continuous motion, with thumb and
forefinger of right hand, draw the bobbin thread through diagonal slot in bobbin
case (A, Fig. 8) under the tension spring (B) and into self threading slot (C) on case.
Mote direction of the rotation of the bobbin as the end of the thread is pulled when
looking at the bobbin case from the back. The bobbin should rotate counterclock-
wise.
REPLACINGTHEBOBBINCASE
Have the needle bar at tis highest position, allow about two and one half inches of
thread to hang free. The bobbin case latch should be opened with the left hand,
and by reaching under the throat plate and through the bed plate extension, it should be placed part way
into the sewing hook. the latch should then be released and bobbin case into position.
INSERTINGTHENEEDLE
Insert the needle into the needle bar as far as it will go, with the spot (sometimes called scarf)
towards the right, facing the handwheel. Tighten the nut securely.
The cross hole in the needle bar, about 1/4 inch from the end (A, Fig. 9), is to show the operator
when the needle has been inserted as far as it will go, and to provide a means for cleaning the
accumulated lint from needle hole so the needle will seat properly.
THREADINGTHENEEDLE
Threading diagram (Fig. 3) shows the places where the needle thread passes. Please note that
the needle thread passes through the needle eye from left to right.
PREPARATIONFORSEWING
With your left hand, hold the end of the needle thread, leaving it slack, and turn the handwheel in operating
direction until the needle moves down and up again to its highest position. Pull up the needle thread and
the bobbin thread will come up with it, through the needle hole in the throat plate. Draw both threads under
the presser foot.
TENSIONS
A perfect stitch is one in which the needle thread and bobbin thread are locked
together in the center of the material being sewn. A stitch of this kind is secured by
regulating the tensions on both threads.
BOBBINTHREADTENSION
The tension on the bobbin case is applied by means of a set screw (A, Fig. 10) which
regulates the tension spring (B). The tension on the spring is correct when it is just
sufficient to hold the bobbin case and bobbin suspended by the bobbin thread. The thread should not be
in the eyelet for this adjustment check.

13
BOBBINTHREADTENSION(CONT.)
Remove the bobbin case from its holder and turn set screw in spring
in a clockwise direction to apply more tension or counterclockwise
to release tension.
When the bobbin thread tension is correct, it rarely becomes nec-
essary to make any changes as varying the needle thread tension
will usually attain a good stitch.
NEEDLETHREADTENSION
The needle thread tension is varied by turning the tension regulating
nut (G, Fig. 3). Turning the nut in a clockwise direction increases the
tension, while counterclockwise decreases it. This should not be
done when the presser foot is in its raised position, but is generally
done while the machine is sewing on a piece of scrap material.
CHANGINGTHESTITCHLENGTH
Unless otherwise specified machine Styles 63900AM, AML and AT will
be equipped with upper feed regulator gear No. 63949-39 and
lower feed regulator gear No. 63949-41 to produce 9 stitches per
inch (S.P.I.), while Styles 63900AW, and AAE will be equipped with
upper feed regulator gear No. 63949-37 and lower feed regulator
gear No. 63949-43 to produce 10 S.P.I. Other gears are available and may be ordered separately. Refer
to "Gear Chart" below for the gears necessary to produce S.P.I. other than previously described.
GEARCHART
S.P.I. UPPERGEAR LOWERGEAR
6 63949-47 63949-33
7 63949-44 63949-36
8 63949-41 63949-39
9 63949-39 63949-41
10 63949-37 63949-43
11 63949-36 63949-44
12 63949-33 63949-47
To remove feed regulators gears, first remove feed drive gear cover located under arm of machine. Now
loosen screws (A and B Fig. 11) and slide gears (C and D) off their respective shafts. Replace with gears for
desired stitch length. After new gears have been installed be sure to reset needle feed stitch length to
agree with the continuous turning roller feed.

