Pfaff 918 Adjustment Manual
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Pfaff 918 Adjustment Manual

Pfaff 918 Adjustment Manual

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918
938 U
ADJUSTMENT MANUAL
938
938 U
This Adjustment Manual is valid for machines
from the following serial numbers onwards:
# 2 671 899
296-12-18 998/002
Justieranleitung engl. 06.12

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Summary of Contents for Pfaff 918

  • Page 1 938 U ADJUSTMENT MANUAL 938 U This Adjustment Manual is valid for machines from the following serial numbers onwards: # 2 671 899 296-12-18 998/002 Justieranleitung engl. 06.12...
  • Page 2 The reprinting, copying or translation of PFAFF Service Manuals, whether in whole or in part, is only permitted with our previous authorization and with written reference to the source. PFAFF Industriesysteme und Maschinen AG Hans-Geiger-Str. 12 - IG Nord D-67661 Kaiserslautern...

  • Page 3: Table Of Contents

    .05.08 Zigzag stitch movement (only on the 918 and 938) ............. 14 .05.09 Needle penetration symmetry - left, centre and right (only on the 918 and 938) ....15 .05.10 Multi-stitch movement (only on the 918U and 938U) ............16 .05.11...
  • Page 4 Index Contents ..................Page Adjusting the underedge trimmer -771//05 ................. 40 .06.01 Resting position of the knife ....................40 .06.02 Knife height ......................... 41 .06.03 Positioning of the knife ......................42 .06.04 Knife drive switch ......................... 43 .06.05 Workpiece guard ........................44 Adjusting the thread trimmer -900/24 .................

  • Page 5: Adjustment

    Adjustment Adjustment On the PFAFF 918 and 938 do not use a screw clamp on the needle bar! The special coating of the needle bar could be damaged. Please observe all notes from Chapter 1 Safety of the instruction manual! In particular care must be taken to see that all protective devices are refi...

  • Page 6: Check And Adjustment Aid

    Adjustment Check and adjustment aid By blocking with holes 1 - 5 the required needle bar positions can be fi xed ex- actly. Fig. 1 - 01 ● Turn the balance wheel until the needle bar has approximately reached the required posi- tion.

  • Page 7: Adjusting The Basic Machine

    Adjustment Adjusting the basic machine Balancing weight .05.01 Requirement With the needle bar at bdc the largest eccentricity of the balancing weight 1 must be pointing upwards. Fig. 1 - 02 ● Bring the needle bar to b.d.c. ● Adjust the balance weight 1 (screw 2) in accordance with the requirement.

  • Page 8: Centering The Needle In The Needle Hole (In Sewing Direction)

    Adjustment Centering the needle in the needle hole .05.02 (in sewing direction) Requirement With the zigzag setting at "0" and the needle position set at "middle" the needle must enter the center of the needle hole as viewed in the direction of sewing. Fig.

  • Page 9: Parallel Guiding Of The Needle Bar

    Adjustment Parallel guiding of the needle bar .05.03 Requirement Guide bar 5 must be parallel to the needle bar. Fig. 1 - 04 ● Bring the needle bar to tdc (hole 2). ● Loosen screws 1,2 and nut 3. ● The largest eccentricity of pin 4 must be facing downwards. ●...

  • Page 10: Locking Lever

    Adjustment Locking lever .05.04 Requirement The zigzag stitch adjustment lever 3 must be able to be locked in any position. Fig. 1 - 05 ● Loosen screw 2. ● Press locking lever 1 against the zigzag stitch adjustment lever 3. ●...

  • Page 11: Zero Stitch And Zigzag Stitch Scale

    Adjustment Zero stitch and zigzag stitch scale .05.05 Requirement With the zigzag stitch set at "0": 1. the needle bar must not move laterally when the balancewheel is turned and 2. the marking "0" on scale 1 must be at marking 2. Fig.

  • Page 12: Centering The Needle In The Needle Hole (Crosswise To Sewing Direction)

    Adjustment Centering the needle in the needle hole .05.06 (crosswise to sewing direction) Requirement With the zigzag stitch set at "0" and the needle position setting at "middle" the needle must enter the center of the needle hole as seen across the direction of sewing. Fig.

  • Page 13: Zigzag Stitch Width

    Adjustment Zigzag stitch width .05.07 Requirement At the largest zigzag stitch setting, marking 1 must be at the largest zigzag value on scale 2. Fig. 1 - 8 ● Turn the zigzag stitch adjustment lever 3 in accordance with the requirement. ●...