14
TIMINGTHENEEDLEFEEDWITHTHECONTINUOUSTURNINGROLLERFEED
Open top cover (A, Fig. 12) in the head of the machine and loosen needle
frame drive segment locking nut (B). Set connection stud (C) to point of
maximum number of stitches per inch of needle feed. This would locate the
connecting arm at letter "S".
Loosen two set screws on the needle frame drive eccentric (D). Rotate the
handwheel until the needle bar is at the bottom of its stroke. Rotate the
eccentric only, until the timing line (2) on the connecting arm and the
eccentric hub coincide. Tighten all screws, on every thick seams that
cause thread breakage advance needle feed timing slightly.
Rotate handwheel until the needle bar is at bottom of its stroke. The needle
bar should be vertical. If it is not, loosen clamp screw (F) and move needle
bar frame forward and backward until bar is vertical. Tighten screw,
making sure allside play is removed from between the needle bar frame
and the segment.
To set needle feed with roller feed loosen needle frame drive segment
locking nut. Set connection toward higher designated letter on segment
for approximate setting. Vary the needle travel so as to obtain the least
amount of needle deflection when the needle enters or leaves the thickest
section to be sewn.
PRESSUREONMATERIAL
The presser spring (A, Fig. 17) should exert only enough pressure on the feed
rollers to make the work feed uniformly. To increase the pressure on the
preser foot, turn presser spring regulator (B, Fig. 17) in a clockwise direction.
Turning the regulator counterclockwise decreases the pressure.
SETTINGTHENEEDLEBARTOHEIGHT
The three lines engraved on the needle bar are used in setting needle
bar to height, and are referred to as TIMING LINES.
Th middle and lower lines are used for Styles 63900M, T, and W. For
63900AM, AML, AAE, AT and AW the upper and middle lines are used.
When the needle bar is at its lowest position the upper timing line (B, Fig.
13) should be EVEN with the lower edge of the lower needle bar frame
(A).
To change the position of the needle bar, turn handwheel until the bar
is at its lowest position. Then, loosen the clamp screw (C) and move the
bar to the proper timing line. Keeping the needle bar line at its lowest
position, tighten the screw securely.

15
TIMINGTHEHOOK
Remove throat plate. Loosen three set screws (A) in the hook, and
hold the hook and the bobbin case holder in such a position as to
prevent interference with the needle. Turn handwheel in operating
direction until the needle bar is at its lowest position, and continue
to turn the handwheel until the needle is ascending and the middle
timing make (Fig. 13) used in setting the needle bar is even with the
lower edge of the needle bar frame (A).
Turn the hook on the shaft until the point of the hook is even with the
center of the needle and as close to the needle as possible without
deflecting it. A spacing of .003 to .005 inch between the needle and
the point of the hook is satisfactory. With the hook in this position,
tighten the set screw opposite the hook point securely. Then,
tighten the two remaining screws securely, and recheck the timing
of the hook with the needle. At the hook timing position the top of
the eye of the needle should be about 1/64 inch below the bottom
of the hook point.
Replace throat plate, allowing 1/32 inch clearance between the outside
edge of projection and the inside edge of bobbin case recess.
NEEDLEGUARDINSTRUCTIONS
In the hook, at the right side of the needle hole in bobbin case holder (B,
Fig. 15) is found a needle guarding surface (A, Fig. 15).
The purpose of this guarding surface is to prevent the hook point (C) from
coming in contact with needle (D) at loop-taking time, should the needle
be deflected toward the hook point. The needle guard will deflect the
needle slightly when needle is at bottom of its vertical travel if the hook is
properly timed. (At loop-taking time there should be little or no deflection
of needle by the needle guard.)
For additional needle clearance, especially with use of larger needles,
removal of some needle guarding surface may necessary.
Before metal removal from the guarding surface all related settings should be checked as follows:
1. See that the needle bar is set to correct height.
2. Check for proper hook timing.
3. Rotate the handwheel in operating direction by hand.
Check for excessive needle deflection beyond what is
cited on preceding page as a desirable condition.
4. If needle deflection is excessive, follow steps (A) and (B)
below.
(A) Remove bobbin case holder from hook.
(B) Remove excess metal from the needle guarding
surface. This may be done by using a diamond file
No. TT60 or fine emery cloth (#320), with one end secured to the bench, and rubbing the
guarding surface back and forth until sufficient metal is removed. When metal is being removed
from needle guarding surface, the bobbin case holder should be reinserted frequently and
tested until proper needle guarding is obtained.