  • Page 14: Zigzag Stitch Movement (Only On The 918 And 938)

    Adjustment Zigzag stitch movement .05.08 (only on the 918 and 938) Requirement When the needle bar, on the right of its throw, is positioned at t.d.c. (adjustment hole "2"), the needle bar should not move laterally when the zigzag stitch adjustment lever is mo- ved to and fro.

  • Page 15: Needle Penetration Symmetry - Left, Centre And Right (Only On The 918 And 938)

    Adjustment Needle penetration symmetry - left, centre and right .05.09 (only on the 918 and 938) Requirement When the zigzag stitch is set at "0", the needle should penetrate in the centre of the needle hole. With the maximum zigzag stitch set, the needle should penetrate on the left and right at the same distance from the centre hole.

  • Page 16: Multi-Stitch Movement (Only On The 918U And 938U)

    Adjustment Multi-stitch movement .05.10 (only on the 918U and 938U) Requirement 1. When the needle, at its b.d.c., penetrates on the right-hand side, the recess 5 on the control cam 3 should be positioned horizontally towards the rear. 2. The lateral movement of the needle bar should have been completed when the needle penetrates the workpiece (carry out a check with the largest zigzag setting).

  • Page 17: Zigzag Movement (Only On The 918U And 938U)

    Adjustment Zigzag movement .05.11 (only on the 918U and 938U) Requirement When the needle bar, moving from its right b.d.c., reaches its t.d.c. (hole 2), it should not carry out any lateral motion when the zigzag stitch width lever 4 is moved to and fro. Fig.

  • Page 18: Target Positioning Sensor (Only On The 918U And 938U)

    Adjustment Target positioning sensor .05.12 (only on the 918U and 938U) Requirement There should be a clearance of 0.2 – 0.3 mm between sensor 1 and control cam 3. Fig. 1 - 12 ● Adjust sensor 1 (screws 2) in accordance with the requirement.

  • Page 19: Needle Position Adjustment Lever

    Adjustment Needle position adjustment lever .05.13 Requirement The left and right throws of the needle must be the same size at the largest zigzag stitch setting and at the left or right needle position. Fig. 1 - 13 ● Loosen screws 1 and 2. ●...

  • Page 20: Zero Position Of The Bottom Feed Dog (With Closed Gear Box)

    Adjustment Zero position of the bottom feed dog .05.14 (with closed gear box) Requirement With the stitch length set at "0", the bottom feed dog should not carry out any feeding motion when the balance wheel is turned. Fig. 1 - 14 ●...

  • Page 21: Zeroing The Bottom Feed (With Open Gearbox)

    Adjustment Zeroing the bottom feed .05.15 (with open gearbox) Requirement With the stitch length set at "0" the bottom feed dog must not carry out any feeding moti- on when the balance wheel is turned. Fig. 1 - 15 ● Switch on the machine. ●...

  • Page 22: Feeding Motion Of The Bottom Feed Dog

    Adjustment Feeding motion of the bottom feed dog .05.16 Requirement With the maximum stitch length set and the needle bar position 1.0 past tdc (hole 4), the bottom feed dog must not move when the reverse feed lever is pressed. Fig.

  • Page 23: Lifting Motion Of The Bottom Feed Dog

    Adjustment Lifting motion of the bottom feed dog .05.17 Requirement With the stitch length set at "0" and the needle bar position at 0.25 mm past tdc (hole 3) the bottom feed dog must be at its upper point of reversal. Fig.

  • Page 24: Drive Belt In The Gearbox Housing

    Adjustment Drive belt in the gearbox housing .05.18 Requirement Drive belt 4 must be tightened so that the machine runs freely and the belt sprockets do not have any noticeable play. Fig. 1 - 18 ● Adjust eccentric bearing bush 1 (screw 2) in accordance with the requirement and so that drive belt 4 is in the centre of bobbin opener drive wheel 3.

  • Page 25: Hook Bearing Bracket

    Adjustment Hook bearing bracket .05.19 Requirement The hook shaft must be touching the hook bearing bracket adjustment gauge 1 at the top and the side. 438 - 439 Fig. 1 - 19 ● Loosen screw 3. ● Swing the bobbin case opener to the right and remove the hook. ●...