16
NEEDLEGUARDINSTRUCTIONS(CONT.)
CAUTION! Damage to the hook point may result if too much metal is removed from the needle guarding
surface.
The bobbin case holder should be thoroughly cleaned before reassembly into the hook base.
When altering needle guarding surface, it is suggested that the hook NOT BE REMOVED or disturbed from its
timed position.
The bobbin case holder only may be removed by removing gib screws and gib and pulling on bobbin case
stem as the handwheel is rocked backward and forward slightly.
HOOKLUBRICATION
CAUTION! Do not run the machine without the bobbin case in the
hook as hook damage may result.
With the bobbin case in hook, run machine for a full minute. Place a piece
of white paper directly under the hook and continue running the machine.
After about five seconds, remove the paper and a definite and distinct
pattern of oil spots should be observed.
Should more or less oil be required, turn oil control adjusting shaft (H, Fig.
3), located on the front of the machine just blow the cloth plate surface,
in direction of the change required. After a change in the hook oil flow,
the machine should be run about one minute before checking for the
desired oil flow.
PRESSERBARGUIDE
When locating presser bar guide (C, Fig. 17) presser foot must rest directly
against throat plate. Proper setting of guide is 5 3/64 inches between
underside of presser bar guide and the top of throat plate (Fig. 17). To
obtain this setting, remove pressure from the presser spring (A) and loosen
set screw (D). Tap on presser foot to insure it is down against throat plate.
Set guide to the 5 3/64 inch dimension, center foot by turning it so needle
enters the middle of its slot and retighten screw (D). Apply pressure to top
feed roller by turning regulator (E) clockwise.
Set needle thread pull-up bracket (F) so that underside of wire is 4
5/8 inches above throat plate (Fig. 17).
PRESERBARCONNECTION
Presser bar conection (G, Fig. 17) should be set about 1/16 inch
below prese bar guide (C). Accomplish this by loosening lick nut (A,
Fig. 16), and relocating stop screw (B) on lifter lever bell crank (C),
located at the back of machine, under bed plate. turning stop
screw to right or left, properly sets presser car connection. Tighten
lock nut (A) to lock stop screw.

17
TENSIONASSEMBLYADJUSTMENT
Test check spring tension (A, Fig. 18). There should be enough tension to
assure a good returning snap when the spring is depressed and released.
Should it require adjusting, loosen set screw in head located under arm
and to the right of tension assembly and remove tension assembly.
Partially loosen tension post set screw (B) in tension post socket (C). Turn
tension post (D) counterclockwise until check spring moves away from
upper stop (E) and has no tension on it. Turn tension post (D) in a
clockwise direction until spring again touches upper stop (E). Proceed
further in same direction approximately 1/4 turn until desired tension is
obtained. When correctly set, tension post set screw (B) should be drawn
up snugly, yet not forcefully. Further adjustment of check spring tension
can be made by inserting a screwdriver into slotted end of tension post
(D) and turning in required direction.
Replace tension assembly with check spring about 3/8 inch above thread take-up bracket (A, Fig. 19).
Replace tension post assembly while presser foot is resting on throat plate.
TENSIONRELEASE
Tension release should be set so as not release when sewing over seams
or when presser foot is raised. Adjustment of tension release cam (H, Fig.
17) and in and out position of tension assembly are required for proper
operation.
The in and out position of the tension assembly is correct when the
tension discs are in line with the check spring eyelet (B, Fig. 19). Set the
stop screw (C, Fig. 19) so that when the flange of the tension assembly
rests against it, this position is maintained. Tighten the tension assembly
set screw.
The tension release cam (H, Fig. 17) should now be positioned by
loosening set screw (J) and then rising or lowering cam (H) to suit the
sewing conditions. The average release point is between 1/4 and 5/16
inch of presser foot lift above the throat plate. Tighten tension release cam set screw securely.
THREADCONTROL
Check the adjustment of tension assembly (A, Fig. 20) and
check spring tension. There should be enough tension to insure
a good returning snap when spring (B, Fig. 20) is depressed and
released. The check spring tension is adjusted from about 1 to
1 1/4 ounces when measured with a postal scale, No. 21227DN,
(C, Fig. 20). This is measured when the check is 1/32 to 1/16 inch
from the stop. The tension post set screw should be drawn up
snugly but not forcefully tightened (B, Fig. 18). The tension
release pin should move freely in the tension post (D, Fig. 18).
The check spring eyelet (B, Fig. 19), located just below the
tension discs, should be set for correct height as follows:
With a thread running from the tension post to the thread take-
up bracket (A, Fig. 19) in a straight line, the check spring eyelet
should be set 1/16 to 1/8 inch below the thread line (Fig. 19). Be
sure the eyelet is set close to the tension discs so that the check
spring will pass freely over it without obstruction. After making this setting, proceed to thread machine as
per threading diagram (Fig. 3).

18
THREADCONTROL(CONT.)
Sew slowly on a piece of material and observe the action of the check spring. The thread from the check
spring to the take-up bracket should be taut when the take-up is at the bottom if its stroke. Slight changes
in needle thread tension may necessary at this point, but a reasonable tension should be used to maintain
a uniform and consistent stitch. The machines are sewn off with 4 to 8 ounces maximum needle thread
tension on T120 or similar thread, using a postal scale (A, Fig. 21). Depress check spring when checking
tension. The check spring will feel heavy to you, but this is a required setting for Class 63900, and as a result,
the tension on the discs can be reduced.
BOTTOMCOVER
Before removing bottom cover, place machine on bench so that the plug screw is accessible from
underneath. Remove this plug screw and catch reservoir oil in some convenient container. Tip machine
back, loosen and remove the two cover screws. Cover should be tapped free with a wooden block or
mallet. Do not pry the cover loose with any sharp instrument as the gasket may become damaged.
CAUTION! When the bottom cover is removed, care should be taken not to mar or scratch the gasket
seat area of the machine bottom.
Before replacing cover, the machine gasket seat should be wiped clean and free of all lint and dirt. The
cover gasket should also be inspected for damage and cleaned of dirt. Two additional gaskets are used
to seal the bolts and must be cleaned before assembly. Carefully set the cover in place and tighten the two
bolts securely.
To replace a damaged cover gasket, proceed as follows:
1. Clean cover gasket recess of any foreign matter.
2. The gasket in cross section is triangular in shape with a groove in the top or widest part. With the cover
resting as it does in the machine, oil distributing plate to your right, begin inserting in the middle of the
back recess. The grooved wide edge of the gasket should be up and the ling sloped edge inward.
Continue pressing the gasket into the cover recess until gasket is in place.
The bolt sealing gaskets may have a tendency to fall out when the cover is being installed and may be
temporarily cemented in place by applying grease to their recesses. Torque to 72 inch lbs.
HOOKSHAFT
The hook shaft (A, Fig. 22) is held in
position by the pinion (B) and collar
(C) thrusting against hard steel wash-
ers (D) between the long left hand
bushing (E) and the short right hand
bushing (F).
Should hook shaft setting be dis-
turbed, the left and right position can
be determined by measuring from the
hook end of the hook shaft to the
point of a new needle (G) and read-
ing 9/16 inch on a scale.

19
HOOKSHAFT(CONT.)
To reposition the hook shaft, loosen the set screws of the pinion and collar and establish the 9/16 inch
dimension. Move the pinion and thrust washer against the left bushing, and after making certain one of the
set screws in on the shaft FLAT, tighten both screws securely. Liberally coat the collar and its washer with
oil and press the collar away from the pinion so as to remove all end play and tighten both set screws
securely.
Hook oiling is accomplished by a high speed rotary pump on the end of the hook shaft. The quantity of oil
supplied to the hook is regulated by the longer or shorter path the oil is required to travel through the
metering felt of metering cup (G, Fig. 23). (Increase or decrease of oil supply is controlled by a dial (P, Fig.
23) with an arrow marked "INCREASE", found below the cloth plate.) The hook oil feed roller (A, Fig. 23) which
rests against the metering cup felt serves not only to feed oil to the unit from the oil reservoir, but filters the
oil as well.
REMOVAL OF OILING DEVICE
The following steps are necessary to remove hook oiling device:
1. Remove hook oil feed roller (A, Fig. 23).
2. Remove hook oil control finger (B).
3. Apply finger pressure to hook oil control shaft (D) to prevent loss pump disc pivot pin (E); using Allen
wrench, loosen set screw (C). Move assembly slowly to right, being careful not to drop pivot pin
located on the end of the hook oil control shaft. When pivot pin is clear of pump disc (F), disc is free
to fall.
4. Remove metering cup (G) along with oil supply felt (K) and air seal felt (J).
5. Remove cop (H) from hook oil control shaft.

20
REASSEMBLYOFOILINGDEVICE
Before reassembly, the end of the hook shaft, its spiral groove and the pump disc should be thoroughly
cleaned. Remove any end play found in the hook shaft and determine that the 35/64 inch dimension has
been maintained (Fig. 22).
The following steps are necessary to reassemble the hook oiling device:
1. Remove and separate the air seal felt (J, fig. 23) from oil supply felt (K).
2. Make sure small end of air seal spring (R) is located on boss of metering cup behind felt attached to
cup. Position the metering cup (G) and air seal spring on the hook shaft (S) with open end toward
handwheel end of the machine (Fig. 23).
NOTE: The hook shaft should pass through hole of felt attached to metering cup.
3. Position oil supply felt (K, Fig. 23) on the hook shaft, making certain the felt's projection extends into
dovetail of metering cup.
4. Position air seal felt (J) on hook shaft.
5. Insert pump disc (F) into assembly tool No. 21227BY, with the stop pin on the spring side of tool, 180°
from handle. Insert disc approximately half way into the spring and center in tool (Fig. 25).
6. Insert hook oil control shaft (D, fig. 23) and its bushing (L) part way into its boss which is located directly
behind the hook shaft, being careful NOT TO DROP the pump disc pivot pin (E).