  • Page 26: Hook Lubrication

    Adjustment Hook lubrication .05.20 Requirement When the machine is running at full speed, after about 10 seconds a fi ne oil streak should be visible on a strip of paper held over the needle plate cutout. Fig. 1 - 20 ●...

  • Page 27: Pre-Adjusting The Needle Height

    Adjustment Pre-adjusting the needle height .05.21 Requirement With the needle bar at tdc (hole 2) the distance between the point of the needle and the needle plate must be 19 mm. 19 mm Fig. 1 - 21 ● Without turning it, adjust the needle bar (screws 1) in accordance with the requirement.

  • Page 28: Needle Rise, Hook-To-Needle Clearance And Bobbin Case Positioning-Fi Nger

    Adjustment Needle rise, hook-to-needle clearance and bobbin case positioning-fi nger .05.22 Requirement 1. With the needle position set at "middle", the zigzag stitch setting at "0" and the needle bar position 2.0 past bdc (hole 1) the hook point must be in the middle of the needle and the distance between the needle and the hook point must be 0.05 - 0.1 mm.

  • Page 29: Final Adjustment Of The Needle Height

    Adjustment Final adjustment of the needle height .05.23 Requirement With the zigzag stitch set at "0", the needle position set at "left" and the hook point in the middle of the needle, the top edge of the needle eye must be 0.5 mm underneath the hook point.

  • Page 30: Bobbin Case Opener Position

    Adjustment Bobbin case opener position .05.24 Requirement 1. There must be a clearance of 0.5 mm between the top edge of the bobbin case opener and the inner edge of the bottom section of the bobbin case. 2. Between the bobbin case opener fi nger and the bottom section of the bobbin case opener there must be a clearance of 0.8 mm.

  • Page 31: Bobbin Case Opener Motion

    Adjustment Bobbin case opener motion .05.25 Requirement With the needle bar 2.0 past bdc (hole 1) the bobbin case opener 3 must be at its right point of reversal. Fig. 1 - 25 ● Adjust bobbin opener eccentric 1 (screws 2) in accordance with the requirement.

  • Page 32: Bottom Feed Dog Height

    Adjustment Bottom feed dog height .05.26 Requirement With the stitch length set at "0" and the needle bar position at 0.25 past tdc (hole 3) the bottom feed dog must be in the middle of the needle plate cutout and be touching the feed dog height-adjustment gauge along its entire length.

  • Page 33: Presser Foot To Needle Plate Clearance

    Adjustment Presser foot to needle plate clearance .05.27 Requirement When the hand lever is raised, the needle should penetrate exactly in the "needle hole cen- tre" of the presser foot and the presser foot to needle plate clearance should be 7 mm. Fig.

  • Page 34: Presser Foot Pressure

    Adjustment Presser foot pressure .05.28 Requirement Even at top sewing speed the material should be fed without problems. There should be no pressure marks on the material. Fig. 1 - 28 ● Turn screw 1 in accordance with the requirement. The presser foot pressure (screw 1) can be increased ( ) or reduced ( ) as...

  • Page 35: Needle Thread Tension Release (On Machines Without -900/24)

    Adjustment Needle thread tension release .05.29 (on machines without -900/24) Requirement When the hand lever is raised, the tensions disks should be at least 0.5 mm apart. 0,5 mm Fig. 1 - 29 ● Loosen screw 1 and press linkage rod 2 down as far as possible. ●...

  • Page 36: Thread Diverter Pin

    Adjustment Thread diverter pin .05.30 Requirement With the needle bar at bdc the top edge of the thread guide hole must be at the same height as the bottom edge of the thread diverter. Fig. 1 - 30 ● Adjust thread guide bar 1 (screw 2) according to the requirement, taking care that it is parallel to the bed-plate.

  • Page 37: Limiting The Knee Lever Stroke

    Adjustment Limiting the knee lever stroke .05.31 Requirement When the knee lever is pressed the hand lever must drop automatically and the presser foot must be just over 7 mm above the needle plate. Fig. 1 - 31 ● Place the feed dog gauge under the presser foot with its recess facing downwards. ●...

  • Page 38: Knee Lever Play

    Adjustment Knee lever play .05.32 Requirement When lightly pressing the knee lever there should be a noticeable play between nut 1 and fork 3. Fig. 1 - 32 ● Adjust nut 1 (nut 2) in accordance with the requirement and lock it with nut 2.

  • Page 39: Bobbin Winder

    Adjustment Bobbin winder .05.33 Requirement 1. With the bobbin winder engaged the bobbin winder spindle must be turned reliably, but friction wheel 3 must not touch drive wheel 1 when the bobbin winder is switched off. 2. The bobbin winder must disengage automatically when the thread is approx. 1 mm from the edge of the bobbin.

  • Page 40: Adjusting The Underedge Trimmer -771//05

    Adjustment Adjusting the underedge trimmer -771//05 Resting position of the knife .06.01 Requirement When adjustment lever 1 is set at "0", the knife stroke should be as small as possible. 90° Fig. 1 - 34 ● Unscrew the milled screw of adjustment lever 1 (screw 2). ●...

  • Page 41: Knife Height

    Adjustment Knife height .06.02 Requirement When the adjustment lever 1 is set at "0" and the knife is at the top of its stroke, the top edges of the needle plate and knife should be at the same level. Fig. 1 - 34 ●...

  • Page 42: Positioning Of The Knife

    Adjustment Positioning of the knife .06.03 Requirement The knife should be touching the counter blade and be positioned at a slight slant to the sta- tionary knife. Fig. 1 - 35 ● Adjust eccentric 1 (screw 2) in accordance with the requirement.

  • Page 43: Knife Drive Switch

    Adjustment Knife drive switch .06.04 Requirement When the adjustment lever 1 is set at "0", the knife drive unit must be switched off, and from position "1" on it must be switched on. Fig. 1 - 36 ● Set adjustment lever 1 at "0". ●...

  • Page 44: Workpiece Guard

    Adjustment Workpiece guard .06.04 Requirement Workpiece guard 1 should be as close as possible to the knife 3 and be touching stop 4. Fig. 1 - 37 ● Adjust workpiece guard 1 (screws 2) in accordance with the requirement.

  • Page 45: Adjusting The Thread Trimmer -900/24

    Adjustment Adjusting the thread trimmer -900/24 Axial position of the control cam .07 .01 Requirement 1. Roller 5 should be at a distance of 0.3 mm from the control cam 1. 2. Adjustment ring 3 should be touching the control cam 1. 0,3 mm Fig.

  • Page 46: Preliminary Adjustment Of The Control Cam

    Adjustment Preliminary adjustment of the control cam .07 .02 Requirement 1. In the needle rise position (hole 1) the roller lever 4 should lock into the corresponding groove of the control cam. 2. The control cam 1 should be touching adjustment ring 3. Fig.

  • Page 47: Position Of The Thread Catcher And Cutting Test

    Adjustment Position of the thread catcher and cutting test .07 .03 Requirement When the thread trimmer is in its neutral position, the edge of thread catcher 6 should be fl ush with the edge of the mounting plate 4. Fig. 1 - 40 ●...

  • Page 48: Readjustment Of The Control Cam

    Adjustment Readjustment of the control cam .07 .04 Requirement 1. When the end of the hook guard 3 is level with of the right edge of the bobbin case position fi nger 4, the thread catcher 5 should begin moving forwards. 2.

  • Page 49: Needle Thread Tension Release

    Adjustment Needle thread tension release .07 .05 Requirement 1. When solenoids 3 are activated, the tensions disks 4 should be at least 0.5 mm apart. 2. When the thread trimmer is in its neutral position and the sewing foot is positioned on the needle plate, the tension should be fully effective.

  • Page 50: Circuit Diagrams

    -771/05 M2 knife motor (optional) -900/.. thread trimmer (FS) -909/03 thread wiper -910/.. automatic presser foot lift X25.1 -911/.. backtacking device X25.2 -918/18 zig-zag switch Thread tension release (FSL) Keyboard Start inhibitor Sewing head identifi cation (OTE) -900/.. thread trimmer -909/03 thread wiper -910/..
  • Page 51 91-191 469-95 Circuit diagrams Part 1 Version 01.02.06...
  • Page 52 Circuit diagrams 91-191 469-95 Version 01.02.06 Part 2...
  • Page 53 91-191 469-95 Circuit diagrams Part 3 Version 01.02.06...
  • Page 54 PFAFF Industriesysteme und Maschinen AG Hans-Geiger-Str. 12 - IG Nord D-67661 Kaiserslautern Phone: +49 - 6301 3205 - 0 Fax: +49 - 6301 3205 1386 E-mail: info@pfaff-industrial.com Hotlines: Technical service: +49 - 175/2243-101 Application consultance: +49 - 175/2243-102 Spare-parts hotline:...

This manual is also suitable for:

938 u938

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